Tank Treads?

[artdutra04]

Originally Posted by reversed_rocker

We were thinking of making tank treads to drive our tshirt cannon as an off season project, does anyone have any experience with this? We just wanted to see different ideas and how they worked for other teams

Do you want to drive it offroad, or just want to have tank treads for the cool factor? I ask, because whether or not you want to drive it offroad will affect a lot of design considerations. (Dirt, rocks, water, mud and temperature fluctuations would now be design considerations, and the surface friction is much higher)

If you are sticking to mostly indoor or asphalt/concrete surfaces, something along the lines of Brecoflex belts may be a good idea. The one downside is that they are expensive.

For our offroad promotional air cannon robot, we used a kid sled-size snowmobile tread cut down the middle. We had to use some kind of tread with "teeth", as one of the design goals here was to use something that can drive through snow. The advantage (and problem) with using snowmobile treads is that they are very stiff; meaning you will lose a lot of mechanical power just making them spin. On the other hand, they are impossible to detrack without disassembling the bogies. To power these treads, we designed custom six-tooth sheet metal and Delrin sprockets because the only stock ones available are four-tooth sprockets. These are insanely small, and require an unbelievably high amount of tension to wrap the snowmobile tread around something this small. This would rule out all but an ICE for powering the drive train without breaking the budget

Combine these treads with having lead acid 12v 18Ah batteries onboard (11.1v 10Ah LiPo batteries are ~$300 versus about $40 for 12v 18Ah Lead-Acid), an air compressor for shooting, and quite a large onboard sound system (this draws a lot of power - about 160 Watts - being constantly on!). Added up, this results in a drivable maximum range of about 200 yards, or about an hour of just playing music while firing off a few shots every now and then.