View Full Version : Rewire an outrunner motor?

03-19-2012, 07:28 AM
:) Is it hard to take apart, and rewire an outrunner motor's armature? ???? How do you identify the correct wire size, :concern: and where do you purchase new wire? ::o Is difficult to do? :eek::)

03-19-2012, 06:47 PM
I just did my first re-wind, it worked out well in the end and the motor is performing like a champ but it isn't the easiest thing in the world. Stripping the motor down is not straightforward because getting the stator of the stator holder is quite a challenge. They are usually glued on so you need to use heat and considerable force (but not too much force) to get the stator off. Getting the old winding wire off can also be a challenge as many manufacturers seal the winding with epoxy. Again heat is often the answer to soften the epoxy.

Once you have the motor stripped and clean then re-winding is easy enough once you know how but it does take practice. I had a few abortive efforts and three completed winds that before i got the correct kv and a quality of winding that I was happy with. You also need to be confident with a soldering iron and have a good powerful iron in order to solder the phase wires together and solder the pig-tails on (the pig-tails are the wires that come out of the motor).

Working out the wire size is an art form in itself. Original manufacturers winding usually uses very fine multi-strand wire but hand wound motors usually use heavier gauge single strand winding. Best bet is to find someone who has wound a similar motor. Wire diameter depends on the stator dimensions and the number of turns you intend to wind, also on the winding pattern you chose as different types of winding (star, delta, DLRK, half parallell etc) all influence how many turns you need to achieve your desired kv.

I ended up buying 6 different wire diameters (try eBay) before I got the one that fully packed the stator with the exact number of turns I needed for my desired kv. I was looking for a 750kv motor, my first successful wind as 415kv, my next effort was 810kv and third time lucky I hit 750 on the nose.

It is very satisfying to wind your own though, and the motor I got at the end of the day is a powerhouse, so I'm very happy:D


03-19-2012, 07:37 PM
:) Is it hard to take apart, and rewire an outrunner motor's armature? ???? How do you identify the correct wire size, :concern: and where do you purchase new wire? ::o Is difficult to do? :eek::)

I've wound and rewound a number of brush and brushless motors. FYI, it's a lot of work, and there are pitfalls. One of the pitfalls is the varnish insulation on the magnet wire. When you make the sharp bends around the stator, that insulation can crack, leading to potential shorted turns when you're all done. If that happens, you've got to strip off all the wire and start over. This is one reason the commercial brushless motors use multiple strands with smaller diameter (more flexible) wire for each winding.

Before retiring the shop where I worked had magnet wire in sizes from #38 to #1/0. They bought this stuff by 100 pound plus spools.

One very good source of information and magnet wire and similar materials is www.gobrushless.com (http://www.gobrushless.com) a place that sells brushless motor kits. It will cost more to buy a motor kit than to actually buy one ready to go. I built up six of the Gobrushless motors, with power ratings on the order of 150 Watts. However they've been put on the shelf for much more powerful Hacker and similar type motors.

Take a look: