Re: Andymark Pneumatic wheel problems
 

Our tire that we put the tube in refused to seat correctly, even after the hub was coated with a little water/soap and pumped up. I think its just part of the wheel coming off the line.
Our other wheel we put pool noodle in, and it seated pretty well and was pretty well balanced, but wasnt solid enough.

Our motor mount is pretty much all screwed down, and the wheels are supported from both sides.

The answer from everyones' replies seems to be that these wheels just are not rated for what we were all trying to make them do. i think most teams saw IR3 using them and jumped to the assumption that we made ourselves, which was that they worked, and worked great. And as IR3 showed in the videos, they do- to a point. Stated somewhere above is the (so far) unproven statement that they were scaled to 60%.

Team 225 has moved on from these wheels, and it sounds like most other teams have as well. Good luck to all of you finding replacements, and if you get really stuck, pm me- we have a few ideas that we can share.

Re: Andymark Pneumatic wheel problems
 

Pizza,
The filling of the tube is what is needed to seat the tire on the wheel. In some cases, as you fill the tube, you may need to compress the outside diameter of the tire to get it to seat on the wheel. Once it appears to be seated then you can fill it the rest of the way.

Re: Andymark Pneumatic wheel problems
 

Has anyone done an analysis (using the high-speed videos or any other method) of how much slippage there is between the shooting wheel and the disc? In other words, by the time the disc is exiting the shooter, has it accelerated enough that the two surfaces are no longer rubbing?

And if you do have this answer, then:
1. What material is on your shooter wheel?
2. What size is the wheel?
3. How fast is the wheel spinning?
4. How much travel does the disc have with the wheel? (90 degrees, etc.)
5. How much compression are you using?

Re: Andymark Pneumatic wheel problems
 

1. Rubber AM Pneumatic wheel with extra mass (saw blade grinded down)
2. 7.5" - No air inside of the tire
3. 80% controlled via programming
4. 90 degrees
5. Not much, the frisbee sits under the wheel and on top of our wood prototype, it follows a track around (c-channel).

I'm still compiling some data and I hope to post it later tonight. I'll include multiple pictures of what our prototype looks like, how we load the frisbees and (hopefully) some velocity measurements.

I do not have a clamp-on ammeter as my college will not allow me to borrow theirs, so I will not have current readings. However I will post voltage readings.

Re: Andymark Pneumatic wheel problems
 

What control algorithm are you using?

Re: Andymark Pneumatic wheel problems
 

Thanks for the data.

80% of what? What motor are you using? If we know the free speed of your motor, and if you're running it at 80% voltage, then we can estimate the speed of the wheel (subtracting a bit because free speed is idealistic).

Re: Andymark Pneumatic wheel problems
 

Team 225 has successfully solved this problem by removing the inner tube from the tire, and replacing it with pool noodle. This provides a strong, springy, balanced wheel that spins beautifully.

Good luck!

Re: Andymark Pneumatic wheel problems
 

We found that part of the problem was that as the wheels rotate, the valve stem is pulled outwards by centrifugal force, making balance much worse.

We solved this by putting a zip tie around the valve stem and the bolts holding the wheel to the hub. After that we had no problems and the vibration level was quite acceptable.

By the way, frisbee launching speed does not seem to be linear to wheel speed. We found that our best launching speed came at about 3000 rpm. Probably each shooter is a little different though.