Tag Archives: hexarideablepod

recap (maker faire, hackaday and hexarideablepod, emergency nyanpancake)

I guess now is as good a time as any to reflect on my years of building things (years now?!). Hello, crackaday.
Quick note: hexarideablepod is run off of two A123 magic 12v batteries and is actually controlled by drill triggers. @__@

First, a brief interlude.

Back in the day I made some nyancakes for MAS.863. That was cut out on the shopbot from pink foam, around which I poured a full pound of easymold two-part silicone mix, aka $26.52 1lb Easymold Silicone Rubber (price has gone up since then).

one of the earlier tries. turns out it’s sad without a mold release agent, aka vegetable oil.

Kind of pricey for a single cake. Most of the silicone goes into the areas around the nyancake which can’t really be hollowed out without doing a two-part mold process. Being utterly lazy, I didn’t do that.

Well, lately I’ve been thinking that a better idea is to make cute little nyancupcake molds. So Saturday around 3 am when we were packing up getting ready to leave for maker faire, I decided to emergency nyancake.

  • 3:19am

Nancy R. Ouyang
hi charles, can i 3d print a tiny nyancake right now?
like 1” x .5 ”
if not that’s okay!
i recognize i am slightly crazily procrastinative

  • 3:21am

Charles Guan
squee squee squee
0_0 do you have the stl?
it’s gonna take like 15 minutes just to heat the machine up
i somehow think this is a bad idea 0___0
if you’re really down i’ll go heat it up right now

This actually turned out pretty well!

Files: https://github.com/nouyang/orangenarwhals-nouyang-blog-files

So then I was staying over at Dane Kouttron-wrote-own-software-for-giant-robot-arm-turned-3d-printer-currently-printing-[transportation to be disclosed] person. After getting home from maker faire I took my 1 lb Easymold Silicone Putty ($20) (putty, because since this is way smaller I don’t need to pour in the silicone) and mashed the two parts (white and purple putties) together and then stuck it into the mold. The only issue is I lost one of the eyes which wouldn’t come out of the 3d print.

The next morning, I pancaked! Using box pancake batter. This turned out surprisingly well — the pancake batter resulted in lots of holes yet it held the shape pretty well. We vegetable oiled the interior, spooned a bit of batter in, used the spatula to speed flip everything over, and let it sit for a few minutes, and then took it off the burner and let it cool to medium hot (this is a theory, that letting it cool a bit = contracts and better shape retention, and cooling too much = well idk).

ahhh one-eyed cat pancakes

Then once we got to maker faire I had this awesome idea of getting someone to 3d print me a slightly larger cake mold and ask the pancake printer people to make some pancakes for me.

Some helpful people in the 3d printer pavilion printed this out, although it finished after we left so no pancakes :'( Ah well, good shot at emergency maker faire project.

Note spider webs, sphincter compared to earlier print; need more drool control πŸ™‚ Appears to be branch from MTM snap

Okay, so back to existential crisis.

(I am totally doing this to intro all my projects so far, because I’m shameless. Also I made a portfolio recently and realized I should actually organize things).

I would count 2.007 as the first time I really started building things (which is an interesting thing in itself — does this mean I only count electromechanical things I built mostly by myself?). As usual I’m plagued by my sense of inadequacy. Because I try to point out to my friends how awesome they are when they talk about their failures and envies, I can recognize the symptoms of this cognitive distortion. And at maker faire — I got a hackaday post off of what I would call a ripoff design, when all my friends have made such awesome projects. Just at maker faire, there was Bayley and Kramnik‘s oneTesla (soon to be kickstarted), Nick’s wholly unique forging-his-own-path-at-MITERS musical instruments and tricopter, Charles’s chibikarts, Shane’s crazy motor controllers, tinykart, and quadrotor, also Ben Katz’s I’m-a-crazy-freshman (okay Kramnik is too but he’s not new to MITERS) awesome!scooter, dgonz‘s scooter and robot arm, Hunter Bank’s let-me-almost-make-an-entire-scooter-in-two-days (designed beforehand), Dane‘s crazy death scooter (pics not up yet), Ted‘s bike-scooter, and a ton of projects

oh robot hexalord all the projects

Anyway, you see what I mean? Here I’ll list out how I think about my projects. I’ll roughly list my projects in my scale of rather inadequate to completely inadequate. Mostly it’s a combination of two axis — how much engineering I put into it and whether it actually worked or not.

1) hexapod 18 servo
— failure because I never built controls / even sensors for it. Also now dead in the water because after several plane trips, I appear to have killed the pololu serial servo controller – a whopping $50 — which goes to teach me a lesson, buy things with the bare minimum I need because I’ll likely destroy it ;___; . To become legit: need to make actual (3d printed?) case for it, also figure out servo calcs instead of beast-it-and-hope-it-works as I’ve been doing. Figure out how to write inverse kinematics controls, make a GUI interface, make it dance.

2) hexaridaeblepod
— failure because I did very little engineering — almost entirely a ripoff of the epic rpalanteo instructables. Also I don’t think I’ll be working on anything other than maintenance for a long time. Well, maybe add some LED strip lights and a speaker playing nyancat, because I am apparently hexapod nyancat project person.

fewer kids than last year, also no rides the second day because I didn’t have batteries because other people’s projects ate them… ;__; the whole reason I brought hexarideablepod was to give kids rides
Also it runs much faster / scarier at 24v but I seem to be on a blowing-up-controllers spree right now.

3) Nyancake
— failure because zero engineering involved besides CADing the model.

4) persistence of vision yoyo
Failure because I never actually carried through on it and got it working (display text) with rotation, and got it to work as a yoyo. Although I did learn about charlieplexing, wrote terrible pov yoyo code which only worked when you waved the yoyo in a straight line.

5) 24v motor controller (h-bridge)
Well, I attempted to make this in 48 hours. That was a fail. I am most sad that I failed to even get to test it because I had issues with routing tiny traces under components, which the mill didn’t cut out, and also soldered the caps on top instead of poking out the bottom so I couldn’t reach the leads to solder them down. Derr. Fail. It was a simple H-bridge controller and I couldn’t even manage that despite lots of help from the thorough documentation on Charles‘s and Shane’s blog. Also it played into the pattern (yay cognitive distortion) of me not finishing final projects. -___-;;

6) Electronics vending machine
— failure because oh yea, speaking of not-finished final projects, this was for MAS.863, I made this over 48 hours — CAD’d and lasercut over 24 hrs — and I skipped the entire final class for it and only brought the half-working thing to the open house. Professor Gersheneld, I’m super sorry for taking up a spot in the class and not doing my fair share of work, although I guess in the end I am the only who lost out.

7) Random lasercutter stuff
(lab glass, business cards, clock)
— failure because, well actually I really like the lab glass present for Dan Fourie (found glass of reuse = free gift for putz cruftmas), but for the most part, no engineering involved.

gift for my friend, alice chung
clock face for what was actually supposed to be a waterjet-marble class, but I wimped out.
Cathy Wu! and anodized aluminum laser-etched..
yay fuzzy pictures. “MIT 2013, Meche (2-A), ~dream it. build it. ~ orangenarwhals.blogpsot.com”

8) Nyanweight
— failure because I intended to make a 3d nyancat, but ended up making an engraving only because I spent countless hours and couldn’t get masterworks to overlap the cuts in the right order (yay pixels = many paths ending on the same point).

speaking of which, I don’t know where i put this. oops.

9) hexapod reading group
Katy Gero took charge and spearheaded the lasercutter – bristol board – doube-sided tape replica of berkeley biomimetic millisystem’s hexapods. Cool linkage design. So again I had nothing to do with the design, although I’m happy I inspired people to make things.

credit: katy gero

10) nyantart
— failure because it is entirely a derivative of lvl1 work. Zero engineering! Yay GIMP trace of bitmap on internet!

hi lasercutter <3>

11) Metrify wireless sensors
— failure because I didn’t do any board design (all by mark spatz) — I was more business “cofounder” (no, we didn’t pursue the project as a startup, but it did help me get a job my amazing internship at fitbit). also uber thanks to startlabs for funding us and redstar ventures for hosting us.

daww generic chinese nrf24l01+ knockoff of nordic breakout board.

12) 2.008 project
— failure due to my terrible grade in that class, also I don’t feel like I contributed much to my team. I didn’t pay enough attention to lecture even though I am fascinated by manufacturing, I didn’t learn all the ins and outs of the magical mold-making process since I worked on the thermoform mold.

does it say MIT? or hell?
Hmmkay. Look, all the dumb projects I have done.

fixing the hexarideablepod shaft slipping issue

I’ve had this recurring problem where the set screws on hexarideablepod prevent the aluminum torque transmission bar from slipping radially on the shaft, but have issues preventing it from slipping axially.
Today I learned today courtesy of Mars, regarding ways to prevent axial slippage:
  • Retaining rings (clips, e-clips, c-clips, circlips) are more for axial alignment, not very load-bearing
    • E-clips are “Side-Mount External Retaining Rings” 
    • the middle part of the E isn’t supposed to go inside a keyway.
      Yea, that retaining ring I put on earlier (sticking the middle part in the keyway and dremeling an imprecise groove for the other “ear” parts of the e) wasn’t actually being that useful, although it did seem to help. 
  • Cotter pin + washer is a good solution, 
    • can probably take a hand drill even and drill a small diameter hole through the shaft
  • Even a small divot instead of a flat channel will go a long way to helping the set screws not slip around the shaft
  • I could mount a steel plate to my aluminum linkage and weld the linkage permanently to the motor shaft steel, 
And then finally the “duh” easiest solution, since I’m only concerned about inward slippage, is make a PVC standoff. 
This is super exciting, since I can finish this in 15 minutes (wellllll. If our bandsaw wasn’t out of service…. a long story… oh MITERS) and then the hexarideablepod will be mostly mechanically robust.
The electricals will be a piece of cake because I found drill triggers that are 24V 16A and make me happier than my 15V triggers. (yea, yea, I should make my own dumb motor controllers, but the packaging is just so convenient. People will even sit on turned-off hexarideablepod and play with the triggers just because). So I just need to rewire that, and make a more permanent battery mounting solution, and I’m all set.
Oh, and find another tennis ball, I lost one of my floor protectors.
Also add some 12V rgb LED strip lighting.
Next for NYC Maker Faire: 
  • hexadancingpod
    • model & print new body
    • buy new pololu serial servo controller because I am too lazy to make my own
    • build battery pack
    • buy accelerometer and ultrasound (or find)
    • write software
  • nyancat singing poptart
    • arduino + speaker
    • arduino + piezo
    • attiny + piezo -> buy surfacemount attiny’s, scrounge up piezos (get digikey account)
  • vending machine
    • add buttons
    • if time, add ir led sensors
    • ??? payment ???
  • pov poi
    • buy rgb LEDs
    • route board
    • packaging?
Other notes:

My shaft measured about 43/64” (672 mil) , so it seems like the standard given motor shaft diameters, in this case 3/4” (725 mil), is larger than the actual shaft size (? check this with someone).

Some notes I was taking:

Common ways of preventing axial slippage in the inward direction:
  • cotter pin
    • requires drilling a thin hole all the way through the motor shaft
  • retaining ring http://www.mcmaster.com/#retaining-rings/=jcg38v
    • requires machining a precise groove all around the motor shaft
    • which means if I lamely do it with a dremel (how do people do it anyway? build a fixture with a cutting edge, apply power to the motor, in a temporary lathe sort of way?) then the retaining ring isn’t going to be very strong (it’ll pop out).
    • I’m not sure about installing it since I have keyways on both sides of the shaft so it’s hard to not have one of the ends of the “e” dig into a keyway instead of a groove.

Summer: Rideable hexapod, check

teaser pic

Ah, where’ve I been all summer?

Having lots of fun, actually, but I’ve been hiding in my codefail cave and then I went and lost my camera.

Poof, hundreds of meticulous documentation pictures. Serves me right for not documenting as I go along / backing up my pictures.

Above is a pic of hexapod before I added the foot controls. Which are now being demoted in favor of joystick controls. But I did finish it in time for dorm rush / hall rush and gave lots of froshlings rides! And discovered some serious issues πŸ™‚

Hexarideablepod is based off of a very detailed instructables called Hexabot. I’m slightly embarrassed by this fact, for whatever reason, and even though hexarideablepod only deserves my love (it already has my blood, sweat, and tears…)

Yea, that’s a racecar seat that my fellow MITERSians helped me recycle from an old unfinished vehicle πŸ™‚

hexapods / summer status update

hexapod: IK, preprogrammed dancing+lilypad controls ETA end of August (2 months, pure software development)
electronics working, now apply programming
(look at trossen robotics code, implement IK)
buy things: xbee tx and rx, two lilypads, some battery male plugs + femfem servo cables, maybe a sensor or two?, maybe a ps2 controller? or accel for lilypads?, el wire, [conductive thread]
vision: sound-reactive EL wire’d body, movements depend on real-time sound input processing. lilypad
buy them soon. spend money, you can do it. o__o
mechanical: upgrade to laserjet acrylic, 3d printed, or waterjet+Al body. Put HITECs on shoulders. double-sided support. (ETA New Year ish)

hexarideablepod: ETA end of July (1 month), ideally by next week…
order steel monday or tuesday
learn welding tuesday or wednesday
CAD slightly larger version, possibly with gearing to avoid undervolting and provide more torque/power. probs not for first version… check for bolts etc.

laser-cutter: ETA end of IAP (next January)
make spreadsheet of options and commercial cost
bed size, laser wattage, commercial price & URL, laser commercial price & URL.
Then email out to MITERS.

direct-to-pcb/garment printing: requires just a weekend. maybe with Rush funding?

MITERS, lights automation and RFID keyholding, ETA last two weeks of August (begin after GSoC end).
*go ahead and order parts

hexarideablepod, until Monday July 11th (intense build during week off from CfA).

hexapod w/ IK and bluetooth, 2 weeks. w/ EL wire, 1 week. (aug 1st). w/ lilypad, 1 week (aug 8th).

Then 3 weeks left…
Plan A: MITERS personality core, 1 week, RFID keyholding, 1 weekend, rotary phone Putz, 1 week.
Plan B: make a scooter (hate walking). Last week = rush.
Plan C: start on hexaawesomepod

mysekritproject, 1 weekend sometime.


Rideable Hexapod (aka spiderbot or hexabot or whatever). Anyway, I want.

Step A. KISS. Clone someone else’s work on a linkage hexapod.

~$ git clone git@instructables.com:Hexabot-Build-a-heavy-duty-six-legged-robot/

haha I wish hardware was as easy as software to duplicate.


  1. Acquire materials
    1. Steel stock
      1. Turner Steel (carpool with someone)
        1. 60 feet of 1″ square steel tubing, 0.065″ wall ~$72
        2. 20 feet of 2″ x 1″ square rectangular steel tubing, 0.065″ wall ~$37
        3. Directions
        4. (508) 583-7800 –inquire about cost for delivery to MIT, also hours
      2. Inquire from the Central Machine Shop, bldg 38-001
  2. Apply CAD (scale up, can motors handle? torque calcs?)
  3. Apply controller to motors (make original one? probably stick with relays)
    1. schematic
  4. Learn welding (MIG or TIG)
  5. Build build build
Oh, right, youtube research: (specifically for this kind of linkage-based rideable hexapod)
Look it’s bicycle powered http://www.youtube.com/watch?v=jJY1fqzuqL0
Look it’s wheelchair motor x2 powered http://www.youtube.com/watch?v=xuRT9gC0CGs

in the meantime, I learned a bit of serial by asking Leighton, a hallmate, so now I understand the pololu code. But I still don’t understand why it’s sad. Yay I kept thinking it was something with the code, and I couldn’t find my cute tiny 2.007 battery to try . But I tried something I knew wouldn’t work, and it worked! yay. will post in pololu forums to make it more findable.