I have a plastic spinner that I think is out of balance. Is it possible to balance a spinner and if the answer is yes how do you go about doing this? Is there a method of using a prop balancer to achieve this? Thank for any advice and suggestions.

I balance the rear part of the spinner on my finger balance by turning one of the nuts backwards - ok, well I have done that, not sure if I have on my last two planes

Clear nail polish is a great way to add weight to the lighter side of a prop for balancing, so it would work on a spinner too.

My humble opinion (which lacks experience but not insight) is that even if your spinner is out of balance, it's mass distribution is pretty close to the prop shaft and therefore shouldn't cause an absurd amount of vibration - not as much as a prop that was out of balance. Is it THAT bad? There are a lot of people here who don't even really balance a prop, so I'm sure they'd all say to not worry about the spinner. Guys who are serious about smaller details would probably say to toss it and get a Tru-turn or something.

Well, let's see if I'm right...

I'm one that enjoys ALL the details. And one day, when I was about to open up the holes in one of those turned spinners, I decided to check it's balance before doing so. (It's going to get checked after opening up for sure, but wanted to see beforehand just how perfectly those perfect things are.)

It was out of balance. So I checked the backplate to see which part was out. It was out, and the front was out. It dawned on me that to get them both balanced, I'd need to do the backplate first.

I've checked them all since that day, and have yet to find one balanced. Does that mean they all need to be checked and balanced. Truth is, nope, not even. They aren't props and don't have the leverage a bad prop would have. And I've yet to see one of the turned spinners that came close to being as bad as props can be.

I actually look at balancing those little babies as a way to prove the balancer's accuracy. And balancing spinners is the first anal thing I do that I'd quit doing. That is, if I didn't enjoy this hobby so much, every bit of it. BTW, I don't bother to balance plastic spinners. They're so often less than aligned, what's the use.

Yes we thought that the spinner balance would not be to much of an issue as the mass of the spinner is close to the centre of the engine and as you say nothing like an out of balance prop. However two different balanced props and the vibration is still there. The plane was supposed to have a 20 engine and it has a 29 OS engine. Is it possible that the larger engine could itself be causing the problem? Surely if the larger engine is not run flat out and the plane is balanced the larger engine would not be an issue?? Apart from the severe vibration the plane flies really well.

It might be the larger engine versus the very light, smaller airframe. IC engines aren't really in balance at any rpm, but are usually better balanced at their design rpms. Run them slow and they sometimes are worse than expected. They also are shaking a lot more mass of their own than the frame was designed to deal with.

Spinners really aren't usually the cause, if ever. They really are something that can be ignored.

It is worth a try to simply swap out the prop. Very, very few of them actually read different pitch on the blades. Very few, and less nowadays with better mfg methods, but it could happen.

I always balance the spinner backplate and front cone together. I scribe a mark on the side of the backplate on to the front cone so they can be reassembled in the same relative position after a prop change.

Thank you. We will do that and see the difference. Cheers

David

Run the engine without the spinner. That will let you know if the spinner is the problem

How do you do it?

I use the Top Flite magnetic prop balancer http://www3.towerhobbies.com/cgi-bin...?&I=LXHY61&P=0. Assemble the backplate and front cone, scribe a mark across the side of the backplate onto the front cone, and slide the whole assembly on to the shaft of the balancer keeping the scribe marks aligned. Balance by brushing a small amount of nail polish on the back of the backplate on the light side. After balancing, install the backplate on the engine, install the prop (balanced separately), install front cone by aligning the scribe marks on the backplate and front cone. Hope this helps.

David:

Check that the propeller is rotating on a plane perpendicular to the engine shaft.
Both tips should touch a fixed gauge located at the tips' arc the same.

If not, the hole of the propeller is not perpendicular to the blades, or the shaft of your engine is bent.

Are you sure your balancer is OK?

Do not fly with high vibrations, that will destroy your model.

Regards!

Thank you, Rufcut.

However, I understand that a plastic cone without a front hole cannot be mounted on the balancer, and that only the back plate can be balanced.

Regards!