Large scale (75mm wide) caterpillar track

thingiverse

This is a large scale track, 75mm wide x 1" pitch, intended for medium to large robots or tracked models. It is designed to run on ISO16a or ANSI 80 standard sprockets - metal or plastic, as preferred. (I'm using printed sprockets based on a design from Cults3D, with the hubs adapted to fit my motors & bearings, so I cannot publish those designs - you can find them here: https://cults3d.com/en/3d-model/tool/ansi-80-roller-chain-sprockets-with-hub ) UPDATE - I've added versions of the inner and outer link that have matched, flat, upper surfaces so rollers can be used for idlers rather than only sprockets. These also make the appearance closer to conventional bulldozer tracks. For maximum life, the chain pin bearings and rollers use bearing bushes, with steel clevis pins joining the links. The bushes I used for the pins are 6mm bore, 8mm o/d by 5mm long for the outer links and two 10mm long for each end of the inner links. I also considered nylon or PTFE bushes - 5mm and 20mm sections of 8mm o/d x 6mm bore nylon pneumatic tube could work for the pin bushings, and 16mm o/d x 14mm i/d tubing is available in some kind of plastic - eg. PTFE. 15mm sections of that could work for the roller bushes? Edit - I've just printed a tread plate in TPU (previously untested / WIP) and it was a perfect push-in fit to the sole of the outer link. Photos added. That was printed with 50% infill and is still very stiff, so I think it could have been OK at 20% - I will try another at that. The outer pins on the tread plate protrude through slightly. I did that so they could be melted over to prevent being pulled out, though I don't know if that is needed. If you want to try it, a "clean" way it to put a piece of aluminium foil over the area to be heated, then gently wipe over the area with a soldering iron until the part has flowed enough. It creates less fumes than direct heat from an iron, and does not mess up the iron tip!