Hex wheel hubs for 3mm and 4mm D shafts

thingiverse

I use these hex wheel hubs in my 150g and 1.36kg/3lb combat robots, on N20 gearmotors with 3mm D shafts and GA25 geamotors with 4mm D shafts. I then cut foam (ie from kids playmats, flip/flops and the like) or rubber wheels of whatever size required and cut the hex hole with a knife. Both types are designed to be tapped for M3 grub screws on the sides to keep them on the shaft and for M4 bolts at the ends to keep the wheels on the hubs - a stl for a washer is also included. These wheels are adjustable in size, lightweight, cheap, and hold up really well in combat.