+C : The Variable Constant

Alternative Solutions for Things That Don't Fit

2012-01-29T17:57:00.001-05:00

For people who find incompatibilities between some new object and the space the old one sat, there are really three options:

Get a new environment
Don't use the new object
Rebuild ALL THE THINGS

I have a SFF case for my Lenovo M90 Desktop and wanted to increase my gaming/rendering performance by purchasing an new GPU. I settled on this nice Asus board, which had a ATI HD mobility Radeon 6570 attached to it, but when it came I quickly realized that it didn't fit in my case.

The top board is the new one and the bottom board is a NVIDIA GeForce 310. There was at least some .25" to .375" height difference due to the heatsink and as a result it touched the hard disk mounting bracket.

Yeah that's not much space...

Everyone seemed to suggest to buy a new case (choice #1). Myself, being a maker and machinist at heart, decided on choice #3.

Tada! It was easier to move the hard drive than move the PCI-E slot, so I redesigned the mounting case and shifted its location a fractional amount away from the graphics unit. Because we have 3D printers in the studio, I decided it was time to massively abuse them.

6 hours later...

Made off the Invention Studio's uPrint.

Old and the New

Part of the adaptation included slicing the wings off this cast aluminum piece. At this point, im pretty sure the warranty is void.

The new mount uses 6-32 screws to attach to the hard drive, and some small perforations to clip onto the inside of the case.

To keep things from bouncing around, I threw in stacks of leftover rubber grommets I bought for the Hardboard Project. Glad I could find a use for them.

So there it sits complete! Now I know what many of you are thinking. You are using melted plastic to hold a part nearby a notoriously hot object. Won't it melt? The answer is hopefully not. ABS melts at somewhere around 225 deg F, which converts to 107.2 deg C. The heatsink is not actually touching the ABS, and the convection currents internal to the PC should work in my favor, decreasing the edge temperature of the heatsink alloy and cooling the ABS. Besides, should my GPU get over 100 deg C I think I have larger problems to worry about.

And oh hey! 3D printed Soap!

Wheelpod: Chain Conversion

2012-01-23T01:16:00.000-05:00

I found out about two weeks after I placed my order that McMaster's custom chain length item is meant for link numbers divisible by two. Awww shucks, I couldnt trick the system. I calculated previously a length of 51 links for a perfect chain length so they called me up one morning and handed me the unfortunate news. I would have been bummed, except I had already gotten tired of waiting and decided to beat it anyway with some surplus chain given to me by Aaron Fan.

The sprocket was the tricky part. Because I'm cheap, I neglected to buy any appropriately thick metal to cut #25 sprockets out on the waterjet. So I ended up with a 3/16" thick plate of mystery steel from the scrap pile. Most sprockets of #25 are some 3/32" thick with an edge taper. This piece of metal would require a good amount of working with some care for symmetry. My first thoughts were to add the bevels on the lathe, but we didnt have tooling shallow enough not did I want to disrupt the squareness of the toolpost. This is what I ended up doing.

Ah yes, I feel like a high school student again. That is a right-angle drill chucking a cap screw, which is holding a plate of aluminum that has the sprocket bolted to it. The assembly spins against a belt sander and adds a bevel (slowly).

Another shot.

Surprisingly enough, the technique worked well.

Now excuse me as I tempt fate with my 30mph nonsense on wheels.

I Accidentally...

2011-12-29T19:53:00.001-05:00

...my last urethane belt. Look at that snaggletooth.

As I began reassembling Razor Wind after cleaning it up, I neglected to check the motor direction before stepping outside for a test run. After the initial kick start, I threw the throttle only for it to instantaneously brake and change directions. Stripped all the teeth off.

Time to order the upgrades.

Also, I finally got the institute's mascot on my scooter. Been wanting this shot for years.

Razor Wind: Shredding is a Pro for Guitarists, but not for Power Transmission

2011-12-25T03:24:00.000-05:00

I've been running the Wheelpod system for about 3-4 weeks now and needless to say it has been an interesting experiment with pulley diameters and belt materials. I began with a 13T motor pulley, a 29T wheel pulley, and a 3/8" wide XL neoprene/fiberglass timing pulley. After a few runs, I noticed the drive producing extra grinding sounds and added a tensioner to absorb the thermally induced slack. Days later, the belt actually snapped.

All the teeth seemed to have rounded a bit (nominal trapezoidal shape) but the failure point was clear. The tension members all failed at one point, where the belt broke. At least I was in front of my apartment when it happened. Had I been at the Invention Studio, I might have been raging a bit.

So what happened? Easiest assumption is the wrong material. My second choice was a urethane belt, with kevlar tension member. Kevlar? HELLS YES! I also knew from experience that the urethane timing belts suffered less form expansion. I was hoping this combination alone would be able to solve my problems.

I did however have to change the motor pulley, because the Urethane belts came in intervals of 5 teeth (5 x .2" = 1" differences between belts) which meant I had to recalculate my belt distances. A new pulley with 11T was swapped for the 13T.

Can anyone guess what is going to happen next?

Well I blatantly ignored the minimum tooth requirement for most timing pulleys. Basically the number of teeth in contact with the motor pulley were not enough to resist the force required to move a human body at that ratio. Most (if not all the teeth) eventually sheered off like in the belt below.

And this belt too...

And this belt most recently. Luckily I had purchased enough belts to make it past my finals week (otherwise I would have surely been late to each one). The problem was clearly not belt or tension cord material. After consulting the problem from a few different angles I determined to cause to be the pulley diameter.

Increasing the pulley diameters (proportionally) would not change my overall ratio, but would allow a greater number of teeth in contact. This redistributes the sheer forces acting on each contact belt tooth.

While I was at it, I figured I would redesign the wheelpod chassis for 'real' belt lengths, and a dynamic belt tensioner.

However in the interest of saving time and material, I've elected to skip the experimental belt steps and revert to a method that has worked before: #25 chain. I will still be increasing the sprocket diameters to distribute the loads, but I will be using metal roller chain, which supports much higher working loads.

Starting with the largest motor side sprocket I could support and the center to center distance between the motor and wheel, I used this nifty chain length calculator to empirically determine a combination of chain and ratio that would suffice. The only limitations is that the sprocket tooth number and the # of chain links had to be integer values. In the end, I chose a 14T motor sprocket, 31T wheel sprocket, and a chain of 51 links. That gives an overall ratio higher than the current setup, but hell I know the motor can output enough power to make the scooter fly.

Machining to take place the moment I return to Tech. But until then, Happy Holidays!

Razor Wind: Motorpod Edition

2011-12-18T02:19:00.000-05:00

Shortly after the demonstration video shoot for the Clough Undergraduate Learning Commons, I burned out the version 1 wheelmotor. I knew the motor was running hot, I thought I had seen some sparks fly out the side, but I wasnt alarmed. Not until smoke billowed from the nearly air-tight electronics compartment was I actually worried.

Turns out some screws loosened, some wires shorted, and magnet wire combusted. Some serious weld marks were left inside my frame.

So I disassembled it and left it aside. I got pretty tired of fiddling with wheelmotors after rebuilding neumotor 2-3 times so I designed an alternate power system: The Wheelpod.

Behold!

A separate power drive system that easily slips into the space of the old one. This particular design slipped in between the two main frame rails and bolted/pivoted about the old wheel axle location. Mechanical tabs prevent the module from rotating in any undesirable direction. When a person stood on the scooter, the rotation about the pivot point applied a counter rotational force on the rear footrest spoiler and the from plate about the speed controller cover.

But what for drive? I spent a fair amount of time perusing the new line of Hobbything Turnigy SK3 motors when I realized Xo and I had one remaining unmodified Turnigy 6364-280 from Hardboard.

I never thought I would be reassembling one of those motors.

Some quick calculations: 280kv @ 22.2V, with 4" wheels and a ~2.2:1 belt ratio leaves about 30 MILES PER HOUR. YESSSSSSSSS!

The device went together about as quick as the waterjet could sneeze its watery sand snot.

Waterjet timing pulley using the low-taper cut settings to prevent belt deviations due to taper. The bore was turned to accept a giant-ass ball bearing. Eight holes run through the entire assembly to secure all parts.

Wheels were also bored out. The preferred Colson 4" x 1.25" was selected because it offered the most thermoplastic core. The 1.5" and 2" wide versions has much more rubber and made turning difficult. For this design, I decided to enhance the rigidity of the wheel by adding aluminum plates to each side. This would give the bearings a better material to sit in and provide a more positive material to tap and thread.

The stack, not yet ready to be pressed in.

For some reason I managed to epically fail with hole placement. It did not occur to me the THRU diameter of #6 hardware, but I was left with this case regardless. So I did what any 'sensible' engineer would do and take a reamer to it. Don't hurt me too much.

The results were actually reasonable. It was very tight, but enough screws passed through to finish the piece. The way I see it, I have some potent 'thread locker' in this assembly.

The protruding screws were screwed into the timing pulley above. After turning some spacers, boring out timing pulleys, and screwing stuff:

One thing I neglected to do was design the sensor module. As a result, it is currently running sensorless. While it is less a headache for me, I would like to someday add a data collection module in the scooter so I can produce REAL values for comparison. Someday...

This is the Remix

2011-10-14T11:20:00.003-04:00

I actually began toying with this idea awhile back, but since Cake's drums have become worn I figured it was time to try it out.

The integrated brushless eggbeater.

I've generally kept away from it because the internals are essentially open and thus vulnerable to a direct hit. To ensure safety of my motor and electronics, the beater must spin fast and never stop. Those two terms became the primary focus points in a new revision of Cake, which I might end up giving a new name as there are enough changes to warrant a new design.

Besides, I could never supply a very good explanation of why it is named Cake. I guess that rules out Cupcake as a possible name.

I bought a new motor and battery from Hobbyking. A Turnigy 1450kv motor of the same stator size coupled with a 4-cell 1000mAh lipoly. This is a 350kv increase in motor, and 3.7v, 200mAh increase in battery spec. Expect longer runtimes and higher end rpms. No load (unrealistic) of ~21k rpms! Most other spinning weapons sit around 10k - 15k range, so I have no doubt I'll be spinning quicker than them. The exception of course are Gene and Richard's creations (~49k rpms?) so I'll have to design a strategy to fight those.

Here is the model. Already I am beginning to like this design because it addresses some of the complications I have found with the drum design. First, there are no endcaps. The beater is machined from a single piece of A2 tool steel, and thus has its endcaps permanently fixed to the knockers. Assembly of the motor will be more complex certainly, but I think the benefits outweigh the complications.

I hope to never need to machine another beater ever again. First, I rough cut the 1" block of steel on the waterjet leaving .01" on all edges. Then, I moved the block to the manual mill, squared all the edges,and removed the extra .01". Finally, I faced the beater. All operations probably totaled to 12 hours of work.

Worst yet, I managed to make 3 mistakes on the part. Good thing I am such a improvising badass. Can you spot the mistakes?

Rapid prototyping the magnet can mount. I blame Charles for this recent fascination in 3D printing. And before you ask, the answer is no. That part will not remain extruded ABS.

Speaking of rapid prototyping, what exactly are these?

These are the next set of bad ideas in this revision: Angled armor plates and isolated but integrated frame gearmotors. These ideas I've been designing since Attrition but never had the resources to implement it. Times ave changed. While the Dimension spat out the can mount, I had the uPrint mush out the angled mating blocks. The current plan is the remake them from aluminum but I have no patience and wanted to see it all together.

Bingo! Geometry test pass!

My next goals are to complete the drive system. Some minor complications for the moment: The battery supplied from Hobbyking is just a few unforeseen millimeters too wide. As a result, my Scorpion HX speed controller does not fit as intended. I may need to reinvest in single motor controllers and utilize the 45 degree drive method (Sans mixing). I've also noticed a large amount of frictional binding when the gearboxes are populated. Closer inspection showed the holes to be drilled at a slight angle. UGH! Should I continue with the B16 mod, I will have to bore out the holes to 9mm ON THE MILL for some flanged shielded ball bearings with a 4mm bore. Other alternatives are modifying the "1000 rpm motors" that everyone has been hyping about. I bought a pair (to arrive next week) and plan on swapping the motors out to the lower current drawing KW motors that normally come stock on the B16's.

And We Shall Call it... Razor Wind

2011-09-24T02:03:00.001-04:00

Last time we discussed the improvements over Safety Razor v1.1. Where are we now? Well in Atlanta Maker Faire build blitz, I built the entire thing. Lets see what images I can scrounge up.

Seeing as how there were 1-2 weeks until the event, I broke down construction into two main parts: frame and hubmotor. Ive attempted building a hubmotor several times, but never finished them. I'll be paying special attention to the motor this time.

First came the turning of the wheels. The front wheel included two facing operations and two counter boring operations for bearing recesses. The shaft was also turned from a round of 1-5/8" billet.

A stator was salvaged from a Turnigy motor. It measures 52.84mm in diameter and is planned for about 20-25 turns a tooth as described in the last post. The shaft was machined by our resident expert machinist Stephen Culpepper. A light application of glue held the motor in place.

Ever since I learned how to properly set my working zeros, my parts have come out drastically more precise with better finishes. The endcaps were First waterjet machined from 5/8" plate and then turned on the lathe. While mounting the plate on the cutting table, I realized I ordered 3" wide flat for a 3" dia part.

Luckily, I am a boss. The advantage of waterjet cutting first allows me to add through holes and a tentative bore. This way, I wont have to mount the disks on a rotary table to drill the holes.

Magnets installed. Each strip is actually composed of two magnets for a total of 28 magnets. It works, but is irritating for slow settling glue because the field on the edges repel each other.

I also spent this moment to waterjet the magnet flux rings. These were cut from 1/2" A-36 plate, epoxied together to make a total stack of 1.5". Anyway, back to the endcaps.

Partway complete.

These are probably the best pieces I have turned in my entire robotics career. The only surface I wish I could have treated were the outer edges of the flange as it still has the water jet's frosted edge.

Two endcaps with bearings were press fit in the bore of the wheel. Inside lay the waterjet style flux rings. A waterjet scrap of 3/32" polycarbonate served as a sensor mount. I figured this convenient in case I wanted to manually advance the timing of the motor.

Glued...

Wired...

Installed.

The rather large and wide front wheel of the scooter would need a custom set of front forks to account for the 2x width. Luckily, the Razor A2 frame has a "shock mounted front" aka block of rubber and hinge. I took this opportunity to create a custom mating piece that has shock absorption and a wider section.

A block of aluminum was first water jet machined to rough dimensions and finished on the mill. The raised section in the back limits the backwards travel of the hinge, the 5/16" hole is the hinge point, and the 10-32 tapped holes mate to parallel plates to facilitate the wheel.

The frame went together as quickly and easily as the old one did. This time I spent time to open up the width of all the slots by .005" such that I would have to do less sanding later. I also decreased the kerf compensation from .015 to .012 on the waterjet. The combination of both along with the use of a scrapper produced a very clean tabbing. I don't have to hammer anything together, but instead they press lightly together. The appropriate frame parts were mill mounted and drilled as needed. First a spot drill, and then a sharp 3/32 to finish it up.

Repeat. The frame at one point in time looked like this:

The main rails were together and it was beginning to take shape. A day later:

It looks much more sleek than Safety Razor. Looking at it, you could barely tell it was electrically assisted at all. Let's compare it to Safety Razor:

By late Friday evening before the Maker Faire, the lot of us grew lazy. I was intending to waterjet the throttle pieces from 1/4" Aluminum, but Charles convinced me to start rapid prototyping the remaining parts.

Among the throttle, the fan covers and charge plug covers were also printed.

The final product! Now presenting Razor Wind!

So how did it work? Well it worked well for about 20 minutes before failures began. The main problem lay in the motor. The motor seemed under specified for the amount of load required. I decided to opt for 20 turns of 20ga wire because I wanted speed, originally thinking the speed controller could throw enough current to through the motor to meet the requirements dictated by the sensors. However, this caused the motor to heat up very quickly. The heat, combined with the motor torque broke the glue joints and allowed the motor to rotate around the shaft. This effectively ripped wires apart internally and shorted some connections. The motor went up before the Maker Faire.

Razor Wind still served as a great display item along with the still functional Safety Razor. We also had some surprise scooter-wielding guests.

I have since then rewound the motor with 22ga wire and machined a small nail to act as a roll pin for mechanical locking. I am convinced the real solution would be to increase the voltage or overall size of the motor. My next solution, involves some number of these:

Dragon Con Bot Blitz

2011-09-05T19:22:00.001-04:00

Dragon Con is (technically) still going on, and Robot Battles microbattles was yesterday. I already planned on bringing Cake and DDT, but Charles, Xo, Aaron, and I decided a fleet of "Assbots" were in order. By this time it was Friday the 2nd. Isn't Robot Battles on Sunday?

Charles was nice enough to donate an old Pop Quiz frame with some motors still attached. Remove weapon motor, blade, receiver and escs, as well as one motor. Three drive motors, a sturdy frame, and a dead 4-cell lipoly. This could work.

I left my shop camera at the apartment, but the result was pretty clear.

Introducing, Prop Quiz 0.5: waaaay too light.

Seriously, that is a 3 blade prop designed for baby helichoppers. Does it fly?

YES.

Unfortunately, it had some issues expressing flight in practice.

Xo and Aaron designed a melty style robot, where the entire frame rotates to give a 100% weapon mass.

And this is how that venture went:

Looks like it would have been pretty dangerous if it was made of metal or plastic and NOT WOOD. Seriously, the only piece of material we could find Saturday evening was a 3/4" block of wood. We decided to waterjet a pocketed frame that housed all the electronics. It also weighed approximately 1lb,5oz for a 3 pound class. I just wished it had hit the opponent instead of the wall.

And here is Charles' assbot, "$20,000 per year Enjeering Degree". Of course, the robot is in the arena, not the person on the left.

A resurrected sumobot back when speed hacked servos were still valid methods of power transmission. It also had a fair number of trinkets and symbolism: "the hand is symbolic of begging for money and the weight of student loans; the duct tape wrapped around the galvanized roof flashing is representative of the challenges students face in pursuit of fulfilling their engineering degree requirements; the threaded rod represents front-end ballast mass."

The serious business robots put on a great show as usual. DDT threw robot guts all about the arena and Cake probably threw a roof shot or two. Both robots were removed by Thomas Kenny's robots, who are great in design and quick as usual. The flaws in my robots were the same as usual, and I'll probably not fix them as well.

[rumble video]

So what's next? This upcoming Saturday is the Mini Maker Fair hosted by our very own Georgia Tech Invention Studio/Maker's Club. This means this week will be yet another hectic blitz to put together the scooter I hope to feature along with Charles' equipment. Be there if you can! We promise over 60 different exhibitors, a far greater turnout than expected.

Busy on Holiday

2011-08-16T17:33:00.012-04:00

I'm currently on my two weeks holiday between work and institute but I'm kept relatively busy by upcoming events. Dragon Con and the Georgia Tech Mini Maker Faire are both coming up, which means I have about 5-6 things I need to get done.

Robots:
Running the bots at PA Bot Blast was a good way to test their metal against some real north east powerhouses but now I am left with no satisfactory running robots. Dragon Con doesn't run the 150 gram classes, but I still like to make a showing with an ant, beetle, and maybe a macro-class robot this year. I should have enough extra frame parts to revive Cake (I want to rebuild!) but the drums are just so fucked up I don't see too much in point in it. I would like to bring something different from DDT. The main idea is to not spend any extra money so we'll see how that turns out.

Costume(?):
If I go to any of these conventions, I like to put a little extra into it by dressing as something and then saving it for Halloween. As awesome as Tony Stark is, I DO NOT want to recycle a costume past a year. Hell, multiple conventions was pushing it. Right now I am looking into something Matrixy but those long coats are really damn expensive...

On to the interesting parts...

Scooter:
I bought this. Do I really need to state my intentions?

Safety Razor v1.1 is still in deployment, but I am putting foot down... on something other than concrete for braking. There are a few minor inconveniences in the current iteration that I am wanting to address in a new revision.

Braking - my left foot is unacceptable, and I just bought a pair of Nike shoes
Heft- At 13-15 pounds, the scooter weighs on the heavier side of objects. The motor alone weighs about 6 pounds, and the frame is unpocketed aluminum. All aspects of it (except the handlebars) are overspec'd.
Waterproof- it is not, and wetness has hurt it before
Switches - periodic replacement of switches due to destructive arcing is unacceptable. A precharge circuit is needed, or a high amperage switching method.
Longevity- last longer (she said that)
Smoother Rides- make it suck less when I hit cracks in the sidewalk

These are very realistic goals that all begin with the wheelmotor.

Weren't you building one already? Is it done yet? The answers to those questions are "yes" and "no". Since it isn't done yet, the logical thing would be to design another one.

In reality, I have an issue with leaving proper amounts of space for wires. I wish they were of infinitesimal thickness. Besides, that version was fitted to a 5" wheel, and as my calculations show, I can get a more efficient package from a smaller diameter but wider wheel (assuming stator also follows).

The new wheelmotor plan has lots of space for wires to route (over 1/4" of room) and a beefy 3/4" shaft for the passage of wires. The stator comes from a Turnigy motor, has a diameter of 52mm, and a length of 30mm. The stator will be wound dLRK with ~25 winds per tooth. Each magnetic pole is composed of two N52 neodymium bar magnets. All of this will be captive in a 4" rubber wheel of 40A durometer. Air gap is currently 0.6mm ideal.

To make this motor comparable to the 400W Kollemorgen , I will be routing sensors through the motor. A tad bit of trial/error is involved because I am planning on using a 150A RC car esc to drive it. Thanks to Charles and Shane, I have the pinouts of the sensor cables but I'll still be playing the mix 'n match game to determine the "A", "B", "C" motor terminals.

As a result of the motor swap, the entire frame gets a redux. The frame rails are still Aluminum but only 19" long now, and 3/16" thick instead of 1/4" before. In fact, all 1/4" plate is changed to 3/16". The top and bottom plates are still 1/8" Al, but there is no longer a garolite fancy cover plate. Instead, I am going to try engraving on some skater's grip tape and stick that to the aluminum. Also notice there are no T-nuts. All holes will be mill drilled and a silicon caulking will be applied to the inside corners to help with waterproofing.

Why don't I need the garolite cover anymore? All charge plugs are now externally accessible. A simple cover will go on top of those to prevent crud from getting inside.

What on earth is that monstrous black tumor protruding from the back? That is the model of the 150A esc. I don't actually have it on my persons yet.

Meanwhile, the battery was upgraded to a 6s1p 5000mAh lipoly pack. Super longpak!

A slight modification to the front forks to make it look less... awkward. This is the true advantage of the Razor A2 or A3 scooters.

For now, this will sit under the Safety Razor tag, but I am open to new names. Razor Wind?

I Am Otaman!

2011-08-08T01:13:00.006-04:00

This was so awesome I had to interrupt our regular posting fashion. I brought my Iron Man Costume (or Tony Stark Costume if it pleases you) to Otakon and found an Iron Man Dancer! I swear we were standing at the intersection of the dealer's hall for a good 10 minutes taking pictures.

I bet her boyfriend was wishing he'd dressed as Iron Man.

Also, this guy in the giant robot costume was a good sport. Tony Stark vs the giant robot man (Maybe an APU from the Matrix?)

Otakon 2011 Album

Last Week and Next Week (PA Bot Blast and Otakon)

2011-07-23T19:30:00.007-04:00

Finally, a weekend where I am not rushing about to see new places or compete against other sentient beings. However I have stuffs to prepare for next week so after 7 hours of straight soldering, I elect to type up a post while I am still on a solder fume high (no not really).

Made the drive from Maryland to Pennsylvania for my first ever PA Bot Blast event! Driving up to Harrisburg in the wee hours of the morning but when I started up the road to Bloomsburg things sudden looked very hilly and untouched. Towns built into the valleys of the massive hills, which were covered with trees; to be honest I felt like I was in a northeastern Costa Rica. 7 halves hours later I arrived at the Columbia Mall and prepared to set up.

I brought P150, DDT, and Cake to represent the south. I hadn't really run these robots since April, so I assumed they were in working order. Boy was I in for disappointment. P150 and DDT both went 1W:2L for seemingly dumb reasons. They both lost wheels in their first matches. P150's was removed by hedgehog's angled cutter (and P150's poor control), and DDT's seem to have fallen off by chance (when Fangus and DDT hit, he popped the belt off the pulley, jamming the blade and spinning the robot, which threw the wheel off. If Fangus was the cause, my shaft would be missing). They then proceeded to defeat robots in their expected fashion only to lose again disappointingly. Some additional thought needs to be put into these robots.

Cake made a wonderful representation! 4 wins and 2 losses, both losses caused by One Fierce Lawn Boy from Fierce Robots. Every match ending up in KO. Videos below.

The money shot of the event. The final hit between Ripto and Cake in the loser's finals match resulted in Ripto being lodged between the lexan and the outer barrier. Ouch.

Jeremy ran a very professional event. Organized procedures, match listings, and even had clarifications for the grey areas of robotic combat. Needless to say, I'll be returning if I am in the area again!

PA Bot Blast 2011 Album

Next week will be Otakon, the largely anime convention in the Baltimore area. Now, I am not a huge fan of anime, but I do like to create. I had my Tony Stark, Iron Man costume shipped up to me during Independence Day break so I could work on it. A few upgrades ensued.

First I decided to add a blue tint to my LEDs. Feeling resourceful, I merely took a marker and drew on the outer surface. Nothing fancy.

The other upgrades were all for my sanity. I redid the wiring to be much more robust and clean. At Dragon Con, I had several problems with connections breaking and repairs required. This time, all solder joints were solid, shrinkwrapped, and glued.

Textual Updates

2011-07-12T21:31:00.002-04:00

It is a loosely kept secret that I am not currently residing in Florida or Georgia this summer. As a result, summer term creativity has been pretty mute.

Some might call it slacking. I've reacquainted myself with Team Fortress 2 and all the hat(in)sanity. I've also been experimenting with this new Google+ object. Both of which I am proud to say, I HAD IT BEFORE IT BECAME FREE.

Anyway, I've not been slacking. PA Bot Blast will happen this upcoming Saturday and my robots have been ready since April. Each one of them snuggled in their little bubble wrap blankets, suffocated in duct tape. It is time to check on them.

This week I will begin cycling batteries and practice driving. I am confident each robot will put on a spectacular show, but by no means will this be an easy competition. If you are in the PA area, I encourage you to visit the event in Bloomsburg, PA.

http://www.buildersdb.com/eventdetail.asp?eventid=334

In other news, OTAKON! I've registered for an anime convention I felt like attending and so preparations begin! I had Irony Man shipped up to my location so I can work on him. Upgrades are expected. I'll be using a arduino mini instead of the Duemilanove for size and simplicity of power routing (since I can run the mini off 3.3V, and hence require only one cell). I'll also be running some Luxeon super bright LEDs instead of the current modules.

Yeah.

Enter The Wooden Man

2011-05-28T20:42:00.005-04:00

I've been becoming increasingly interested in martial arts every day. I used to practice Northern Praying Mantis in my youth and other than athletics and personal fitness it has not been too useful until I moved to Atlanta. Things are considerably more hostile and the ability to self-defense has become the aspect that keeps me from cowering in fear of the city.

Among the other styles I've seen, I've enjoyed Wing Chun. It is a southern style, that focuses on the speed from economic movements of blocking and attacking simultaneously.

I decided to try and construct a "wooden man" to help facilitate the practice of Wing Chun.
As the name suggests, these are usually made of wooden timbres with other protrusions for the legs and arms. They can be attached to the walls, or solidly implanted into the ground. As a student who travels frequently, I need my wooden man to work, but also be collapsible and light to transport around. Digging holes and hammering on my walls are unacceptable.

So here we go:

PVC body, wooden arms, and a weighted base of water similar to backyard basketball hoops. That way I can fill the base with water to add weight, and empty it between travels. The PVC construction is significantly lighter than a 9" diameter chunk of wood, but should offer enough rigidity to take impacts. Right now those are 4" PVC pipes, but I can add padding to thicken them, or use larger tube if i know they are available.

But the key features are present. The arms and legs are removable, and the base is separable into two parts to facilitate packing all the while being light.

A major determining factor will be the mating parts for the water base. I don't actually have one, so I need to first find one I can dismantle before finalizing the design.

This will be built when I return to Florida.

Supermassive Updates

2011-05-15T02:56:00.020-04:00

I neglected updating the blog for awhile due to life, but I promise this post has some good content. First, the summary:

P0w3r Drive
PA Bot Blast Preparations

Last time I assembled the endcaps to find they were wobbly by not-so infinitesimal amounts. Did I re-machine them? You bet. But this time I implemented a different technique.

You might recall, the technique I have been using to machine the endcaps was to first rough cut a disk of aluminum on the waterjet and then turn the parts on the lathe using a socket cap bolt through the center. I believed the source of the issue same from wiggle room between the starting bore in the waterjet plate and the OD of the bolt (since drill bits increase in discrete amounts not necessarily tuned to bold diameters).

So this time, I decided to apply some angular principles of self-centering. I angled the bore by using a countersink bit. Furthermore, I grabbed the appropriate flat screws for the duty and a hexagonal standoff for the opposite end. It basically worked like V-groove stands for machining tubes. The round object is guaranteed to sit in the center of the groove. Works similarly for the conical shape. This method returned a much truer endcap, and validates the technique.

Also, automatic feeds are AMAZING. Almost a mirror finish. Never before have I turned such a smooth part.

I was only able to finish one end before the term ended, so there is no way I will be able to test the wheelmotor this summer. What I can do, is wind the stator. More on that in about 12-14 weeks.

In other news, I'm finally going to fight robots again! Dreadfully Wicked Robots is hosting PA Bot Blast in the Bloomsberg Mall. Features robots from 150 grams to 6 pounds. Heavens know I don't have a 6lber, but I do have the insect fleet.

I will be taking DDT, Cake, and P150.

Wait, p150? isn't he dead? Yeah, kind of. But he can be rebuilt... better... faster... stronger...

...and more carbon-y. Seriously, lets use some of these resources I have at the Invention Studio to make some grade-A bots. P150v4 uses the old 7.4, 300mah lipoly and Jeti advance 4 esc but everything else is new. 30:1 micro sanyos, Turnigy 2204 brushless motor, HMC 3-9 single channel escs, and Spektrum AR-2 gram receiver.

Waterjetted the carbon fiber plates. Surprisingly I didnt have to use fodder plates to prevent the delamination. I just used a large lead-in, and low-pressure settings. There was some delam happening around the frame, but nothing superduper glue could fill in.

I had a moment of boredom while it was raining and decided to try engraving on Carbon Fiber. It won't cut but instead seems to melt the epoxy a bit. I guess an experience not to be repeated.

Wiring the beast is hell. I made a minor design change on the fly. Originally the robot was to use .5" standoffs to space the innards, but I opted for .375" because the motor would have required a massive hub to make up the height deficit. As a result, everything was 2x crammed in the fuselage. I had to buy the spektrum AR-whatever 2 gram receiver with the micro JST plugs to make it fit.

STILL I had to remove the micro JSTs and direct solder. [note to users: spektrum decided to be crafty and switched the positions of the 5v+ and gnd on this receiver. BE WARNED]

The HMC3-9's were angled (WTF) and flipped to fit. Only one superbus was used for power.

Somehow, it all fit.

After turning down the wheels from 1.5" to 1.125", I finished the bore on some old Vrogy blades Seth Carr of Team Lab Rat graciously donated/sold cheaply.

Bam. A robot. I added and bent some strips of grade-5 titanium to bring it up to weight and add protection. It looks very similar to Wazio's Pookie if anyone remembers that being built. Eitherway, it performs like a champ. Gryos like crazy, quicker than any version of P150, can rip through 1/32" steel like frozen butter.

Minor tune ups were made to the other robots as necessary. DDT required no additional servicing (as usual), Cake was lubricated and modified to include mechanical locks on the drum shaft instead of set screws (because setscrews suck), and P150 was rebuilt as noted above. I am concerned for the needle roller bearings in Cake because I was unable to remake the shaft so there is some audible play in the shaft. Could damage the rollers, so I'll bring the old drum as a back up.

PA Bot Blast on July. Cheers!

Also, Cheesecake.

p0w3r Drive: Cut.

2011-03-24T01:50:00.006-04:00

Mad rush to get the wheel spinning before Spring Break. It is Spring Break now, was I successful?

...haha.

First operation was machining of the endcaps as discussed in the previous post.

Mounted to the lathe through a 5/16-18 cap screw and a copious number of hex nuts. Spun counter-clockwise at about 200 rpms for something that large in diameter.

Resulting part. Pretty shiny on all surfaces touched by the cutter. I did notice some wobble produced from radial play between the cap screw and the inner bore of the plate. This must have been what Shane was talking about. We will see if this proved troublesome enough to require correction, but considering the history of this project (v1 - v2 rebuild), I'll probably end up making new ones out of frustration.

The build is progressing very well so far! All components considered, it weighs just over two pounds, which is 2x lighter than the current kollemorgen system on my scooter. Speaking of which...

Stupid things to do on an electric scooter:

Part 2 to follow.

p0w3r Drive: Sexy Things that Spin

2011-03-13T05:53:00.003-04:00

Believe it or not, but I am halfway through revision 2 of the hubmotor. You ask, "what happened to the first version?"

Simple answer: I got lazy and the aesthetics bothered me. I mean, the motor was 1.625" wide, with only 1" of filleted tread. The 1/4" endcaps looked bulky and unattractive but I couldn't add an edge chamfer because the inner diameter features were already finished. Additionally, I neglected to add sufficient wiggle gap to the magnet ring rings, which made it extremely difficult to get the magnets in place. One formerly excited afternoon transformed into a painfully disappointing sanding feat. Once I had ONE magnet in the spacers, I knew that this was not worth the effort.

So with all these changes to be implemented, I elected to simply not finish version 1. Here is version 2: incredibly badass and sexy.

The wheel is now only 1.25" wide, with a 1.5" hubshaft (more wire space, finally!). I will still be using 1/4" endcaps, but I will turn down the edges and internal features so I can sink the endcaps further into the wheel. This also allows me to rid of the polycarbonate spacers, which served no purpose whatsoever. The mechanical lock nubs were replaced with precision eyeball machining aka I will be relying on a frictional fit from the endcaps and the OD of the magnet ring. This might seem like a bad idea, but It is better than trying to use 4-40's to lock the wheel and any slipping might act as a neat clutch feature. I also added .016" of space to the magnet gap so the magnets just drop in. No file work required.

To make the endcap features, I will be adopting a trick I learned from Shane Colton. First, machining will begin with a waterjet rough circle cut. A severely undersized internal bore and the seven through-bolt holes made. The bore will have a capscrew through it, accompanied with several nuts. These nuts will then be clamped in the chuck of the lathe, and all outer features will be finished. Thereafter, the bolts will be removed, and the bore will be opened with a boring bar. More work certainly, but I expect a much finer product.

InVenture Prize: Final Run!

2011-03-07T02:22:00.004-05:00

This week is the finals round of the InVenture Prize!

Not much to say here except...

... COME TO THE EVENT! It will be held at the Ferst Center for the Arts on the Georgia Tech campus, at 6:30. Come early, get better seating.

Here's a Facebook event:
http://www.facebook.com/event.php?eid=167796909938807#!/event.php?eid=167796909938807

I am told it will be streamed live here:
http://www.gpb.org/inventure

Come please!

p0w3r Drive: Three Cheers for the Arbor Press

2011-02-21T01:04:00.016-05:00

Expecting to do some research this afternoon; did not exactly pan out. So I elected to say on west campus and do some wheel work.

The other night I tried boring one of the 5" 30A durometer wheels..

... but then it exploded. Synopsis tells me there are air pockets in the core material, and my feed rate was too high, which caused the bit to grab and toss the wheel. 300 fine for aluminum, not so much for plastic

Today, I went for round two. Turned the lathe into high gear, 455 rpms and lots of non-cinnamon (unfortunately) Tap-Magic. Like magic, we now has a properly bore'd wheel.

Posing with the stator for comparison.

Speaking of which, I put the stator hub back on the lathe and reduced part of the center mass. This would make internal wire organization easier by allowing more internal wiggle room.

Decided to tackle the flats next. Unable to find the binding screw for the large Vertrax mill, I went over to the ME2110 labs to barrow their cute mini mills.

OH GOD THE STORIES ARE TRUE! These mills really suck. I was making passes through aluminum like a pro, when I realized the mill axis started drifting. I felt like a inverted pendulum balancing robot, constantly adjusting to changes in my environment.

Either way, I finished the task, and with a half decent finish as well. Next chance I get, I'm asking my fellow studio ULI's how to tighten the collets on the Vertrax.

While I added a roll pin groove using a hacksaw, I finished preparing the waterjet, post-dredging. I want to say it would take about an hour to fill the tank manually, but since I filled it over the span of two days, nobody remembers. Similar is to be said about the number of licks it takes to get to the center of a Tootsie Pop.

Waterjet filled, cutting commences. I cut the magnet ring laminations from a 1/4" plate of A-36 mild steel, end caps from 1/4" 6061 Aluminum, and the spacers from 1/8" polycarbonate.

Ironically, the material for the spacers was the sheet of polycarbonate that was stolen from me last semester. Hmmm, how circular.

There was drilling, tapping, countersinking, and a big hand from the enormous arbor press. I declare the hubmotor mechanically complete. That leaves us in this current state:

Gathering inspiration from Iron man 2, I proceeded to wind the motor. 23.5 turns of wire per tooth, dLRK style for space savings.

Lesson learned: If you wind with anything 20ga or lower, wear gloves or wrap cloth tape around your fingers. Your writing hand will thank me later.

Completed stator winding, terminated with a Wye connection. I'll wait to see if this motor actually works before adding the sensors. This means the possible run date is the 23rd of Feb, seeing as how UPS managed to butcher the shipping of the box of magnets (routing delays).

Until then, cheers.

p0w3r Drive: Turning

2011-02-19T05:24:00.005-05:00

Late Friday night, looking to build. Waterjet is under its scheduled maintenance, so I elected to roll on over to the lathe for some quality turning time.

Feeling too frugal to purchase a large piece of Aluminum round, I pulled out a 1.25" dia round of 6061 from my scraps. Slightly less than 32mm. Shouldn't affect the system too much. I may add some anti-static tape to fill the gaps if necessary.

Post-Turn part. Drilled through with a 7/32" and tapped to 1/4-20. Chamfers with whatever degree I could find were made on outer edges. I was surprised to find a beautiful mirror-like sheen for the finish. Too bad that won't last long.

As illustrated in the model in a previous post, the ball bearing goes over that extrusion.

Radial picturage.

Next time when I finish prepping the waterjet, Ill cut the endcaps and the magnet can.

Speaking of magnet can, I elected to make a small design change in favor of using more (than one) of the 25ct bag of 2mm roll pins I bought. So here we have 7 additional 2mm holes through the magnet can rings as alignment devices.

I will probably partially press the rings together, add a gratuitous amount of superglue and press the entire assembly together. Should be solid. This part should NEVER BE SEPARATED!

Already I am beginning to find some slight design oversights. A 1/2" shaft with a 1/4-20 tap was a poor decision because that leaves very little room for wires to exit. Think of it as a 1/2" tube with 1/8" wall. My options are to make flats on three sides of the shaft or increase wire gauge. I am favoring the latter because cable organization would be far easier. I should be within reasonable current ratings in normal scenarios.

Hububububble Motor

2011-02-18T01:53:00.008-05:00

The next logical step for any piece of technology is to make it lighter, more powerful, and smaller. These goals I hope to find in the first actual hub motor I will be building.

Don;t get me wrong, I have built my own brushless motors before. In fact, if anyone recalls the first Attrition, it had a custom built 40mm motor to internally spin the drum. Now it is time to build yet another motor, slimmer, larger in diameter, and torquier (new word or sp?).

First round will be a test platform. I have a bunch of ideas on improving the sea of hub motor designs but those will be applied once I can prove to myself that I can produce one basic device.

Borrowing the techniques of Shane Colton and Charles Guan, this motor will have the following characteristics:

Flux ring is composed of waterjet stacked laminations. It will feature internal grooves to make magnet housing easier.
Stator hub is a single piece turned aluminum round. It will have milled flats on both ends to facilitate the exit of motor and sensor wires.
The motor will have three hall effect sensors to interface with the controller
Motor will be wound 30-turns per tooth, dLRK for space savings
5" OD, 1.5" wide
70mm x 16mm Hitachi Stator

Where did I get these numbers from? Charles wrote up a neat instructable with will teach you motor building basics and some sample calculations for rough estimates. Very useful and highly recommended.

Instead of featuring threads to grip a tire, I will be using a "keyway" integrated into the flux ring.

In actuality, it is an extension of the through holes used to bolt the entire motor together. I sunk in the material where there were no screws, and left the extrusions as mechanical "grips" to grooves I will be adding to the inner diameter of the cored out 5" wheel. Forces are in the correct direction, I dont expect anything pushing the motor horizontally, this should work. The number of screws might change depending on how unsafe I feel about the sheer forces on 6-32 screws.

The pile of parts has already begun. McMaster-Carr arrived today, so I received two 30A durometer 5" wheels, three 1/2" bore ball bearings, and 2mm roll pins. I already salvaged the stator from an earlier grab, and the magnet wire recycled from previous orders. The bag of 6-32 flat screws came from Cake, where I ordered a bag of 50 only to use 2. Gotta love bulk buys.

The remainder of the parts should be coming in throughout the week/weekend. Speedy Metals is expected to arrive tomorrow, which means I can begin waterjet cutting the flux rings granted the machine is not broken (oh no my baby!). I suppose then it is possible to have a rotating wheel by Saturday morning. The Applied Magnetics order is projected to arrive Monday, but gluing magnets was never a time consuming issue since it is just adding glue. I don't need to be watching the grass to know that is growing.

For the time being, project name sits at "Power Drive", or "p0w3r Drive" if you are feeling creative.

Survey: Self-Balancing Electric Skateboard

2011-02-07T00:45:00.022-05:00

Please help my team win the Inventure Prize by filling out this short survey. I promise it won't hurt!

The next prototype. Notice no hand controls, unexposed electronics, and simple design.

-22" long, 12" wide, 6" tall (wheel height)
-Weight reduced all metal frame for strength and durability while light enough to carry.
-Pneumatic wheels allow the user to silently and gently cruise over bumps and obstacles.
-Lithium Polymer batteries allow over an hour of run time with minimal weight
-Runs about 9 mph
-Rider Sense safety features prevent accidental injuries to self and others
-Customize your ride with a variety of interchangeable decks!

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If you're completely unsure about prices, here are some related products:

$550- EMAD Electric Skateboard	$160- Razor E200 Electric Scooter
$190- Sector 9 Longboard	$6200- Segway i2 Personal Transporter
$300- Altered Wombat Electric Skateboard	$760- Altered Drop Electric Skateboard

Hot n Cold

2011-01-10T17:25:00.011-05:00

By now I will be back at Tech. By now I should be starting to go to class. Instead I've been holed up in my residence because GT has shut down due to a flurry of snowfall last evening. It is pretty cold outside, but alas there is work to do: Cake's drive escs are getting too hot!

Seth at the Robot Marketplace recently informed me of a new set of KW motors for the B-series gearmotors. These guys pull more current, but are spec'd at 937 rpms at 12V or so. That is ~300 rpms over the old motors which will work great for my 1.5" drive wheels.

But if you ask me, it still feels slow compared to DDT. So lets take the motor mods a step further.

Tower Hobbies sells paired motors for direct drive foamies. 180 sized, high rpm, high current, and the correct shaft diameter. More importantly, they were on sale for a bulk buy!

The operation was a simple motor switch since the mounting patterns were the same.

Here the motors are installed with the B16 gearboxes. Ignore the new escs for the time being.
Months ago, I also purchased two scorpion mini escs to replace the damaged scorpion HX dual esc. You may recall, I had some SMT components fall off the board and while it has served me well my distrust is well placed. The two scorpion minis side by side fit perfectly horizontal in the electronics bay and open up much more room for the wires and plugs from the drum.

I applied a light application of glue on the edges to hold the two boards together, so that I could use breadboard jumper wires to bridge the main esc terminals like P0W3R busses.

Note how there are two plugs on the esc. One plug is actually for battery, but the other connects the the drum esc. Having the same connect with the same polarity makes for stupid proofing.

The real problem was that the new motors drew more current than the escs could handle. Evaluating my options, I felt that adding heatsinks was a far easier solution than disabling current limiting or upgrading the FETs. I cut some blocks of 1/8" thick copper bar (back when copper was not ass expensive) and tapped some 4-40 threads to facilitate mounting to the FETs.

A light application of silicon based heatsinking compound helps heat transfer between the materials. I also made a note to sand and polish the mating surfaces. Oxidation on the bar left lots of non-conduction crud on the outside.

Finally mounted we discover the robot to be significantly quicker, with extended runtime. I can achieve approximate 3 minutes of vigorous driving before the escs overtemp. This is acceptable.

Here is everything installed in the robot. The first picture of this post shows an unexpected benefit of adding the heatsinks. The board material fits right in between the header pins and the capacitor in my AR6110 receiver for optimal space savings!

Safety Razor Safety Advisory Report

2011-01-06T03:45:00.011-05:00

So it's been a month since I butchered a child's Razor scooter and shoved a electric bike motor system into it. Let's hear some results!

I am able to use it for inter-campus transportation with about 50% capacity drain for a full day.

That's acceptable. Especially since it is probably mostly burst amps from accelerating. Voltage has yet to drop below nominal 22.2 (for a 6-cell lipoly). I still regularly monitor the pack for increased volume, but nothing vile has arisen. The picture above shows post-charge results. We have a 66% drain over an extended run time (I had group projects across campus that evening). You'll have to excuse my camera. No flash superimposed the words "END" and "BAL" to create the illusion of "BAD" on the LCD screen.

Over a period of time, I discovered my ground clearance to be steadily decreasing. My predictions have been reaffirmed. The amount of metal removed from the original frame, combined with the hastily designed frame extensions drastically reduced the integrity of the structure. I disassembled the frame this holiday break and discovered the fracture points to lay just as I had predicted: the region where aluminum and polycarbonate met.

All of this could have been avoided by starting with a single piece aluminum frame extension. Thankfully, I am still a ULI, and speedy metals is having a 10% holiday discount until January 31. Therefore, bring in the upgrades!

From the image, you can see the back end remains virtually the same. I rotated the motor mounting holes so that the centerline from the motor shaft to the wheel deadshaft were in line. Originally, the sprocket would rub against the spacer with left from some interestingly deep erosion marks as illustrated in the picture below. Undamaged spacer included for reference. I hope you know what a hex bolt is supposed to look like.

The majority of the changes were made to the front half. This iteration does away with the original scooter frame. It was far too troublesome modifying the frame to the design and it bore little fruit other than comedic value. This body is serious business. Slots and tabs everywhere. The accessible panel has been moved from the bottom to the top. This is because repeated ground scrapings sheered screw heads which made it a pain to disassemble. Speaking of bottom plates, a UHMW skid bar will be added to take the blunt of aggressive gutters and sidewalk ramps. On top of all that aluminum will most likely be a sheet of 1/16" garolite. Just something to cover the large gaping service channel and be pretty. If it is garo, I might even consider laser engraving a graphic into the center of the deck. Gettin' fancy now...

Of course, this frees up about 2-3" of space in the scooter body, not to mention the extended width and height. This means I can opt for a BIGGER BATTERY or protection to my current pack. Both would be nice, but I may push for the larger battery in preparation for the next advancement in campus transportation: MTD (to be described in detail later).

Lots of great material coming up (but its late, and im lazy).
-BBots
-MTD
-Hardbord

I Added a Scooter to my Motor

2010-12-11T21:16:00.017-05:00

Here's the story:

On Black Friday, I bought this Razor-A scooter for $17. Now why would I waste my money on a scooter built for 5 year-olds(+)?

So I could concatenate one of these with it:

That is a 24v, 400W Kollmorgen brushless sensored motor that weighs 5-6 lbs. It is made for electric bicycles and weighs more than the scooter frame. Finally, it is larger in diameter (~5") than the scooter wheels (98mm ~ 4").

Needless to say, this is a project of epic disproportions! Yet, I still want to be manageable so I can actually use it in my cross campus commutes. Here's the game plan:

I am going to make an extended under body to house the batteries and extend the length so I can have some foot space and motor mounting provisions. Tentative model:

The wheel will be chain driven (#25) at about a 2:1 ratio. The frame thickness about the body is 1.25". The spoiler on the back is not for down force but rather acts as a foot rest because the frame is so small (seriously, the frame can only fit one of my feet lengthwise). Everything has slots, T-nuts, and delicious waterjetting. This will require major frame modifications too. The rectangular extruded frame will need to be cut on the bottom to allow the battery to hide inside. Also, some of the flanges on the side will need to be cut off because I need a flat surface to bolt the aluminum plates. Each operation removes from the structural rigidity of the frame which worries me.

Now one decision I am regretting is making the front segment from 1/4" polycarbonate. Why on earth would I make such an important part from (thin) plastic? Well because I already had it on hand. I'm in college and money doesn't grow in trees. I am worried about it bending or snapping somewhere in that region. I would run FEA on the part, but I have no idea what grade of shit-luminum Razor uses on their scooter.

Lots of pretty parts. The front of the undercarriage is made already from pre-existing plates of polycarb. Longpack and Macromotor wait in the wings...

And here is the integrand. One razor scooter awaiting cosmetic surgery...

Anyway, A lot of building happened in the span of three days and magically the project is done! My phone actually ran out of batteries so I couldn't take any build pictures. :(

Sorry folks, all you get are end result pics and video!

Sitting pretty by my fridge(s).

The throttle is a 5k pot with a shaft hub from Servo City. I should enclose those wires sometime soon.

The rear module. You can tell it is slightly different from the original CAD because I had forgotten which direction the motor spun. This made for a very disappointing initial ride test.

Closeup of the slot and tab T-Nut design. I experimented with the tool offsets on the waterjet such that it is a perfect slide with higher quality cuts. Are you proud of me Charles?

The underside. Notice where the metal becomes polycarb. I expect this region to be first to fail because it sits in between the two wheels and theoretically supports the entire rider's weight.

It has more than enough power to flip a rider over and reaches a top speed of ~20mph (calculated as 3500rpm on a 98mm wheel). It is amazingly unsafe...

... so I shall call it, "Safety Razor"

And So it Begins...

2010-11-30T20:26:00.002-05:00

http://www.buildersdb.com/eventdetail.asp?eventid=326

THAT DESERVES ITS OWN POST. TIME TO START BUILDING!!!

The fleet that probably will be going:
- P150 (defending champion 2008), 150g
- DDT (really damn entertaining), 1 lb
- Cake, 3 lbs
- Var Machine (because War Machine is a taken name), 12 lbs

Now there is a bunch of work to be done. For instance, P150 needs to be built, Cake's new drum needs to be hardened and assembled. Var Machine is still a vapor bot :/

Fortunately my good pal Richard over at MLEC might help with some machining if I drive some of his robots. Stay tuned for more!

Hardboard: Death Metal \m/

2010-11-15T00:13:00.011-05:00

So it turns out the springs won't cut it. I decided to haul the board with me one rainy day and ride it between classes. Pretty poor idea. First of all, the wide tire surface and the slickness of running water caused the board to hydroplane down some fairly steep slopes. The worst part was knowing it would happen. As I coasted down the hills of Georgia Tech, the board would oscillate violently. Turns out the springs were too soft and too responsive so a small semblance of a turn would soon be amplified to full extensions in a short period of time. I bailed off several times.

I put the board away for a few weeks and tacked other important things in the mean time. The finished Longpack for example.

I am a big fan of the blue shrink wrap. What I thought was really cool was how I could actually use the range on top of my stove to heat an area. It made me feel much safer than running a lithium battery under a flame.

The boards are in! Xo placed the order with Advanced Circuits and we received them as a strip of boards. I took a few of them with me to the Invention Studio one morning and cut them to size with the dremel tool.

The slot was also made through the ground plane to facilitate the edge of the nunchuk.

I also added some hall effect sensors to the hub motors. Three per hub motor, 120 degree spacing, attached to the tooth.

I'm not adventurous enough to try the flipped tooth method that Charles uses, although it would be much more convenient as I found out in the process.

Enough of that. THIS BOARD NEEDS TO HAPPEN NOW! I grabbed the deck and started prototyping resistive methods.

This plastic clip made from UHMW proved to be promising. The issue is that the truck angle is about 45 degrees, which means there is a 1 to 1 ratio between the person's movement and the trucks movement. With a person placing their weight on the edge of the deck, this means the resistive plug needs to exert 200-300 pounds of force without breaking or permanently deforming. Not an easy task.

Fortunately, these little guys did the trick.

These are also made from UHMW, but are taller and have additional bolt holes for more support. The older versions (also in the picture) have only two bolt holes, which twisted and widened after continual use.

What's left? Well next up is to solder the components to the boards. This should happen on Monday. My goal is to have this riding on Tuesday. How sweet would that be if I took the motor board to my meeting with Dr. Forest? =D

Irony Man

2010-11-06T04:17:00.006-04:00

Instead of typing up the entire build report, I have this comprehensive Instructable instead. I may edit it or add addtional anecdotes for the technical audience, but at this very moment, I am both tired and hungry and I unfortunately cannot satisfy both at the same time.

Here are some of the Iron Man / Tony Stark costume pictures separated by a link:

http://www.instructables.com/id/You-as-Tony-Stark-as-Iron-Man-A-Costume/

Cheers.

Like Product like Model

2010-10-20T11:44:00.003-04:00

Pretty awesome eh? I might try for an exploded animation like I had done for Cake a few posts back.

In the meantime, Xo has gotten some pretty impressive electronics work done for the wireless system. I could try my hand at explaining it, but he does a much better job than I could ever do. A trial run video will be up soon.

\m/etal power.

Moar Bord

2010-10-17T01:14:00.014-04:00

So by popular demand, the project is renamed "HÄRDBÖRD". I second this change because I did not much like calling it Fluffy, being not fluffy but still incredibly adorable. All previous references to Fluffy former will be updated to HÄRDBÖRD. I need a better way to inserting Umlauts into text...

Onto the interesting stuff:
_______________________________________________________________

Had another massive build session last night at the Invention Studio. This one pretty much wrapped up the mechanical aspects of the board. Safe to say, it is drivable by method of kick.

Last build session I had the board almost drivable except for the turnigymotors which were plain can. Yeah, not going to rough up that beautiful Chinese machining for some unenjoyable joyriding. So first operation of the evening was coring out some wheels.

Here is the invention studio baby-lathe in the back corner of the other room. A bunch of really cool automated machines sit here, but only 4 of them belong to us (CNC not included). Still this lathe is pretty sweet, because it can do the whole threading trick. Other than the standard lathe functions (gear ratios, digital readout, etc.) it has an auto jog. Woot.

Mounting the wheel to the chuck was an interesting task because the jaws were not exactly large enough to handle the object. I had to resort to the inner set of teeth and crank really hard into the soft 30A durometer wheel tread... Sounds like a terrible idea.

But it came out pretty awesome. Wheel, cored ring-o-wheel, motor can, and motor core all in one picture. A perfect slide-press fit too (with the exception of the screw heads)!

Partway through, I realized we would have to push an extra .25" deep so we could access the screw heads on the near side bearing of the motor. For this, we employed a random piece of scrap. And Arrrrrrborrrrrrrrr presssssss.

Bam, wheelmotor...and then there were two.

Two motors one truck?

Then reassembl'd.

While Xo assembled his stuff, I made a few laps around the MRDC on the board. Verdict: it works but with corrections that need to be addressed.

The springs are too soft. While the truck turning geometry is fine, the springs used to give resistance to the turns are too soft which makes the board very... "responsive". It is far too easy to over turn and drive some retarded sinusoidal board path. This probably means some design correction is in store. When I say probably, I mean definitely.

A very important but final modification to this build session was the shortening of the power pack. The stock 4Ah, 6s1p lithium batteries I purchased were 39mm tall (~1.5" +4mm) which is taller than I would have liked it. The goals for this now are to fit everything underneath the 1" square 8020 piece, which might be just impossible depending on how tall the out pins on the Maxons are. Eitherway, introducing longpack.

..and oh yes, it is very long. (163 x 2)mm long, which is over 1 foot of POWER.

IT IS A 4 AMP FOOTLONG!!!

While You Were Away

2010-10-11T15:32:00.020-04:00

Tons of stuff has happened that I will need to update later on. But for whatever reason using Blogspot makes me really lazy when I put up pictures. Anyway, notable events that need to be updated are:

completion of the Tony Stark /Iron Man costume
Dragon Con 2010
HÄRDBÖRD build report

I'm going to neglect the first two in favor of HÄRDBÖRD, because at this moment I am very proud of the current achievements. Commence build report.
__________________________________________________________

We left off at the fabrication of the board (including misc parts) and the installation of T-nuts. It was essentially a frame. As it stands right now, it is still a frame, but fanciful one with moving parts!

This semester I became a ULI for senior design (somehow) which gave me access to the fancy jumbo tools that the institution has. First and foremost is the Omax Waterjet cutter, which I have grown a close relationship too over a few long nights and days.

On Friday I began making some real parts (as opposed to other days where I would dick around with the scraps). First on the block were those 3/8" Al mounting pieces to hold the pivoting truck bars. This was a slight improv over the original design which included plastic parts. I dumped the plastic for the metal because the mill did not yet have tooling, so it would have been awhile before I could actually get to making them, and I wanted a test drive. So in my haste, I waterjet some 1" x 1" squares from a piece of scrap and end tapped them to replace the plastic parts.

Here they are installed:

that took about "x" amount of hours and by then it was probably midnight. But it was also Friday, where frankly I don't care how late I stay up because there are no classes on Saturday (just service projects and football games).

I decided to improv once again and ditch the plastic design on the pelvic bars for \m/etal t-nut designs.

It was named "pelvic thrust" in haste (is this what 4am Jolt engineering feels like?).

I was fortunate to find another scrap sheet of mystery 1/4" Aluminum to test the idea. On the waterjet it goes. Dry runs should go quicker, seriously. I didn't like watching the head move around for 17 minutes to watch for errors.

Here's a video of the cutting action:

It looks unexciting because the parts must be submerged in water while being cut and the garnet clouds the water so you can't see into it. Still there is a quaint little monitor that you can track the machining head with.

The result:

Pretty sweet eh? too bad it is messed up. Can you spot the error?

During the final minutes of the cut, a jet of water circulating through the cutting bed pushed one of the random cutouts from the piece and it hit the jetting head shifting something over. It caused the cuts to be slightly off center so the entire bottom row of parts (which ironically are the important ones) were unusable. Observe the rightmost t-nut slot for the obvious error.

I still had enough parts to assemble one leg and that is exactly what I did.

Here stands a leg fully assembled. I found out later (by empirical testing i.e. hitting it) that the mystery Al was actually 7075. THIS IS NOT SCRAP!!! Good for me :)

I finished my classes and rand back to install the motors.

I was surprised to find that the bolt holes were perfectly placed with no rubbings of any sort. With such positive feedback, I proceeded to mount it to the board.

The plastic sheets allow the board to shuffle left and right without resistance by the carpet. Story short, it works! The steering mechanism works! My roommates and I all took turns trying to see who could balance themselves the longest, which proved to be extremely difficult because there were no springs installed to give leaning resistance.

You may also assume the wheels are not mounted yet. You can actually see a wheel randomly in the floor to the north of the board. Those are 4" dia, 2" wide, durometer 30A wheels from McFaster-Carr. They came in at a pricey $14 each but should give good shock absorption, traction, and small dia (for torque).

Other Related Updates:

I just realized that I did not address the parts purchased for the project. The wheelmotors are built from some nicely sized Turnigy outrunners. They are about twice the size of Attrition's drum motor by length. The idea here is to produce the maximum amount of torque because I have a feeling we will fall short in that category. The motors may require a rewind because they are not only 280kv motors (which translates into about 35 mph no load) but they will probably draw too mugh current for the poor little Maxon DEC 50/5 modules that we plan on using to drive them.

Speaking for Maxons, Charles Guan has written up a very nice report on the use (and abuse) of these modules for brushless EV use.

Power comes from these 6s1p 4000mah Turnigy batteries. I was excited to find they they came with adapter plugs that matched the format of the Thunder Power plugs so I could actually balance these guys.

Wireless controls come from a Wii nunchuck and a pair of Xbee modules. I would elaborate more on the operation, but mush of that has been the duty of my experienced counterpart in the project, Xo Wang. All I know for certain is that it has a 5v analog output (necessary to drive the Maxons) and uses the nunchuck features to produce some damn awesome control (button enables for drive, with proportional control from the joysitck).

Also notable, I modified the design of the supports for the board. In my rush to putout the order earlier this year, I poorly designed the supporting frame members through the board. Although the center was rigid and safe, it did not extend to the trucks, which essentially left a high moment on some parts of the frame not designed to handle moments (evaluation done by my visual FEA). So here is the solution:

Replace all that metal with a single length of 8020 Extruded aluminum. Lighter and smaller in profile, with more mounting solutions. I found it a win/win situation except now there is a giant metal beam running though the center. Makes it harder to completely distribute the weight of parts but the radius from the center of rotation is so small it shouldn't matter much at all.

Left to Do:

Order Maxon DEC 50/5 modules.
Finish component storage bays
Finish second set of steering trucks
Wire, and mount
Lrn 2 longboard.

Messing With Animations

2010-09-07T23:32:00.003-04:00

Oh yeah, ispwn() = 1;

Hopefully Georgia Tech's Mechanical Engineering Department agrees.

Gulf Coast Robot Sports (6)

2010-09-03T09:14:00.003-04:00

Its been about three weeks since GCRS took place. I went back to sunny Florida and made the trek by myself (in my new car!) to Bradenton to visit the Robot Marketplace Retail store for a competition they like to host every 2-3 months.

I attended with my two main robots, DDT and Cake. In short, DDT was pretty abysmal and Cake went to win the beetles 4 wins, 0 losses.

Here are some matches.

Cake came away with the most damage it has ever accumulated (which is not very much). A lot of the hits were to the the soft steel drum, which is expected since that is the business end. I didn't expect anyone to divot it, but Voodoo Magic is a pretty mean bot. All other surfaces fared very well, offering only glancing blows for the opponent. Never was I tossed backwards by a frame hit.

DDT on the other hand, is not a fan of this arena. The low walls were to blame for all of the losses. I remember DDT doing really well in the past, and I believe it is because of the fully enclosed arena. Gosh, I really need one of those back. I will probably run DDT for the remainder of the school year and then build another ant. He has served well, but there is much to be discovered in the robot world.

Dragon Con is this weekend. DDT will have the chance to redeem himself. Unfortunately it will be difficult because the Robot battles arena also have pushouts :/

Christmas in August

2010-08-08T16:31:00.010-04:00

I finally returned home to a room filled with all the random machined parts that I ordered while I was away. Woohoo! It was a tiring ~15 hour drive, but suddenly I felt energized. Check 'em out!

Random plate for the Iron Man cosplay

Laser cut PTEG for the arc reactor diffuser

Some of these parts, look assembled. Apologies, I just couldn't keep my hands off them. :P

I was satisfied to find that T-Nut assembly is very effective. The friction clamp between the parts is more than enough to hold the pieces together. What is marginally irritating is the slight taper on the waterjet parts. This means two parallel parts attached on end might have end play of some +- .001 which is enough to make tight parts difficult. I may true the ends on a bent sander if it becomes a major issue.

Getting back to my drill press allowed me to see how the truck parts fit together. upon inspection, everything seemed to fit well. That is a thrust bearing on a bronze bushing. The bushing was a tad too long, so I will have to add washers to the thrust bearing so it can have adequate contact to the mounting block.

Look at the pretty arc reactors! I still need to prep them for diffusing light. I will probably lightly scuff the fronts of the PETG parts to give it that haze. Although 6mm is pretty thin, I am hoping it will be enough. Worst case, I'll use paper or some wide angle LEDs.

Tomorrow I am hoping to hit the local-ish surplus store for some random odds and ends needed to finish the projects. First and Foremost, I need to buy some 1" square aluminum stock for the truck pivot blocks. I neglected to order those parts in hopes of finding what I would need. If this works out alright, then I don't need to order from McMaster.

If War Machine Was a Combat Robot...

2010-07-27T23:21:00.006-04:00

... he would look like this.

I am proud to announce the final screws have been added. "Tofu" design is now complete and I can theoretically begin manufacturing.

Cheers!

Pretty Pictures

2010-07-25T20:16:00.005-04:00

Some models I designed and rendered for a friend of mine.

Not so bad for a freehand drawing. I didn't have anything to go off of except this picture.

Since we have Baked the Cake...

2010-07-23T23:46:00.011-04:00

... ferment the Tofu?
I though it a decent introduction initially but now it seems silly. Why the heck did I name this guy Tofu. I was originally going to name it "War Machine" because of the dull grey metal colors matching that of the Iron Man counterpart. But I named it Tofu as a standing name, and now the admins on the RFL won't change it. Bah. Regardless, Tofu will represent the pinnacle of my ability at this point in my career.
Tofu:

12-pound combat robot
hardened tool steel outer armor / 2024 inner frame
slotted frame pieces
single-piece stagger-tooth drum
custom integrated brushless motor technology
pioneered "stuffed drum" technique
re-engineered drive gearboxes with hot wind motor swap (maybe neo magnets)

No doubt it will be a pricey project, but this hobby is hardly cheap. Instead of cutting corners or bargaining desired features in parts like on "Attrition", I want to put in every design feature into this robot. More proof of concept than "combat competence". I basically want to make sure that my designs perform completely as intended, and leave no feature (or lack thereof) to chance. Think of it as a 8" square experience resume.

Anyway, onto the good part. Here is a render and some good pictures:

Tofu will use a few of Attrition's old parts. The BB 12-45 escs are still good. The stator and magnet can from the previous brushless drum is also still in good shape but I would like to reduce the number of turns for a higher RPM drum. The Team Whyachi MS-05 power switch is also in pristine condition but that is expected from a simple (and expensive) device. All in all, that saves about $150, so I can't complain. You are rewarded for taking care of your electronics (isn't that ironic how I am putting them through intentional abuse?).

The 32mm Transmotec gearboxes are also still good although their motor mounting plates are starting to strip out so I will have to remake them.

While I remake them I will also make them better! Here I replace the circular mount with a square one consistent with the thickness of the body of the robot. Although being larger, the square interface acts as an additional support for the motor, so the whole thing won't shake so damn much, which was a HUGE problem with Attrition. Rear motor clamps will also be added for rigidity.

The next real competition for Hobbyweight class robots will be in Feburary at Motorama in PA. Time to get started.

Note: These pictures are pretty old. I developed the designs in the Spring and have been updated since. I'll make an updated post soon enough.

Presenting...

2010-07-18T00:15:00.003-04:00

Today I am opening up 2 more project files. They may very well become integrated with each other if money does not permit, but I am very excited about getting to work. The integration of software into my designs has always been my weakness but that weakness is seeming to act as inspiration. Allow me to further describe said projects:

"Tofu"
Surveillance Robot [MICROSPY]
Innovative Car Steering System [SPEEDYCRAB]

Tofu is the improved version of Attrition, my 12-pound combat robot. Still features the spinning drum but with a few new components. Most notably different is the outer armor, which now sports .375" hardened s7 tool steel. In fact, the entire outside should be made from s7. We shall see how it holds up!

Surveillance Robot will be some mobile base with a turret mounted digital camera with can snap highish resolution photos and maybe take live feed (If I get creative). The real goal is to integrate some external radio source with the Arduino programming board and create some complex output. It is a reasonable step up from battlebots and basic circuits and certainly easier to manage than filtering Infrared signals from a TV remote (fridge bot).

Speaking of mobile base for the Surveillance Robot, I might be able to use the car chassis I am designing. Inspired by MIT's City Car project, I am trying to create a new steering mechanism to implement in existing car bodies that will allow more versatile mobility. Think Speed Racer basically. Design at this moment features 4 internally powered wheels each with their own separate steering mechanism. The steering mechanisms will coordinate with each other depending on what mode the vehicle is currently running with. Should be fun. I will be trying to integrate hall-effect sensors into conventional 2820 brushless outrunner motors so I can use them with reversible sensored controllers.

Pictures to come. Cheers!

Spirit of Building: Return to HÄRDBÖRD

2010-07-02T16:18:00.016-04:00

Not sure if I ever started a post about the electric skateboard, but here goes.

Introducing Project HÄRDBÖRD: for lack of better name. Feel free to give suggestions; maybe something about the look of the board will inspire you.

Anyway, this is a greater attempt at personal mobility devices since my electric bike. This project features:

Custom Waterjet frame
2 brushless wheelmotors with hall effect sensors
A123 cells for power
on board charging system for ease
(possibly) custom brushless controllers
wireless control via custom nunchuck controllers

I drew up the plans together with my friend Xo and together we are going to tackle this ordeal. Here is a Render.

Basically, the user holds the nunchuck controller and uses the sticks for proportional control to the motors. Ideally, I would like the buttons to do something (like underglow) but that increases power consumption for Rx and Tx.

Yesterday my parents drove up to visit and brought up the parts that Big Blue Saw had made way back when.

Turned out pretty well if I say so myself. Some minor errors [missing an extrusion and hole spacing is off], but I have been in contact with Simon ever since trying to get them straightened out.

I need to buy tools soon so I can begin putting this together. Each of the boards have a small amount of flex which both good and bad. Most longboards have flex as a natural shock absorber and turning aid but since Xo and I have electronics underneath, it would be ideal to reduce the amount of bend.

Build On \m/

Return of the Blogger

2010-01-21T09:21:00.002-05:00

Been busy no doubt, but I have returned for the time being. I just put out two blogs for GT Admissions, so why not my personal blog?

Recent items: Second Semester has begun. I am a Sophomore of 32 hours right now, with a current 18 credit hour workload. If everything goes for my summer plan in Baltimore, I will be a junior before the next year begins.

Robots: Competed and succeeded at GCRS over the winter break. First place for Cake, and non-placables for DDT and P150. Even if they had failed epically, it was still entertaining as hell :)

Speaking of FIRST, I love my Bacon

more later, I am lazy.

Another Day at the Lathe...

2009-11-11T02:13:00.002-05:00

More parts done. Nuff said.

Coming Along

2009-11-10T01:39:00.002-05:00

Alright guys, today I got my B16 gearmotors (still looking for spares however!). More importantly, I got another "round" at the lathe after the Battlebots meeting tonight. Result:

I got the front set of wheels done! I used the new design over the old one because it actually accommodated for the width of the rubber ring. I would have finished the rear set, but a guy from another organization needed the lathe for legitimate work so I'll probably go back tomorrow.

Meanwhile, I have enough parts to give a general layout. Donald and I had the same expression: That is waaaay small for a beetleweight.

Baker's Mistake

2009-11-08T17:52:00.007-05:00

Alright guys, I made my first fail part (a few days ago). This was supposed to be one of the wheels I discussed earlier today, but more of a practice than anything. I'm still pretty noobish on the lathe.

First mistake. I started from the wrong side. I started from the side that didn't need to be bored out. As a result I would have to drill through the entire piece instead of just a little bit on the correct side. No big deal right? Well I came to need to redo the entire thing because...

When I was finishing the part, I accidentally moved the wrong axis handle and ate off my pulley flange. Ugg... Fail.

Well, it still looks nice anyway so I keep it on my desk. It also helped me realize that I need to change a few things in the design anyway. The Oring groove needed to be wider for instance so I suppose this was a good mistake.

However, I did decide to use the pre-existing plastic ring. Buffer it a small bit with anti-static tape, and then fill the rest with glue. Perfect fit after dry.

Baking the Cake

2009-11-06T16:17:00.003-05:00

So last night/morning (5am) I started machining stuff for the very first time! I cut the tube, square bar, and shafting into smaller chunks using some massive horizontal bandsaw, and then turned the round parts down to the correct length. I grabbed some plastic round from the scraps bin and turned down the plastic ring that supports the flux ring. The most important operation of the night was the mods to the 2820 motor I am using for the drum. I chucked the can in the lathe and turned the endbell off. Then I had to bore the mount for the stator to 3/8" using the semi-shoddy drill press.

So this is what I ended up with for the night. Enough material for 2 drums. Everything turned out perfect except the bore for the ring was about 1mm too large. I may end up re-doing that part, or buffering it with tape and glue.

Cake - Beetleweight

2009-11-01T14:53:00.009-05:00

First there was Ron, and then there was the semi-par entertaining stand-in named Pacman. Well I let him kick the bucket last competition so it is time to get on with a new beetle and this time I'm serious...

well, kinda :P

Cake is going to be a refined version of Attrition. When I built Attrition, most of my concerns revolved around cost instead of effectiveness. As a result, the bot has a few but significant flaws that I hope to address in a downscale. Lets see if they work.

1) Integrate tabs into the frame
2) more precise drum parts
3) Reliable drive system
4) ball bearings!

With that said, here is cake as it stands. A beautiful pile of parts.

Parting is Such Sweet Sorrow

2009-07-22T13:56:00.008-04:00

Apparently it has not dawned on many people that I already have a fairyweight. "Are you building a new P150?" they ask. No, I am not. Pookie is not for me; she is for Wazio. And as such, being finally completed last night, she is currently being shipped across the United States to Wazio's place in Nevada. So here we are, final reminisces of the bot's memory. May she kick lots of male bots in the nuts.

Farewell! Parting is such sweet sorrow...

Updates: for lack of better words.

2009-07-19T21:36:00.007-04:00

Post Concert more, back to bot building and school packing. Yeah sure I have a month until college actually begins, but for me the terms are slightly different so I'll have to get ready by the end of July. Still, there are priorities to be had like finishing Pookie for Wazio.

Last report showed the basic frame plates cut and assembled with the motors and batteries placed. Well since then, I moved those around and I even wired up THE ENTIRE ROBOT!

That is how it looks right now (picture literally taken 2 seconds ago). Fully packed in, drive motors working, and with bottle cap wheels attached. It feels pretty robust and seeing it spin up, I feel like this is a quality competitor if driven correctly.

The electronics are extremely compact. I had to go thought many painstaking efforts to get everything configured the way I wanted them. I had to remove all the pins from the receiver and solder directly to the board. The PWM leads themselves were cut to about an inch long to reduce the amount of wiring running around. I even practiced board stacking where I soldered one board on top of another so save space.

You can see the "power poles" right here between the two boards.

All these modifications allowed the robot to stay really compact. (I need to take a sizing picture some day) All that is left to do is dremel the blade mounting screws off, and to make a new top cover.

Even Pacman got a makeover in time for Atlanta's Dragon Con Robot Battles event. I mounted the motor on top this time to simplify the belting system and added a self-righting hoop to keep the robot on one orientation. Don't worry, running inverted was never a good strategy so it was not like I lost anything. These new makeovers prompted a new color make over so I happily used a different color plastic and some silver to create the illustrations.

One last thin I might do is upgrade the battery for higher voltage and more capacity. After all, I do have 8oz unused.

I Have Never Been Acquanted with "Free Time"...

2009-07-17T22:23:00.009-04:00

... does he live around here?

I guess not. The past few days have been royally hectic for me. Not to suggest anything bad because they were definitely fun. On Wednesday I went out to karaoke for my friends to sing many great classics and to discover "Drops of Jupiter" by Train was not on the song list. But there were lots of things that have happened and after the dismal last few posts, it is time to recapitulate.

The Offspring concert at Hard Rock Cafe was amazing! Eric, Tina, and I arrived at an early 4:50pm while the show was actually at 8. This gave us a great spot in line. We were about 5th? For a sold out show of some 2000+ people, that is amazing. And was was even more amazing were the seats we ended up with... can you say up front and center floor!? I had a great view of the stage and the performers when they came out. It was simply amazing.

I mean, keeping that spot was another story, as there was lots of pushing and shoving. But a little bit of shifting and "counter-measures" and I was able to retain my great spot all the way until the end of The Offspring's performance. Eric and Tina were not as lucky.

But The Offspring hold a dear spot in my heart because they were the first band I really heard. Deprived of CDs and other media, I was not able to get much. But a gift from my father's friend resulted in a collection of music, where I first heard The Offspring's Conspiracy of One CD. It was an honor to finally get to hear them live and almost catch that guitar pick he threw into the crowd.

Dexter Holland is a holy disciple of punk-rock. I am serious, that is how the picture came out.

There was also the odd coincidence of seeing the sound guy on stage who happened to look like my AP Chemistry teacher from Junior year. Did we just crack open another side of Mr. Reed?

I ended the night with my favorite whopper (the angry whopper) and the purchase of two Offspring shirts. One for me, one for my brother.

The second awesome thing was the arrival of parts. My order from China finally came in, and in it came the necessary parts to finally finish Wazio's fairyweight. I'll call it Pookie in spirit of his old fairyweight.

(uh, picture later)

Really, the only part in that box for him was the motor, but it was very important and is the major part I plan around in my fairyweights. Here is a status picture of how it sits. A .1" thick titanium blade about 1.5oz will be spun by that motor at about 11600rpms on a 7.4v Lithium Battery. Drive motors are speed hacked Airtronics servos and the base materials are all garolite composites. Tomorrow I will be wiring up the electronics (Banebots 3-9 escs and Phoenix 10 esc). In either case, I know it will be underweight (weighing only 5.05oz right now) so I can add wheel guards later on.

Other goodies (11.1v 1750mah Lipoly, 30amp Brushless esc, etc.) in the box are for my new beetleweight, Ice pack, when I get to mill the frame.

Bot On! (Suckage)

2009-07-13T16:40:00.003-04:00

The last post was far too long. But this is okay, because there is not much to report on this one.

Pacman: 1 win, 2 losses. sucked
Normally I would not be this mad, but the robot did not even perform well. The only robot to have a worse outcome was my old ant Jui Kuen, but I was satisfied with him because he was a good bot. I got a great hit that sent Piranha along the hypotenuse of a 8' square. But Pacman was not one of those cases. First match, the reception was bad and as a result I was pushed out. Every other match I broke a belt after some semi-impressive hits. Even got embarrassed when I was flipped and the set in receiver high centered the robot. I will still upload the video, but something on this robot just HAS to change.

Bot On! (The Victors)

2009-07-12T02:58:00.004-04:00

Yesterday was the Gulf Coast Robot Sports competition at the Hobby marketplace down in Bradenton, Florida. And as you know, I took my three entries (Pacman, DDT, and P150) there. How did they do? Lets hit the break down.

DDT: 3 wins, 1 loss. The champ!
DDT was amazingly well behaved compared to previous outings. I kept the throttle about midway for most fights, and it kept the damage high, yet the recoil low. I might have to keep that tactic for later on. But I had only four fights because I had a first round bye and then an opponent who did not show up. So all in all, i fought against two other competitors: Piranha and Sporkinok.

V. Piranha: Piranha sported a mean vertical Ti blade directly powered by a 2212 sized brushless motor. I knew this would not be pretty, since Mike is a good driver and his bots are pretty tough. I knew wheel shots could kill me, so I decided to not allow him the chance. I lined up out blades every time and went for the "safe" impact since my blade was larger, thicker, and faster than his. He climbed DDT's front cover a few times, and flipped from some sparky hits, but soon his brushless motor had come apart and his blade bent, he decided to tap out giving me the win.

V. Sporkinok: The spork returns, but even more ridiculous than before! Now he is a 22.2v thwacker with a foot long boom of Al rod. He was fast, and almost uncontrollable, but as we fought, it didn't seem to matter... my blade was too low! It would go right under neath him, and the only thing i could hurt was the spork or the wheels. But he was so wide that it was tough, and i thought i might lose this to a judges decision. But after chasing him down, he ended up on my snout high centered, and I was able to put him out through the pit. But this was only the first of three encounters. After he beat Little Scoop in the Semi-finals, we met in the finals match 1. This time, he held a wedge attachment to try and keep me at bay. It worked in an odd way. It was enough hinderance to give a really good catch when we collided and we both flew around, with me hitting the pit. Finals match #2 started out poorly for Spork. A gyro and a change, and he was down one wheel. He tapped out giving DDT the victory.

P150: 2 wins, 1 loss. The champ!
In this I am not counting the forfeit by Nano Nightmare because I believe a fight could have occurred. No idea why he gave in though... But regardless, P150 was my second victor this competition. We ran double round robin fights in this because we only had three fairyweights.

v. Doodle Bug: I fought Doodle Bug, a Ti plated pusher, first. I spun up and he collided with me with sparks flying about. I was having control problems the whole time; the robot would go into FBS mode all too often, not like it usually does. So I suppose I got lucky, and one impact blew one of his tires out. He tapped giving DDT the win.

v. Micro Nightmare: Basically the miniature version of the miniature version of the large heavyweight, Nightmare. It sported a very similar weapon system to my own, but a slower drivetrain. I suppose I could have eaten his wheels easily, but with my control problems, he hit mine first, dropping the blade to the floor after he ripped it away. Sure I could still drive, but I was set in constant forward with the blade on the ground. At the same time, his weapon fell off, so all I had to do was stay alive! I got some light pokes at him, but an unlucky steer sent me into the pit. Time for the second string.

v Doodle Bug 2: Fighting with only one wheel was interesting. I replaced that sagging side with two nuts stacked on top of each other to give the proper blade clearance. So driving for me, was basically doing the crab walk, or using inertia to do a spin attack if he came close. There were some sparks, and some close calls when he managed to get behind me, but one lucky shot punted both robots away from the wall, where he went out of the arena, and I stayed in.

Nano Nightmare was unable to fight for the second bout so he awarded me the victory. It was a shame, I was actually looking forward to this bout.

The two victorious robots allowed me to pick up two prizes awarded at the event, totalling to $90 in gift certificates to the Robot Marketplace. Thanks to Jim, Seth, and the whole gang! I had a blast!

But now onto the big oaf...

Where'd ya go Jamo?

2009-07-10T17:54:00.003-04:00

I've been busy. That is no secret. Many of you have no idea, because I seem just as (un)responsive as usual, but truth is, I have been quite busy.

Last post, I detailed some of the tasks I had to hit for the upcoming Gulf Coast Robot Sports competition at the Hobby Marketplace. Between then and now, I got all three robots completed! Woohoo! Okay, technically Pacman is charging, but who gives...

So to knock off the easy ones first, P150 and DDT are complete. Last post I outlined the new motor mounting scheme for DDT. The motors dried in, and I slapped some tape over the back. Looks brand new and ready for combat! P150 required a little more work, but nothing strenuous. I took apart my last spare GWS PicoBB servo, and replaced the topmost portion of the casing. Then I glued the motors in to complete the robots. Some quick test drives, and charges, they appear to be ready to kick some butt!

Pacman was not as easy. After a trek to Skycraft surplus store, I bought some replacement o-rings to use as drive belts. However they were too tight! How terrible! I tried to remelt some old belts but it turned out like junk. Apparently the material doesn't take too kind to fire, and instead of melting, just bursts into flames (sorry, no pictures).

I went to Home Depot to try and get the rings I needed: no dice, they were just too small. The largest they had was about 1.25" dia, when i needed 1.5" or something around that. I was about to leave, when my mom had the brilliant idea of using bathtub washers. Sure they start out very wide, but some quick work of the sheers, and suddenly they are custom made rings!

Some additional upgrades include a nicely polished output shaft, some added flats to help aid torque, upping the size of the weapon hub set screw, and maximizing the output pulley diameter for quicker spinup times. Check it out!

To Bot or not to Bot...

2009-07-07T13:43:00.008-04:00

... that is the question.

Today is Tuesday and this Saturday is the Gulf Coast Robotic Sports competition hosted by the Hobby Marketplace. I am still trying to decide if I will compete or not. I love to fight robots, but somewhere between losing $30 (in entry fees) and my parents wanting to take me to my driver's test, it makes me second guess. Either way, I am still preparing the robots for Dragon Con in August.

First up, is my Antweight, DDT. At BARF, he did a good amount of damage, but after 5-6 competitions hte parts are wearing down. The motor mounting blocks actually fractured and broke completely on one side; into 5 pieces to be exact. I could not let this happen again.

Here are the UHMW motor mounts I created. Same overall dimensions, but the different material should make it more shock resistant. And yet, I didn't use them.

Here is what I actually did. I bought some standoffs to hold hte top armor, and then simply glued hte motors down like in some realier robots. It looks cheesy, but has actually been the best method in my opinion. No motors broken, and never has a motor come lose. It is just a pain to fix if a gear explodes.

Pacman got a weapon system change. When I got my wisdom teeth removed, I swung by the surplus store and bought some tighter O-rings so the weapon couldnt spin up faster. A lack of friction was costing Pacman some good seconds. But the O-rings were too tight. They transfered all the friction and the darn Wattage Cobalt actually sucked all of the current from the batteries. Ugg, I need another solution.

Easy solution. I changed the ratio of hte belts. The old setup was somewhere around 3:1. Decent, but for more torque, I made the blade pulley larger. Now it has something around a 7:1 ratio. This will mean lower top speed, but really, I never even GOT to top speed at BARF. Recent tests show that this configuration is a solid idea anyway.

Last, is P150. I have never introduced P150 here before, but simply it is hte smallest robot of the fleet. A 1/3 scale of DDT in a sense, definately one of hte most dangerous Fariweights in the nation.

It is in pieces... See the pretty pile of parts? Last GCRS, I foolishly put it in the Antweight rumble, where it made lots of pretty sparks, but it smashed both of its drive motors and its weapon motors. I already fixed one drive motor, but the bearing retainers on the weapon and the casing on the second drive motor are poo.

More updates to come later. And oh, the videos from the last event are uploaded on my Youtube. Cheers!

They Make "Fun-sized" Robots as well...

2009-06-23T18:51:00.005-04:00

Hey you! You haven't posted since Saturday night! Right I haven't and for good reason. First, I have my mind wrapped around a new Beetleweight class robot. For those joining us now, a beetleweight weighs 3 pounds and competes in combat competitions such as Battlebots (see BARF tags). I have spent most of my free time (and there has been much of that) CADing a new robot which is yet to be named.

Behold! The micro version of my larger 12-pound robot Attrition. The robot has a nearly 1 pound spinning drum as "x" many RPMs. Banebot 25mm, 20:1 gearboxes for drive and lots of recycled parts. Attrition was an extremely innovative and successful robot so I am hoping that this robot will also share its design success. The bad part is that I may not get started on construction because I need some larger machines available at Tech. So it it may be a few months until I can actually get started. Either way, it proves to be a fun project!

If you have any name suggestions, let me know (and you know how).

BARF in the Bay Area

2009-06-20T23:39:00.006-04:00

Bay Area Robot Fights (BARF) was today as you may remember from a previous post. In a field of 21 fellow robots, here is how my two bots did:

DDT: 3 wins - 2 losses
The crowd pleaser that never fails to please... okay I will take that back. The first match against "Babe the Blue Bot" was less than ideal because my belt for the weapon derailed like so many times past (I thought I had that fixed!). But the other 4 matches, the bot never failed to bring a smile to the crowd, bouncing off walls and making sparks and parts fly off opponents. "Cause for Concern" was one such opponent who had his 1/2" lexan frame cracked and his bolts sheered. This bouncing was the demise however when a prime hit on "Verbal Irony 4" sent DDT flying into the pit. It was only a matter of time before it happened anyway.

Pacman: 5 wins - 2 losses
We ran round robin for the beetleweights since there were no as many. Surprisingly, this robot had actually captured the crowd's heart although not being a very good spinner (belt problems, hot motors, slipping blades). The crowd, on hearing Pacman's name announced, would chant "Wakka wakka wakka!" because that's the sound Pacman makes, ha ha. I was even surprised to see that people wanted pictures of me and the robot. I will never forget this one young woman (I'm guessing early 20's) came up to me in the pits after a match and excitedly asked for a picture with me and the robot. I said yes because it would make her happy and because I was honored to know someone wanted a picture with me (plus she was, in my opinion, decently attractive XD).

But anyway! Pacman went through opponents by total win or total loss. He ate through some good aluminum pieces of opponents, a few sparks, relatively stable robot. But some really good pushers put him in the pit. Okay, one of those losses probably should not have happened, but it did. When fighting "Push it to the Limit", an impact shook off one of my wheels. But the same impact left him high centered. We freed him but i couldn't move because the loss of one wheel made the robot sit at an odd position so Pacman got pit'd shortly after. Oh well, we had fun anyway.

Overall it was a heck of a fun event. I always feel a bit strange walking into Anime conventions because the people are way too nice and energetic (and costume-y). But I really enjoy this crowd to be honest. They are overly enthusiastic which makes me feel better about the entertainment that I help provide. They really appreciate it unlike some other events.

Now I know I am not too big an anime nut, but I did see some nice costumes that I did not take pictures of. Fran from Final Fantasy (with her bow), a ton of Naruto characters ranging from Naruto himself to Sakura to Atasuki, Wong Tao Yen from Portal, and many more. I really liked the guy who dressed as the Scout from Team Fortress 2. Bonk! XD

Videos to come! I still haven't uploaded them yet. Check my Youtube page for more! And additional pictures here!

Pacman

2009-06-19T19:07:00.002-04:00

Wakka wakka wakka...

Coming to an event... tomorrow?

More pictures on my photobucket and when my mom's camera finishes charging.

Also...

Frickin' awesome!

Excuse Me, is that YOUR Bot?

2009-06-19T01:30:00.007-04:00

Up until now, I've been having people think that the giant timing pulley robot was my entry for the Beetleweight class this BARF. Well, surprise! I'm taking off the covers, the bot is nothing like expected!

Welcome to the new version of Late Night Leftovers (I might change the name to Shark Attack)!

It sports a 9" edger blade, weighing about 9 oz (I think). Total RPMs should come out around 8000-9000 which should really put a punch on the tips!

Other upgrades include more robust drive motors from my old robot "Ron". Essentially, it is Ron. All the parts came from that robot, but it is just packaged differently. Either way, it should prove pretty interesting and I'm curious to see what it can do to others, say a cake pan ;)

But you ask, what happened to the vertical disk version? I'll tell you, it practically broke it self. When the gigantic disk hit something, it made impacts tangent to the axis at a low angle. So basically, it pushed horizontally against the direction of forward motion. The friction coefficient of the tires are fairly high. So if froward forces are high, but reverse forces are also high and on the same plane, where does the force go? Into the drive motors, because it's the weakest part. Yeah, the 50:1 copals decided to burst: rather just the bushings. Either way, once they blow, I can't fix them easily. Redesign.

Here's to a good but short lived bot.

You were interesting and adorable. Farewell.

One more day till BARF. Better keep building.

BARF

2009-06-15T23:46:00.003-04:00

Bay Area Robot Fights

Metro Con: Jun 20, 2009

Ill be there competing.

Late Night Leftovers Update #2

2009-06-06T11:25:00.007-04:00

It's over. The robot was completed yesterday evening for a grand build of 2 days. This of course, is nothing compared to a previous robot of mine, which was built in 3 hours. Regardless, it is a very mean machine and very unbalanced. Let's say, most of the design is put towards the offense, making it incredibly hard to turn. If anyone wants to calculate physics here: 5" solid disk, ~11,000 RPMs, ... yeah.

But it nonetheless, works well. I think I will try it out at Metrocon, and if I don't like the results, then I will revise the main weapon supports to add maneuverability.

A shot of the weapon disk. It totals at 14.4oz (for a 3 pound robot, that heavy!). I spent 2 hours, and about 9 cutting disks shaping those titanium teeth.

How I Spend my Thursdays

2009-06-04T20:07:00.007-04:00

Last night I went to see Pixar's "Up" in theaters with my friend, Allyssa (The movie was absolutely wonderful!). Today, I relax by myself and do what I normally do: build robots.

Yes, today I spent (wasted) my time building yet another Battlebot per the Robot Fighting League (RFL). This particular robot, is a beetleweight (3 pounds) and sports a large spinning disk that spins ~10,000 rotations per minute (RPMs). What makes this robot particularly interesting is the fact that I am using all my spare parts and spare materials. It will certainly make for an interesting design because it pretty much forces me to design in reverse to what I typically do.

Anyway, I got the frame mostly complete. I'm not particularly satisfied because I usually design frames in more efficient pieces, but...

Introducing the robot whimsically named... "Late Night Leftovers"