no tensioner 8 wheel belt drive: tooth skip ?
 

If you accurately drill bearing holes using WCPs belt distance calculator and the 2 cim transmission power is split between 2 belts (each to a wheel and then to another wheel via a 2nd belt) and the bot is driven aggressively (ie can push and be quite fast) and the wheels are cantilevered immediately off a frame (as opposed to supported at both sides by a frame)....

Will the 15mm belts (on 24 tooth pulleys) stretch enough over the season to need a belt tensioner or replacement (else they skip pulley teeth) during the season ?

I'm also concerned the axles with its 2 bearings (in a 1" wide frame) might twist slightly introducing slack in the belt leading to tooth skip.

I heard at least one team say theirs lasted the season with no tensioner and no belt replacements. What was your experience (how many wheels, cantilevered or not, belt type, width) ?

Thanks

Re: no tensioner 8 wheel belt drive: tooth skip ?
 

If you have not done it before, I would recommend against it. Your drivetrain alone can score you many points, and an inoperational one could shut you down this game.
I know many teams have done 24t 15mm before with success, but I don't know how many used direct C-C distance or how much they added/subtracted to the distance.
What do you mean by "accurately drilling"? I would definitely not do this with a drill press or something.

Re: no tensioner 8 wheel belt drive: tooth skip ?
 

ways to mitigate this potential problem would be to increase your pulley size. Not sure how you intend to hold your bearings on your drive frame tube, but the best way to strengthen your bearing set up is to 1, use a support plate, 2, move your bolts to almost tangent to the inside wall of tube (on 2x1x.125 tube this is roughly .25 from the wall with a 10-32 bolt). This allows you to clamp onto the tube with more force. 3, locktite your bearings into the tube.

Re: no tensioner 8 wheel belt drive: tooth skip ?
 

WCPs belt distance calculator gives center distances to at least 0.001. We have a small mill that has similar precision. So we can place the bearing holes very accurately based on what the calculator tells us.

Re: no tensioner 8 wheel belt drive: tooth skip ?
 

All great ideas. Thanks
Time for a prototype!

Re: no tensioner 8 wheel belt drive: tooth skip ?
 

We have run this setup with no failures before. Bearing holes were created via a laser cutter.