Some construction notes

Hexy Questions, Problems and Suggestions
#1

Hey Ho.

Finished building Hexy, and have been enjoying fracking around with it very much. A few construction notes for new builders. I’m sure all you pros have worked all this out already.

  • The fit of the pieces was very good, but two of the holes on the semi-circular head piece were oversized for the little screws holding the servo horn. As I mentioned elsewhere, packing the holes with a bit of u-shaped zipper cut from one of the ziplock bags worked fine.

  • After configuring the servos, and carefully entering the offsets into PoMoCo, I still find the the stock moves (like the Dance, and such) make the box-like structure holding the hip servos impinge on the body at the top. The hips don’t clear the body, which stresses the servos, as they can’t get to the extreme positions. I sanded off the square corners at the top of the hip boxes to allow them to clear the body. Now hexy is relaxed at rest.

  • Very nice of Joseph to supply a screwdriver, but do yourself a favour and use one that fits the screws a little better. With a bigger handle.

  • Instead of bolting the Servotor flat to the mounting plate, use four pieces of very short tubing as spacers under the board. The possibility of overtightening and fracturing the board is too great.

  • Ensure you center the servos by plugging them into ports 0, 1, 2 or 3 and restarting your Servotor32 board (upgraded to the latest version of the firmware) before you attach any of them to a servo horn. Attach them gently while still under power, and get them as straight as the notches in the servo horn will allow, but don’t freak out if the nearest notch is off by a degree or two. That what offsets are for.

#2

I posted the following as comments on the Make instruction page:

[quote] I found it easier to attach the servo horns to a piece before attaching anything else to it.

I.e. it’s easier to do Step 8 before Step 7, because then the piece can lie flat on your bench as you screw down the horn. Attach the horn to the side calf before attaching the side to the lower calf (foot?).

Similarly in Step 11, reverse the last two sub-steps, i.e. attach the servo horn to the U shaped piece before adding the clothespin piece.[/quote]

Also (and this may address the problem you had with oversize holes in the head/neck piece, Hellboy)

[quote]Similarly, it is MUCH easier to attach the servo horn to the semicircular piece at the base of the head before doing any of the other head assembly steps. In other words, do the first part of Step 27 BEFORE proceeding with Step 25.

  • Besides which, if you wait and it turns out the holes in that piece for the servo arm screws are too big (they’re slightly angled because of how the laser cut works), you’ll have to disassemble the head to flip it over anyway. [/quote]

Another note on the servo horns… After assembling a couple of legs, I got my drill and a 1/16 inch bit (about 1.5mm) and (carefully!) drilled out the appropriate holes in the servo horns. I still split a couple (no big deal), but getting the screws started was MUCH easier.

#3

By the way, I want to give kudos to the ArcBotics team on the mechanical design of the Hexy. Minor nits like the above aside, it’s clearly designed to be fairly simple to assemble, with only 3 different screw sizes and it is very obvious which goes where, (not like some stuff I’ve assembled where they seem to have about 23 different screw sizes, diameters and threads and six kinds of washer) and things fit very nicely. Nicely done.