More Tips & Tricks from Todd: PVC Rollers & Motors

Recently, Todd Lovelace, mentor of Team Resistance was asked the following questions:

1) I’m sure you guys have tested the PVC rollers/poly cord on these new balls. The balls are a bit heavier than in the past, but does that system still work? 

2) What motors have you used for the rollers? I think we’re sticking with 4 CIMs on drive, the 2 fisher price (possibly 2 FP and 2 banebots on the turret). Would a L/R window motor or a banebot give those rollers enough speed to handle these heavier balls? 

This was Todd’s entertaining and highly useful reply:


Polycord will have a great capability to carry these balls. Be sure to stagger the rollers that the cord runs on to keep from trying to squeeze the balls while carrying them.

We are also reserving the CIMS for brute force with great reliability. We have not chosen the rest of the motors yet.

You will want to size the motor/gearbox speed on the conveyor so that the linear surface speed is the same as the circumferential surface speed (Pi*D of the roller x roller RPM) in feet per minute…ie, the surface speed of the roller in feet per minute will be the same as the conveyor cord speed and the ball-thru-the-machine-speed. The window motors are very slow with lots of torque, you will likely want something faster with less torque.

The floor pick-up roller circumferential speed needs to be about 20% higher than your top robot floor speed in feet per second to be sure you snatch the ball into the machine before it has a chance to bounce off your pick-up roller.


Note the criss-cross belting for roller direction reversing…….

Don’t let this happen to you.

The worst team member ever……and what an annoying sweatshirt.


Got more questions for Todd? Drop him a line at   19 more build days to go!

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