Balancing a Pneumatic wheel

[team222badbrad]

Here's how I did it:

I also used stick on lead weights for RC airplane balancing, but I simply did not trust just double sided sticky tape to hold them inside the wheel.

I stuck the weights on where they needed to go and then I used 30 minute epoxy as the final balancing "weight". This also helps to secure the weights in place.

http://www3.towerhobbies.com/cgi-bin...&I=LXK204&P=ML

The fourth picture is what happens after you spend time balancing the wheel and the tire decides to spin the tube inside the wheel resulting in an unbalanced wheel...

[Cal578]

Originally Posted by ksafin

When you couple the strong adhesive and with the centripetal force of the wheel, there's no way these puppies will fly off.

What centripetal force? In the rotating frame of the wheel, there is a centrifugal force, which tends to push the weights away from the center of rotation. It's working against you, not with you. I don't know what adhesive you're using, but I would feel safer if you have a cover over your shooter wheels.

We used nuts and bolts, with various amounts of washers, at up to three points around each wheel. And a cover over the whole shooter assembly.

[ksafin]

Originally Posted by Cal578

What centripetal force? In the rotating frame of the wheel, there is a centrifugal force, which tends to push the weights away from the center of rotation. It's working against you, not with you. I don't know what adhesive you're using, but I would feel safer if you have a cover over your shooter wheels.

We used nuts and bolts, with various amounts of washers, at up to three points around each wheel. And a cover over the whole shooter assembly.

My apologies, I meant centrifugal.

I don't know how this works against us though.

Considering our weights are on the very outer edge of the plastic hub, pushing them outward away from rotation keeps them more solidly in place.

[Gregor]

Originally Posted by ksafin

My apologies, I meant centrifugal.

I don't know how this works against us though.

Considering our weights are on the very outer edge of the plastic hub, pushing them outward away from rotation keeps them more solidly in place.

And also flying out of the wheel, into the limbs of other people.

Originally Posted by Gregor

And also flying out of the wheel, into the limbs of other people.

Introducing the 2014 FRC game....

[ksafin]

Originally Posted by Gregor

And also flying out of the wheel, into the limbs of other people.

Let's talk more about the feasibility of it than joking around about it.

I don't see a way for them to fly out.

[Gregor]

Originally Posted by ksafin

Let's talk more about the feasibility of it than joking around about it.

I don't see a way for them to fly out.

I wasn't joking. I would never trust adhesive on a high rpm flywheel. If it isn't good enough to hold on bumpers, why is it good enough for a shooter?

[DELurker]

To be honest, why not put the wheel on a shaft between a pair of bearings? It takes almost all of the imbalance out of the system. Try McMaster 5913K71 bearings for 1/2" shafts...

[ksafin]

Originally Posted by Gregor

I wasn't joking. I would never trust adhesive on a high rpm flywheel. If it isn't good enough to hold on bumpers, why is it good enough for a shooter?

For one, I can't even pull the weights off with my bare hands. It's a pretty tough adhesive. I need pliers to even come close to tearing them off.

For two, the centrifugal force of the wheel keeps them lodged. I don't see any way for them to come out when you pair the two of these together.

Imagine being on a gravitron, except also being taped to your seat with a super strong adhesive. Are you going to get anywhere?

[team222badbrad]

Regardless of how you balanced your tire it is possible for anything to fly off including bolts with washers used for balancing or even the whole wheel so shield your spinning items if possible to protect from flying objects.

BTW tire shops use adhesive weights for balancing car tires.

http://solutions.3m.com/wps/portal/3...beMJV74VR9N7gl

Originally Posted by ksafin

For one, I can't even pull the weights off with my bare hands. It's a pretty tough adhesive. I need pliers to even come close to tearing them off.

For two, the centrifugal force of the wheel keeps them lodged. I don't see any way for them to come out when you pair the two of these together.

Imagine being on a gravitron, except also being taped to your seat with a super strong adhesive. Are you going to get anywhere?

No. Such. Thing.

[F22Rapture]

Originally Posted by Andrew Lawrence

No. Such. Thing.

While that's technically true, it's a convenience term for the outward force component of rotational inertia. It exists for the intents and purposes of describing and calculating behavior. You got his point

[DarrinMunter]

Has anyone looked into Dyna Beads?
There used mainly for balancing motorcycle tires. Should work for us.

http://www.innovativebalancing.com/index.php

Here is a Youtube video showing how they work.
http://www.youtube.com/watch?v=eq263AYgyYg

[ksafin]

Originally Posted by Andrew Lawrence

No. Such. Thing.

Not an actual force, but you understand exactly what I'm saying and the concept I'm referring to.

[Ian Curtis]

Originally Posted by Andrew Lawrence

No. Such. Thing.

I do not think responses like this really add anything to the discussion at hand. If you wouldn't phrase it that way when talking to your grandmother, it probably isn't the way you want to say it on CD.

As others have said, it is certainly a physics concept and being able to explain the difference between centripetal and centrifugal force is a key indicator that you understand what a reference frame is, and how they work. In college, particularly in Orbital Mechanics or Mechanism design this intuitive understanding becomes very important as the vector math gets real crazy, real quick. Any good physics textbook should have a reasonably in depth explanation, an old xkcd comic does a decent job in a blurb, and of course Wikipedia goes into much more depth.