Re: Keeping polycord on track
 

Your problem might be caused by having so much polycord. The tension of it could be causing the pvc to bend in towards the middle. This would cause lots of jumping. We experienced a similar issue in 09 so we stuck a piece of aluminum L the size of the inner diameter of our pvc through it to straighten it out.

Re: Keeping polycord on track
 

That's a neat idea!

But I think we're doing something wrong on ours, we only have one set of polycord belts, and two rollers, to do the whole harvest/lift/load-into-the-hopper thing.

Re: Keeping polycord on track
 

I very seriously doubt if you're doing anything "wrong" :) , just make sure that multiple balls don't bind up on each other as they roll against each other.

The balls generate a lot of friction when they try to roll against each other. We've had bad experiences with single-feed systems with multiple balls binding up which led to our "dual lift" design with cords on front and back where the balls don't roll against each other.

Your system probably works better than ours if it's engineered correctly!

Re: Keeping polycord on track
 

No, we do have the problem with multiple balls being able to easily jam in the intake. It's neat to see how you solved that problem.

The main reason we don't have much stuff on our robot, is because we're lazy....we'll spend hours figuring out how to avoid making more parts!

Re: Keeping polycord on track
 

In FRC applications, you only need 3-4% stretch.

Re: Keeping polycord on track
 

We just put our polycord on last night and it didn't seem to have a problem. We're using pvc rollers wrapped in shelf liner which creates enough friction that the belts don't move side to side.