Team 3992 Launcher - Help w/ Vibration?

Hello all.

We just recently got our launcher working to the distance and height we’d like:

However, as you can see, there’s IMMENSE vibration which is moving the frame and keeping us from being consistent.

Any suggestions? Some issues we think may be causing this:

  1. Pneumatic wheels aren’t true (even) they have some kind of wobble to them.
  2. No bearing/support at the top of the shafts for the wheels

Thoughts? Suggestions?

You’ll need to balance them. A heavy bolt or two through the hub, opposite the valve stem, might be a good start.

Awesome prototype! How far away from the shooter is that wall?

How accurate does it shoot at close range?

What speed are you running the pneumatic wheels at?

I agree with your suggestions about the lack of support causing vibrations.

This video gives some suggestions about balancing pneumatic wheels:

Does it also have to be inflated all the way to 36 psi? Like, will any less than essentially maximally full cause unbalance?

I saw the Lunch with Andy episode and will do that though; does it have that significant of an effect?

The wall is about 50 ft from the shooter, and the frisbees hit above 20 ft in the air (the lamps are hanging at about 21 ft).

We never tested close range; this was a test on friday night and we haven’t been back since.

We’re running them 1:1 on CIMs.

It might be a good idea to mount the wheels on gearboxes (such as the upcoming SpinBox) rather than direct-drive. The CIMs don’t have much internal structure to prevent vibration.

It sure does, especially at high speeds. And if it’s balanced properly, you might be able to let most of the air out, and this will allow you to have the wheel compressed more on the Frisbee, giving better performance (because it gets more friction).

This is my favorite demonstration of why you need to balance things that are going to spin fast.

We have had good success by placing 0.75 oz of stick-on weights (Harbor Freight or other places sell them) in the open space on the plastic wheel hub , directly across from the valve stem. It made quite a difference without doing anything else.

We had the same problem when making our shooter. I would greatly consider connecting your motor(s) and wheels together with a chain or belt via sprocket or pulley. It greatly reduced ours because the belt took away a lot and then we looked to extra bracing. Balancing the tire was the last thing we did. Hope this helps.

Just make sure that they stay stuck on at speed. I would think you would need a mechanical fastener or over time the glue will creep and you will have a projectile…

The pneumatic tire hubs have a pocket (void) where the weights with sticky tape can be placed. The spinning wheel just forces the weights against the inner part of the hub, further securing the weights. There is no glue involved, just the stick-on weights used to balance car tires.