RC-Monster Forums - 4 pole conversion?

RC-Monster Forums (https://www.rc-monster.com/forum/index.php)

- Castle Creations (https://www.rc-monster.com/forum/forumdisplay.php?f=34)

- - 4 pole conversion? (https://www.rc-monster.com/forum/showthread.php?t=29986)

4 pole conversion?

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.

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.

Patrick,
can you please comment?

Thanks,
Avner.

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...

Quote:

Originally Posted by suicideneil (Post 406646)

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.

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.

Quote:

Originally Posted by suicideneil (Post 406729)

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.

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

You'll just end up smoking the ESC.

Wrong winding type for a 4-pole...

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

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

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

http://joerob.com/wp-content/uploads...-so1.jpg?w=292

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...

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

Quote:

Originally Posted by lutach (Post 406909)

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.