How do you balance a spinner?

[David Davis]

I know how to balance a propeller but how do you balance a spinner?

[Steve Hargreaves - Moderator]

Depends on the spinner......if it has a hole through the tip (like a typical aluminium IC spinner) I mount it onto my magnetic prop balancer (I do the backplate & the "nose" seperately) using a mandrel through it....I then add bits of gaffer tape to the inside surface to balance it.

If the tip has no hole then I don't see how you could balance it accurately......

[IanR]

The 2 brothers website describes how to balance a spinner which has a backing plate but which does not have a hole through the tip, using a Dubro prop balancer.

**LINK**

The second video describes spinner balancing.

Ian

[Alwyn Gee]

Hi Folks

I have just done this in the last couple of days whilst repairing my crashed E-Flite Hurricane. The original plastic spinner has the hole in the cone as many of the alloy IC ones do but the one I was fitting was just the usual electric type with the two screws at the side to secure it. I use the Great Planes Power Point Precision Balancer to balance my props and thought I'd have a go at the spinner. I fitted the backplate, one bush tapered side & one bush flat side onto the mandrel close to one end so that the long side of the mandrel faced the spinner cone. I then pushed the spinner onto the backplate and secured it with the screws so that the point of the mandrel was right into the point of the spinnere cone. In this way the magnets which support the mandrel in the balancer are pwerful enough to support this setup through the plastic cone.

You can then carry out the balancing by whatever method you choose, either removing material from the heavy point or adding sticky tape to the light side as described in an earlier post. In my case I trimmed the prop ports as these had been adjusted to accomodate the prop and were obviously uneven.

This was all done on a two and a half inch dia spinner.

Hope this helps.

Alwyn

[Alwyn Gee]

Just realised I did not make it clear above that I balanced the backplate first before addng the spinner cone. It's then a good idea to mark both parts so that they are assembled the same way each time.

Alwyn

[john melia 1]

Why do we need prop/spinner balancers these days ? Surely with todays technology decent retail props will be balanced ! Just wondering how many people have actually bought an out of balance prop/spinner , and is it a reasonably common occurence .

[Biggles' Elder Brother - Moderator]

John, I suggest that you use the search box to answer your question - so avoiding going back again over a debate that has been "done to death" on here several times before!

BEB

[Steve Hargreaves - Moderator]

Its as common as a very common thing John...I can't remember when I bought a prop that was balanced. They ain't much out but they are out...

[Alwyn Gee]

Hi John

I purchased a well known make of propellor as recently as Thursday and it clearly states on the packet "Balance before use". Spinners are probably less critical as they are much nearer to the centre of rotation but the the further any imbalance is from the hub the greater will be the effect.

Believe me it makes a difference, some time back in my early stages of this hobby one of my electric models used to make as much noise as some IC models until I balanced the prop etc.

Alwyn

[john melia 1]

Wow I honestly didnt know that , I just buy em and stick em on , never seems to be any vibration issue , but maybe a balancer will be going on my things to get list

[Shaunie]

Hi John,

Buy a balancer and balance your props and you'll probably be amazed you didn't do it before!

I put cameras on one of my electric planes and got the "wobblies" on the resulting footage, so out came the balancer. After balancing the prop, adjusting the run-out of the motor and finally making small adjustments in the relationship between the motor and the prop the image is almost entirely wobble free. The thing is that the motor now sounds almost turbine smooth.

To listen to it before you wouldn't really have thought anything was out of balance but listening afterwards it sounds so much better.

Just put together a Wot4 foam-e I got at the Southern Model show yesterday, yep that prop'll be going on the balancer tomorrow.

Shaunie.

[David Davis]

The reason for putting up the original post was because I crashed the club i/c trainer, a VMAR Appache II a few weeks ago and whiped off the nose. It had been given to the club by someone who lives in France and it was fitted with an MDS 58 engine which despite the attentions of many of us including a retired Rolls Royce engineer who even altered the taper of the needle on his lathe, would never run properly. Sometimes it would tick over and run at medium speeds but cut out at full throttle, sometimes it would run at mid and high speeds but not tick over. Those of us old enough to remember MDS engines will know what I'm talking about!

As the Apache is a 40 sized trainer, I donated my Thunder Tiger GP 42 which was looking for a home and the model remained suspended from the club house for several years. No-one had ever seen it fly so I took it home, charged the battery and flew it one Thursday afternoon.In the air I found that I was having to give the model full down trim and hold in some down elevator in order to get it to fly straight and level and while I was able to fly it in this way, landing it was a different propostion. I had neglected to check the centre of gravity and as the GP 42 is a much lighter engine than the MDS, the model was tail heavy and I made a complete horlicks of the landing. Lesson learned I hope.

Having repaired the model and having moved the receiver battery further forward and having added lead behind the firewall, I carried out a number of checking flights in order to adust the control surfaces so that the trims were at neutral on the transmitter. It was while carrying out these flights that I noticed that the engine seemed to vibrate more than I recall. I balanced the propeller but it still seemed a little rough at some speeds. It is fitted with a cheap spinner which has been hacked about. I'll balance the back plate when I get a minute.

[Glyn R]

I find APC props generally are balanced out of the box. I recently bought 4 wooden props from Hobbyking which were all Ok except one neede a small touch of laqcuer to a blade. I have most trouble with Master Airscrew which do seem to need quite a lot of balance correction. I haven't bothered with spinners maybe I will have a go and surprise myself.

[Colin Leighfield]

I thought that I would resurrect this thread. For me balancing a prop is a no-brainer, most of them are out to some degree and the difference it makes is substantial. However, I still don't have a good solution to balancing spinners that don't have a hole at the tip of the cone. Does anybody else?

It's been highlighted for me with the search for suitable commercial spinners for the Seafang, which features a spinner that has a length greater than the diameter. The commercial ones tried so far are a mile out. Fortunately I have one that is suitable and I'm using it, but it would be nice to find some alternatives. If I could balance the ones bought on Ebay, that otherwise look fine, it would be OK.

Clearly there is a case here for 3D printing, assuming that the plastics used are resistant to bursting at high rpm. I'm thinking about this. Also assuming of course that the wall thicknesses are sufficiently consistent to ensure good balance in the first place!

From the previous contributions to this thread, clearly I'm not the only one to scratch my head over this one, but does anybody have fresh thoughts on the subject?

[ASH.]

Colin,

I agree, balancing a prop is a no-brainer. I do that easily with a small hand held GP one.

Though I have never attempted to balance an alloy spinner I would like to in my future installations. The trick is I suppose in marking-out and cutting for the blade roots exactly so they're symmetrical. And then? It's funny this subject is one that's always skipped over.

[Colin Leighfield]

Hi Ash.

I think you are right with the aluminium ones, as long as you keep the cut-outs identical there shouldn't be much of an issue. They are usually made by spinning from an aluminium blank and that pretty much ensures that they will be true and balanced. The one I am using on the Seafang now is of that type.

Problems arise with moulded plastic spinners. It is surprising and probably isn't so obvious with i/c motors, but it is with smoother running electric. The two recently purchased appear to be well made from what looks like a thin carbon-fibre lamination, with nice turned aluminium back-plates. The back-plates are perfectly balanced. However, when the spinners are assembled on the plane there is unacceptable vibration with both. The prop is balanced, so are the back-plates, so it has to be the moulded spinners themselves. I don't have a good answer to the problem.

Edited By Colin Leighfield on 17/03/2016 10:02:48