Shaft reversal

[Andy J]

Have a Turnigy 3548 which I want to reverse the 5mm shaft so that the shaft is protruding at the opposite end to the wiring. Shaft is currently a tight fit to the rotating part of the motor and will require freeing with a suitable impact driver.

Can a shaft reversal be performed on this motor as don't want to destroy or bend the shaft in the process of removal.

[Dickw]

There is a download on the HobbyKing website that shows a bolt on prop driver if you want to fit the prop at the other end, so it does not appear to be designed for (easy) shaft reversal.

Dick

[Andy48]

That bolt-on prop driver is supplied as standard with the SK3 motors. I always use that in preference to the clamp type prop driver. You can also buy them as spares.

It is designed to be able to remove the shaft, otherwise you would -not be able to use the clamp prop driver.

[Andy J]

Have the bolt on prop driver but can use it as it not compatible with my folding prop spinner.

[Dad_flyer]

I have a 2nd hand unmarked motor of a different type but similar size. I crashed and bent the shaft. I could not make the shaft move to get it out to replace, but someone with a workshop lever press pressed it out easily. I have since had to do it myself on his press to clean out soil after another lawn dart. Hitting it hard enough to move it with a hammer or impact driver I think would have loosened something else or bent something. A press is no impact and is straight.

[Shaun Walsh]

I had a similar problem with a motor installation. I used the bolt on prop adapter with a bit of thread lock on the fitting screws, and then chose a suitable spinner to match the adapter. What size/type of spinner and prop do you currently have, pics are helpful.

 

Edited By Shaun Walsh on 07/05/2020 18:20:03

[Jeffrey Cottrell 2]

Hi Andy

Just had a look at an SK3 in my stock, and noticed a grub screw in the spigot , opposite end to the wiring.

Have you tried loosening that?

probably held in with locking compund, or quick setting cement as I prefer to call it, so might meed a bit of heat to help out.

Once loosened a gentle tap on the shaft should be enough to move it.

Try it and see

Jeff

[Gary Manuel]

I think I can just about see a grub screw in the top photo. Be careful - those grub screws are made out of cheese.

Once grub screw is removed (or drilled out), shaft reversal is fairly straight-forward.

[Andy48]

Posted by Gary Manuel on 07/05/2020 22:18:25:

I think I can just about see a grub screw in the top photo. Be careful - those grub screws are made out of cheese.

Once grub screw is removed (or drilled out), shaft reversal is fairly straight-forward.

There are 2 grub screws on these motors from memory.

Edited By Andy48 on 07/05/2020 22:25:52

[PatMc]

There will be a circlip on the shaft at the wiring end. It's there to keep the bearing in place but also to stop the shaft being moved in the other direction if the bolt on prop driver is used. For the shaft to be reversed it should have a circlip groove near the tip or a collet at both ends as on this version.

BTW avoid moving the shaft by impacting it as it can also loosen of the magnets. When I've reversed shafts I've used a pillar drill with blocks of wood as a press.

[Guest]

i have used a light vice with the motor held in place with blocks suitably holed etc so that shaft can be pushed straight thru when vice closed

[Andy J]

Well have the motor apart and can see that if I reverse the shaft, that the circlip recess will not be in the correct position. Don't think would be an issue as the shaft could be secured by a collet.

Possible option would be to turn down the threaded shaft extension to 5mm which would then allow it to fit to the spinner but suspect the metal would bend at the slightest knock.

[John Emms 1]

Unfortunately, people are going to incredibly frustrated by this post:

I know there have been articles, and it appears some have been successful in doing this, but never attempt to reverse the shaft on an outrunner motor. I would suggest that if someone cannot afford the radial mount set, then they most certainly can't afford to take the risk of wrecking a motor.

A quality motor will have the shaft firmly assembled to the rotor, the whole assembly checked for true, and may be balanced. A quality motor could have this glued together to make sure nothing moves (the forces are incredible).

Reversing the shaft risks damage to the motor, and if it is achieved the rotor could be slightly out of line, reducing motor efficiency, if it runs at all.

It would be fair to say that I have a decent motor collection, but if I did not have a suitable motor, I would simply buy one that was suitable, rather than risk wrecking a motor. I also think it would be fair to say that I know a little bit about electric motors.....

I hope that has not frustrated TOO many readers.

Take care in these days,

John

[FlyinBrian]

Take John's advice, if any one knows about leccy motors it is John.

 

I bought one of the first AXI motors from him in about 2004 - I still have it.

Edited By FlyinBrian on 08/05/2020 12:30:01

[PatMc]

Posted by John Emms 1 on 08/05/2020 09:13:38:

Unfortunately, people are going to incredibly frustrated by this post:

I know there have been articles, and it appears some have been successful in doing this, but never attempt to reverse the shaft on an outrunner motor. I would suggest that if someone cannot afford the radial mount set, then they most certainly can't afford to take the risk of wrecking a motor.

A quality motor will have the shaft firmly assembled to the rotor, the whole assembly checked for true, and may be balanced. A quality motor could have this glued together to make sure nothing moves (the forces are incredible).

Reversing the shaft risks damage to the motor, and if it is achieved the rotor could be slightly out of line, reducing motor efficiency, if it runs at all.

It would be fair to say that I have a decent motor collection, but if I did not have a suitable motor, I would simply buy one that was suitable, rather than risk wrecking a motor. I also think it would be fair to say that I know a little bit about electric motors.....

I hope that has not frustrated TOO many readers.

Take care in these days,

John

I disagree. Some motors are designed for the shaft to have alternative positions. The shaft has the flats & circlip grooves in 2 different places so that the alternative position is easily achieved if it is pushed through after the circlip & grub screw are removed.
Also spare shafts are often available, in fact some motors come with a spare shaft included.

OTOH motors like the one featured in this thread are simply designed to have the shaft in one position.

[Andy J]

Posted by John Emms 1 on 08/05/2020 09:13:38:

Unfortunately, people are going to incredibly frustrated by this post:

I know there have been articles, and it appears some have been successful in doing this, but never attempt to reverse the shaft on an outrunner motor. I would suggest that if someone cannot afford the radial mount set, then they most certainly can't afford to take the risk of wrecking a motor.

A quality motor will have the shaft firmly assembled to the rotor, the whole assembly checked for true, and may be balanced. A quality motor could have this glued together to make sure nothing moves (the forces are incredible).

Reversing the shaft risks damage to the motor, and if it is achieved the rotor could be slightly out of line, reducing motor efficiency, if it runs at all.

It would be fair to say that I have a decent motor collection, but if I did not have a suitable motor, I would simply buy one that was suitable, rather than risk wrecking a motor. I also think it would be fair to say that I know a little bit about electric motors.....

I hope that has not frustrated TOO many readers.

Take care in these days,

John

Obviously you must have been too heavy handed in dismantling motors John as I found the whole process very easy.

Some tips you may wish to use in the future when dealing with cheap motors like Turnigy are as follows:

Motor shaft grub screws must be removed with a good quality Alan key driver. A standard Alan Key will almost always damage these tiny screw inserts and once damaged it is a pain to drill them out.

The prop shaft must be pressed out using a pillar drill as suggested by others. I used a small drill inverted in the chuck as pictured. Refitting the shaft in its new position is easily achieved by hand

Given the circlip on the fixed casing can no longer be used, a collet must be fitted onto the shaft to ensure the rotating casing is not pulled off in flight by the prop thrust. The washer under the circlip must be refitted because the bearing is slightly recessed thus allowing some clearance for the collet.

Locktight should be used on the grub screws particularly on the rear shaft collet as this takes the full force of the prop thrust.

A new flat is required on the shaft for the retention of the rotating cage of the motor located at the front. This is easily achieved by using a bench grinder and touching the shaft to the edge of the wheel. Resulting indent can then be cleaned up with a needle file.

[Keith Berriman]

Was John Emm's the manager of Puffin Models who were agents of a brand of special Brushless Motors ??

[BackinBlack]

Some motors are designed with reversible shafts, some aren't. Simple.

Those with reversible shafts will have alternative circlip grooves and flats. I do not like the bolt on prop adaptor type where commonly the entire thrust is taken solely by the circlip, poor engineering practise. It appears to work OK for small motors , but I will not trust that method for anything over a couple of hundred watts.

Others may disagree, just my take on it being from an engineering background.

Meanwhile Happy building and Happy flying whenever that time comes.

[Martin Harris - Moderator]

Posted by RC Plane Flyer on 09/05/2020 18:50:40:

Was John Emm's the manager of Puffin Models who were agents of a brand of special Brushless Motors ??

John and his wife Sandra owned and ran Puffin Models.  Sadly, they sold the business and I think it has now closed - if my experience of the new service was anything to go by, I'm not terribly surprised.  Customer service under John and Sandra was second to none.

Edited By Martin Harris on 10/05/2020 14:28:34

[Andy J]

Posted by BackinBlack on 10/05/2020 11:05:34:

Some motors are designed with reversible shafts, some aren't. Simple.

Those with reversible shafts will have alternative circlip grooves and flats. I do not like the bolt on prop adaptor type where commonly the entire thrust is taken solely by the circlip, poor engineering practise. It appears to work OK for small motors , but I will not trust that method for anything over a couple of hundred watts.

Others may disagree, just my take on it being from an engineering background.

Meanwhile Happy building and Happy flying whenever that time comes.

This motor did had a circlip plus a collet so belt and braces. Shame I dont own a lathe otherwise I would have cut another recess so have to hope the collet stays in place which it should do as I utilised one of the original flats on the shaft for the grub screw to act on.

Cant see why John was so against shaft reversal though, put perhaps on say an Axi motor things my be more difficult.

[gliggsy]

Swapped and reversed many electric shafts, some bought and others home made. from piano wire, grooved for circlip with dremel and cut off disc, the fact that replacement shafts are sold would indicate to me that it's OK do dismantle and rebuild electric motors, model engineers is what I thought we were!

[John Emms 1]

From memory, the first motors to have the repositionable shaft were the HET motors, but they were not particularly well made IMHO, or particularly efficient, but I believe they set the expectation for reversible shafts.

Ales Pelikán, the owner of Model Motors, glued the shafts into AXi motors (not personally!) to maintain accuracy and efficiency. We bought static display motors that looked perfect, but did not meet the spec for accuracy, and would have been down on efficiency, if they ran at all.

Mr Palická, the AXi designer, moved to HVP (that had been the Czech state ARTF producer), to develop his design ideas, and the product of that were the HVP Roton motors (an outrunner with the shaft supported at both ends in a case). I also saw Mr Palická producing prototypes for an outrunner motor in a spinner, to take a pair of folding blades.

I believe that the culmination of Mr Palická's design work came at MVVS, where the Roton ideas were developed with a move back to motors where all the parts could be replaced (in common with all of his earlier brushed motor designs).

And the point? During engine training at MVVS, I was told, yes, they supply replacement shafts, but the motor may not be so efficient after the shaft has been replaced....

Yes, Puffin Models, and perhaps that level of service coupled with low margins (not peddling low cost motors as premium quality) is the reason why I am back teaching (including the use of hand tools to an accuracy of 0.06mm), and Sandra is now a Qualified Nursing Assistant. For the future? We have outline plans for a move to Houston, TX.

Do take care Y'All

John

[Andy48]

Posted by PatMc on 08/05/2020 23:03:24:

OTOH motors like the one featured in this thread are simply designed to have the shaft in one position.

No they are not. They come with two prop adaptors, one is bolt on, the other is a clamp fitting that can only be attached if the shaft is reversed.

[Dickw]

Posted by Andy48 on 11/05/2020 12:59:48:

Posted by PatMc on 08/05/2020 23:03:24:

OTOH motors like the one featured in this thread are simply designed to have the shaft in one position.

No they are not. They come with two prop adaptors, one is bolt on, the other is a clamp fitting that can only be attached if the shaft is reversed.

Or with the motor turned round and used behind a "firewall" type mount - done that myself a few times.

If you have to grind a flat or a circlip groove yourself I can't see as it has been "designed" to have the shaft reversed.

Dick

[PatMc]

Posted by Andy48 on 11/05/2020 12:59:48:

Posted by PatMc on 08/05/2020 23:03:24:

OTOH motors like the one featured in this thread are simply designed to have the shaft in one position.

No they are not. They come with two prop adaptors, one is bolt on, the other is a clamp fitting that can only be attached if the shaft is reversed.

Oh yes they are.

Either prop adaptor can be used without reversing shaft.
If the shaft is reversed it needs some reworking as described by Andy Joyce because the motor isn't designed to have the shaft reversed.