Polycord Conveyor Belts
 

For the following questions, assume a 20" wide conveyor that is 20" long. There would be 8 strands of 1/4" polycord acting as the conveyor.

How fast can a polycord conveyor belt be run? How is that speed effected by number of turns the conveyor makes? How do you frame your conveyor and how do you keep the belts in line? What does the polycord roll around (what diameter)? What durometer polycord works well with the Fuel if anybody has tested that? Does a single run of polycord with a stationary wall work better, or does 2 powered runs of polycord work better? Does the conveyor require a significant amount of power to run, especially when loaded to capacity with Fuel?

Probably a lot of unanswerable questions, but I'm just looking for asomething much information about conveyors as possible, because I've never built one before.

Re: Polycord Conveyor Belts
 

I've used polycord flat belt for a robot combat weapon drive spinning at 10000+ RPM. No issues. I always recommend flat polycord over round as it is much easier to center by using a crowned pulley which can be easily made by wrapping electrical tape on your roller. (watch this! https://www.youtube.com/watch?v=6sM0Qjumyro)

This document has some good info on one sided conveyors vs two sided. (http://files.andymark.com/ManiupulatorDesign.pdf)

Conveyors generally don't require tons of power, usually the belts will slip on the game piece before the motor stalls.

The amount of turns don't really affect the power necessary.

Re: Polycord Conveyor Belts
 

These are some awesome resources, thank you! What specs would you reccommend on the flat belt? I'm not sure about durometer, width, thickness etc.

Re: Polycord Conveyor Belts
 

McMaster 6075K15

Re: Polycord Conveyor Belts
 

Yup, this is good stuff. Other thicknesses/widths in the same family are also pretty solid. Experience with this stuff in 2012 was wonderful.

Re: Polycord Conveyor Belts
 

How have you joined it. do you need a $450 kit to do it?

Re: Polycord Conveyor Belts
 

It's far easier to join that round belt. My favorite way is to use a hot plate (a pan on a stove works well too) set to max power. Melt the ends and then press them together. Once the urethane solidifies wait at least 10 minutes before applying tension. You can melt the faces of the belt together too if you have trouble with the ends. I've never had a properly joined belt fail.

Re: Polycord Conveyor Belts
 

The 2815 method:

Measure, cut about 3-5% short (IIRC).
Set both ends in a piece of angle, with a second piece of metal to steady it.
Melt with a small torch or lighter, press together.
Clamp tight with another piece of angle for more straightness.
Wait 10 minutes.
Try to break it by stretching; if the belt fails, you did it wrong. Try again.

Re: Polycord Conveyor Belts
 

We made a custom aluminum tip for a large 240W soldering gun and a hinged block with a slot. Heated the ends up, pushed them together in the slot and close the top of the block on them to keep them aligned. Wait until they cool and remove.

The block (along with two tiny vice grips and some other misc hardware) made a nice little toolkit that allowed us to weld these together on the robot under tension. Fixing broken belts without having to remove the roller was a big plus.

Re: Polycord Conveyor Belts
 

These are some great resources, will have to send that video along to our students.

Thanks for the reference.

Really great thread, any other tips are appreciated for those of us who haven't done belting in a while (or ever).

Re: Polycord Conveyor Belts
 

Do you think that using those belts in a vertical conveyor against a stationary wall (as OP mentions) will be effective at "pulling" the fuel balls upwards? I haven't seen a robot that has had a vertical flat belt conveyor.

Re: Polycord Conveyor Belts
 

It should be fine. Flat belt typically preforms as good as or better than round polycord. A notable robot who used that setup was 341 in 2012.

Re: Polycord Conveyor Belts
 

We were close to vertical in 2012. You'll want to prototype with difference compressions on the ball to figure out what works the best. I'm not sure whether it would be superior or inferior to a vertical round polycord system though, as I've never had a chance to directly compare the two personally. I also have only worked with it using the foam balls from RR which are not really directly comparible.

So I guess, direct answers: probably, with sufficient design and prototyping. There's also a difference between something working and something being truly excellent, and I'm not sure where this would fall.

Re: Polycord Conveyor Belts
 

469 did a conveyor like this with timing belt in 2012. If anything, the flat polycord is more grippy.