pic: 885 Right-center wheel and drive assembly

One side of the drive train. The left is identical. The wheels happened to be custom made out of PVC, and covered in tread. The drill tranny was locked in low. Final gearing gave us ~ 8 ft per second. Using direct drive off the drills was not an ideal solution, but space was at a premium, and it proved to work out ok.

Are those wood blocks in front skids? What size, thickness, and material is that tubing?

The skids are acutally made out of a plastic called ‘stallpoly’ at the shop 885 worked at. It is the same material used to make a lot of the stall deviders in bathrooms. The shop instructor has a good source of it, and uses it in all his classes as a cheaper and easier alternitive to wood or aluminum.

It’s a bit softer then delrin, but still very strong. It also is pretty slick, as long as you take off the textured surface, so it slid on the carpet nicely. For lack of a better way of attaching them, I just threaded some 1/4 20 bolts through the frame and into a hole I drilled through the skids. It threaded right in and held them nicely, so I never bothered to change that arragnment. One skid came loose, and was lost on the field. We made up a replacement out of Delrin, and it seemed to preform just as well. I made 4 of those by eye in under an hour on a band saw and drill press. They were free to boot, which is the only real reason we used them instead of Delrin.

The rollers are thin wall aluminum tubing. I can’t remeber for sure what the thickness was, but 1/32 seems to be sound right. I’ll try to find out for sure. The exact length of the rollers varied a bit from revision to revision. I think the final length of just tubing was about 26 to 27 inchs. Including the gears and shafts, they were just a bit shy of a full 30 inches. The tubing was surpringly strong. I had anticipated having a lot of dented and busted up rollers by the end of nationals. But only one roller ever got a sizable dent in it, and we never bothered to replace it. I belive the tube came from McMaster.

-Andy A.