Shooter Wheel Expansion

Our team is currently using 2 of the 60A 5" straight flex wheels for our shooter (https://www.vexrobotics.com/flex-wheels.html#CAD_Files). We get a fair bit of expansion for the wheels and I was wondering what teams are doing to calculate or measure their wheel expansion to work out flywheel weights. Thanks!

Most teams are not using compliant wheels for flywheel shooters. Andymark rates their 4 inch compliant at 3650 rpm. I assume VEX’s numbers aren’t far off. If you were to use a compiant with a NEO at 1:1, the wheels is going 2000 rpm over what it is rated for. I would try using something like a fairlane compliant wheel, or a Colson wheel.

It make go boom. Not go good. Be no use compliant

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The Fairlane compliant wheels are even worse than the AM/VEX compliant wheels. You’ll want a solid Fairlane wheel. Yet even with those, consider adding some safety wire.

1678 has produced some great videos:


Also, here is a recent relevant thread: Flywheel Do's and Don'ts

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Do you have a link to where you found these RPM rating from? based on our own testing and this chart it would appear out wheel are rated up to 9k RPM (assuming similar numbers) https://andymark-weblinc.netdna-ssl.com/media/W1siZiIsIjIwMjAvMDEvMjYvMTIvMjUvMDEvZjBmNDhkYjctNjZjZS00OGNlLWIxMzItMzZjYjJlMTkxY2JhLzQgaW5jaCBDb21wbGlhbnQgV2hlZWwgRXhwYW5zaW9uLnBkZiJdXQ/4%20inch%20Compliant%20Wheel%20Expansion.pdf?sha=be124c0b898f07f5

When prototyping with the black compliant wheels what we saw seems to match that chart for ~5krpm. We are still not going with them though

Thanks! What drove you away from compliant wheels?

I am honestly not sure why you would want to run compliant wheels at all in a shooter this season. The balls power cells are pretty compliant as is, especially when there are a few holes poked in them. From there it is just a matter of adjusting compression to find a balance between aerodynamics, shooter rpm recovery, and exit velocity. All doable with slight alterations to the hood/flywheel geometry.

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Keeping the inertia up during the shots. We found that an aluminum drum coated in the KoP grip tape worked really well. It fit the soft game piece hard wheel model we liked and keeps the packaging small. 0 expansion keeps the compression consistent.

Not too concerned about the cheeto dust on the wheel as that’s after well over 1000 shots

What motor configuration are you using for that? we leaned away from 4" wheels due to the loss of surface speed being transferred

We have looked at 1 Cim, 1 Mini, and 1 Neo all direct drive. We are going with the Neo now, about 5k rpm gets us shots from a safe spot in the trench when we have a deflector on top (holding a piece of plywood at the top). Without that we can shoot from against the wall in front of the goal. Still not a final rev. RPM loss per shot is I think ~200 but recovers fast enough for 2-3/sec with some SW

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