I’m curious about what other teams are using for rollers on their intake system for 2014.
I’m primarily interested in custom made rollers and what has worked best for controlling the canvased game ball. (Any experience from 2008 is also welcome).
So here are my questions.
What type of roller material are you using?
Was it expensive?
How are you driving it?
Are you using some type of traction material on it?
If so, what type?
Are you using polly cord?
If so how are you controlling the pollycord? (Lathing grooves, building up area around the cord)
Are you using wheels?
If so what type of wheels?
Thanks in advance!
As soon as we got the ball into the shop I did the good old touch stuff to the ball test. I highly recommend doing this test around your own shop. We found that the BaneBots wheels, which are relatively inexpensive, gripped the ball best. They are also particularly nice because the ones we have are hex on the inside. All we have to do is run the shaft through them and drive the shaft with a motor which is chained to a sprocket, also hex, which sits on the shaft, and we have our roller.
I hope that helps.
Our tests showed the two best materials for gripping the ball were Banebots wheels and sorbothane. We went with Banebots wheels because of the hassle of installing and cleaning sorbothane tread wheels, but we will use strips of sorbothane elsewhere on the claw.
Where do you source your sorbothane? Is it this from mcmaster or is does it come in a more convenient form (rollers,wheels?)
Otherwise we were considering 3M gripping material or the McMastered rubber strips that Boom DONE used.
We’re finding some success with the DT versawheels on our intake. For smaller diameter rollers though, we use Polyurethane tubing found here. This material is very grippy, and can be compressed quite a bit as well.
My team machines our own conveyor rollers. In prototyping we used 2 inch OD PVC pipe and machined hubs that press into either end. We drilled two holes through the PVC drum (at either end) and spiral wrapped urethane cord (AKA polycord) around the roller using the holes as positions for anchoring the ends. It worked beautifully. On the final bot the rollers will be made with .065 wall aluminum tubing instead of PVC.
Like others have said, BaneBot wheels are awesome. Back in 2008 (before Banebot had wheels, I believe) we did custom rollers - plastic wheels with some sort of foamy rubber glued on. It was a huge mess though - the rubber was constantly coming off in chunks, and we had to have a couple spare sets of wheels so we could swap them out and fix them with new rubber. I would definitely go with a more off-the-shelf solution!
This was our original thought.
After some testing we noticed that there was a weird spin on the ball and concluded that it was because of the larger wheels spinning faster than the smaller wheels. To solve this we settled on using the 2.875" wheels all the way across and it works much better.
We are using rubber jar stoppers that we got at our local hardware store. They have a slight bevel and are about 2" in diameter. They are working well in early testing.
We use 3" black ABS sewer pipe with some grey 3M bathtub anti-slip tape wrapped around it. This stuff is found at some Ace Hardware stores in various widths, sold by the foot. It’s not the black sandpaper stuff, but rubber with a high texture.
We drilled bearing holes in the end caps on the lathe. Our nice build space, Xerocraft, has a shiny new 7/8 drill bit lying around, bless their hearts.
This is what we ordered. We got the 1/4" thick stuff. To install it on a wheel we just wrapped it around the wheel, held it temporarily with masking tape, used a pokey tool to stab rivet holes into it, and used big head rivets to fasten it. A strong contact adhesive may be a better idea though.
How can you secure the wheels in place on the hex shaft? AndyMarks is out of stock of the hex shaft collars.
4183 is using ABS tubing because it works, and it is so easy to work with.
We are using PVC spacers to keep the spacing between the wheels and turned down the ends of the hex shaft to fit in 3/8" bearing blocks and collars.
Here on thingiverse is a scad for 3D printable shaft collars that will accept Hex Shafts.
We have also developed this scad for shaft couplers:
I would print this in Nylon however and on it’s side as hex for strength.
The parametric wheel was used to create spacers.
Depending on how well your printer is calibrated I use 13-14mm for the shaft diameter to fit the 1/2" shaft snugly.