Bent Motor Shaft ???

[Nigel Heather]

I managed to put my AcroWot Foam-E into the ground a few days ago.

 

I thought it had gone nose in and I expected to find it in pieces but it wasn't anywhere near as I thought - didn't even break the prop - landing gear seemed to have taken the brunt of the impact, it got ripped off and bent. There were a few cracks in the fuselage but I have repaired all of those, straightened the gear and reattached it.  From a short distance it doesn't look like there was ever a crash.

 

Was planning to take it out to day and I noticed that there is a very slight bend in the motor shaft - you can't see it by the eye but as the motor turns you can see the spinner wobble a little.

 

So questions?

 

• Is a slight bend in the motor shaft an issue - the motor turns fine, produces plenty of thrust - should I just fly with it, this is just a beater I don't expect precision and finesse from it.
• Or should I replace the motor - maybe get the upgraded version.

 

Now I'm not against getting a replacement motor but I have some more questions if I do go down that road

 

• The replacement motors have a plain shaft but my AcroWot has a threaded prop driver - how do you remove and fit those.
• Would I have to remove the motor with prop driver attached to be able to remove the prop driver - this would be a little difficult as the prop driver partly obscures the fixing screws

 

I've also seen that you can buy new motor spindles for £5 - obviously I would have the same question about the prop driver but how easy is it to replace a motor spindle?

 

Appreciate any advice you can offer

 

Cheers,

 

Nigel

 

 

Edited April 18, 2022 by Nigel Heather

[Geoff S]

I replaced the motor shaft on my Acrowot Foamie quite a few years ago (the reason is almost too embarrassing to describe) and I don't remember its being a problem.  I can't recall how the prop driver fitted but I assume it just clamps onto the plain shaft like a collet.  I can't recall seeing a threaded motor shaft on any brushless motor.  The only threaded part of a prop driver is the bit where the prop fits and is on either the collet attachment or on a fitting that bolts onto the rotating case.

 

In your case, I'd swap the shaft rather than fly it with a bent one with the resulting vibration.

[Wihtgar]

I was given a wot 4 foam e which had obviously gone straight in looking at the damage on the front end of it. There was also a slight wobble on the end of the prop shaft when I ran up the motor so I replaced the prop driver (collet style which slid off) and the motor shaft. I then ran up the motor again only to find there was still a wobble on the end on the shaft which I put down to the prop adaptor not being concentric at the prop clamping nut end but Ok at the motor end of the adaptor as it looked as if it was running true at the motor end.

[Shaun Walsh]

The prop driver is usually made of softer metal than the motor shaft so it may only be necessary to fit a new prop driver. 

If the prop driver is very tight on the shaft it may be necessary to use a puller to remove the retaining collar and then prise or tap it off. 

[Nigel Heather]

I've been playing around with it since I posted and have manged to pull the prop driver off - it is a collet type and it came off much easier than I was expecting, thought I would need some type of puller.

 

Now the dilemma - is it the prop adapter or the shaft that is bent - hard to tell because the bend is very minor.

 

Cheers,

 

Nigel

[Outrunner]

Nigel, if you run the motor without the prop adaptor you will see if the shaft is bent.

 

Why do you have two threads on the same subject?

 

Phil

[Nigel Heather]

3 hours ago, Outrunner said:

Nigel, if you run the motor without the prop adaptor you will see if the shaft is bent.

 

Why do you have two threads on the same subject?

 

Phil

 

I considered them two different questions - one about flying, is it okay the fly with a slightly bent motor shaft - and the other about motors, how do you remove the prop driver.

 

I have managed to remove the prop driver and have run the motor without it - I don't think the shaft is bent but then again with such a slight bend I'm not sure I would be anu to tell. I do suspect that it is the prop driver that is bent, as others have said it is a softer metal - so I've ordered a new one.

 

Cheers,

 

Nigel

 

 

[Outrunner]

You should be able see even a slight bend with the motor running.

As already mentioned the soft prop adapter is more likely to bend than the motor shaft.

I hope you get it sorted soon.

[Nigel Heather]

1 hour ago, Outrunner said:

You should be able see even a slight bend with the motor running.

As already mentioned the soft prop adapter is more likely to bend than the motor shaft.

I hope you get it sorted soon.

Thanks, yes I agree.  I’ve ordered a new prop adaptor anyway as like you I am 99% sure that is where the bend will be.  I’ve also held my finger against the motor shaft while it is turning - feels smooth, I assume it would be like a tingling massage if it were bent.

 

I’ll update on Friday as I should have the spare part by then.

 

Cheers,

 

Nigel