4 pole conversion? - RC-Monster Forums

**4 pole conversion? -** 05.11.2011, 03:40 AM

I was wandering, if I took an old CM36 motor (4600KV for instance) and replace the rotor with a 4 pole one from the new 1406 motors, will the motor run ok?

Will it have characteristics similar to the CM36? The 1406? Something in between?

Avner.

DrKnow65 · 05.11.2011, 09:11 AM

I think they are two different animals in that the 4 pole motors are also slotted where as the 2 poles are not.

Would it spin up? Not sure, but I suspect not very efficiently if at all.

05.15.2011, 03:25 AM

Patrick,
can you please comment?

Thanks,
Avner.

suicideneil · 05.15.2011, 09:37 PM

They are completely different motors once you get inside the can, I doubt the rotors are the same diameter or length & the windings/ stator are totally different; it would be like trying to convert a 2 stroke engine into a 4 stroke simply by changing the piston...

scarletboa · 05.15.2011, 09:54 PM

Quote:

Originally Posted by suicideneil

it would be like trying to convert a 2 stroke engine into a 4 stroke simply by changing the piston...

That is a pretty damn good comparison. That pretty much explains it. Better than my comparison.

It's like trying to use a SD card in place of a compact flash card.

03:54 AM

Thanks for the input everybody.

I see what you are saying, but I'm not sure they are all that different from one another. If they were, you wouldn't have been able to run both 4 pole and 2 pole motors with the same ESC without even changing any setting.

That's why I'm looking for input from someone at Castle (or someone who tried it).

Avner.

suicideneil · 05:54 PM

Why would you need to change any settings?

The only difference so far as the esc is concerned is that it 'sees' the 4 pole motor as spinning twice as fast due to the extra 2 poles on the rotor, so the total rpm limit you can achieve with 4 pole motors is half that which you can achieve with a 2 pole motor.

Same as a 2 stroke engine vs 4 stroke again; both engines of a similar size will move your motorbike just as well, but the 4 stroke will produce more torque and make a nicer rumble when you open it up, vs the 2 stroke which sounds like a bee in a tin...

You need to look at some pictures of the insides of a 2 pole & 4 pole motor of the same size to appreciate the physical differences ( and understand why you cant swap rotors ), but they still work in the same way when powered by a suitable esc.

Have a gander at this:

4 pole rotor & slotted stator

2 pole slotless stator

The rotor on a 2 pole motor is usually a solid long, round magnet with the shaft running through it. The rotor on a 4 pole is made of 4 separate magnets fixed around the shaft & wrapped in kevlar or carbonfibre usually- the stator is designed to work with a certain type of rotor so changing it could cause it to not work properly, or not work at all.

2 pole

4 pole

By all means try it though, just make a video so we can all watch what happens....

05.17.2011, 05:05 AM

Quote:

Originally Posted by suicideneil

Why would you need to change any settings?

The only difference so far as the esc is concerned is that it 'sees' the 4 pole motor as spinning twice as fast due to the extra 2 poles on the rotor, so the total rpm limit you can achieve with 4 pole motors is half that which you can achieve with a 2 pole motor.

That is exactly why I think that it is possible that if a 4 pole rotor is placed in a 2 pole can it will run (with the ESC switching twice as fast).

Same as a 2 stroke engine vs 4 stroke again; both engines of a similar size will move your motorbike just as well, but the 4 stroke will produce more torque and make a nicer rumble when you open it up, vs the 2 stroke which sounds like a bee in a tin...

I think the analogy is right from the performance point of view but wrong from the design point of view. 2 strokes use ports and 4 strokes use valves and camshafts while 2 and 4 pole motors both use rotors and stators.

You need to look at some pictures of the insides of a 2 pole & 4 pole motor of the same size to appreciate the physical differences ( and understand why you cant swap rotors ), but they still work in the same way when powered by a suitable esc.

Have a gander at this:

.
.
.

The rotor on a 2 pole motor is usually a solid long, round magnet with the shaft running through it. The rotor on a 4 pole is made of 4 separate magnets fixed around the shaft & wrapped in kevlar or carbonfibre usually- the stator is designed to work with a certain type of rotor so changing it could cause it to not work properly, or not work at all.
.
.
.

I have opened many brushless motors including the Castle 1/10 2 and 4 pole motors and even though I haven't made any measurements at the time, the rotor shape and dimensions look very similar if not identical.

By all means try it though, just make a video so we can all watch what happens....

I have 2 CM36 4600KV that are candidates for this conversion. They are the older design with the end-bell glued on and I really don't like opening them.
I don't even think that 4 pole rotors are available to buy as a rebuild kit right now, so even if it works I won't be able to run the converted motor without sidelining one of my 4 poles.

These are the reasons I was hoping to get some input from Patrick and instead of going ahead and trying it.

Avner.

Pdelcast · 05.17.2011, 12:09 PM

Don't do it, it won't work.

You'll just end up smoking the ESC.

Wrong winding type for a 4-pole...

BrianG · 05.17.2011, 01:02 PM

And there you go; word straight from the big cheese at CC...

DrKnow65 · 05.17.2011, 01:27 PM

But what if I just dive slowly and keep an eye on temps?!??!

Kidding of course, just wanted to beat any noobs to it :-)

suicideneil · 05.18.2011, 10:36 AM

Sometimes it's hard to articulate why somethings just wont work or are a bad idea, but if people say 'don't do it', it's generally just a good idea to listen- especially on a forum known as The Encyclopaedia Brushless...

lutach · 05.19.2011, 12:45 AM

Koford seems to wind their 4-pole slotless motors the same way the R/C slotless 2-pole motors are wound.

Pdelcast · 05.24.2011, 05:34 PM

Quote:

Originally Posted by lutach

Koford seems to wind their 4-pole slotless motors the same way the R/C slotless 2-pole motors are wound.

Not the same ...

To do a four pole winding, you need either a 6 slot salient pole winding or a 12 slot skip-2 winding.

To do a two pole winding, you need either a 3 slot salient pole, or a 6 slot skip-2 winding.

There are other winding possibilities, but you can't take a four pole winding and just throw a 2 pole rotor into it, or vice-versa.