Economy Class Tank

thingiverse

This is a working tank model which can be used as a platform for mobile robots. Number of parts need to print: - body (needs support) or bodysupport (already included with clearance 0.5mm but may create ugly interfaces) - side x2, one mirrored (or side-taller, see below) - sprocket, axle, idler, and all gears x2 - wheel x8 - link x62 optional: - clip x4, for holding controller pcb with variable size on top of it - hanger x4 for holding battery holder - batholder for securing 2x 18650 battery holder - boardholder (with more hanger x4) for placing something I have not think about yet non printed parts needed: - dc motor, 130 size, x2 - m3 screws 20 mm and 30 mm + nuts After first try I found the tracks rather slack but if reduced by 1 link it would be too tight. So I modify the wheel suspensions to be 2 mm taller, but I have not tried it yet. I use a 3 volt dc motor with 2x lithium at 8 volt consciously, and I use PWM to give the motors about 40% duty cycle to keep them from overheating. Full power is reserved for short bursts (which I have never tried, only imagined) For fixing the small gear to the motor axle, I need to arc-weld the motor axle with 12v, 7Ah lead acid battery. With one large crocodile clip connecting the axle to battery terminal and another clip holding scrap sheet metal bit connected to the other battery terminal, I shorted the battery momentarily through the axle and the metal bit several times, melting a little from the metal bit and creating rough parts on the axle at various positions which will grab the gear firmly. Sparks were flying though, I know it is dangerous. Any suggestions? (superglue - not strong enough) Oh, and you might want to print the axles 100% solid and lubricate them. Mine heats up from the friction and twisted and bent. The solid version works so far for 2 days however.