Nov 12, 2003, 06:59 PM
For Sale-everything over 250 g

7.5mm brushless motor

This is my first BLDC motor with my own windings in it. I used large wire to prove the concept, that's why it's 7.5mm. Next try will come out closer to 6mm.
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Nov 12, 2003, 10:36 PM
Master of the Wind
AIR MOVER's Avatar
sweet Brushless where is the third wire?
Nov 12, 2003, 10:53 PM
Registered User
billystiltner's Avatar
How did you wind the coils?

Nov 13, 2003, 05:47 AM
For Sale-everything over 250 g
There are acually all 6 wires coming out the back of this motor so I could run it as Y and Delta.

The winding is done similar to a coreless pager. The coils are put on a piece of tape and then wrapped around a mold. Technically it is a Brushless, Sensorless, Slotless, DC Motor.

Nov 13, 2003, 06:27 AM
Registered User
billystiltner's Avatar
Do you have a diagram of how they are wound?
I would like to rewind some of my broken ones with a different guage wire and different resistance.

Nov 14, 2003, 12:00 AM
Master of the Wind
AIR MOVER's Avatar
sweet so you have them in two bundels of three gotcha man that must have been some tough doing with the wires being so small.. are you going to gear it or DD the motor? what are you going to do about a esc for this?
Nov 14, 2003, 06:00 AM
For Sale-everything over 250 g
Once I worked out the process it was relatively easy. I won't do anything with this one, it is way too hot and was only intended to prove the process. The next couple will be winding development, it may be some time until I have one to try on a plane. ESC I make will be on-off, however the motor will work with commercial BLDC ESCs. For a little more about the ESC I intend to build see Billy's thread on Micro Bushless Controllers.
Nov 14, 2003, 09:31 AM
in persuit of low wing loading
Gordon Johnson's Avatar
It sounds like you are doing good work. I know about working out the process. Keep it up.

Nov 14, 2003, 06:51 PM
For Sale-everything over 250 g
I guess if I "fed" it 3 phase AC at 5 or 6 volts it would run. So it must be an AC motor. Oh well,
back to the drawing board
Nov 14, 2003, 07:22 PM
Sticky Shepherd
Graham Stabler's Avatar
I'm interested in the winding process is sounds like you make a flat coil and then make it form a tube by rolling but that isn't quite the same as a pager is it as that doesn't have a seam or have I got this all wrong and you wind around(and through) a cylinder?

What about French knitting or braiding a winding

Nov 15, 2003, 01:10 AM
Dieselized User
gkamysz's Avatar
Yeah I catch myself calling them DC motors too at times. Funny how they're driven by an amplifier without ground reference from a DC source that messes with our heads so easily
AC motors operate on fixed frequency sine wave voltage sources. This is not the case with our Brushless DC motors.

Nov 15, 2003, 06:31 AM
Crash Master
Gene Bond's Avatar
All motors operate on AC. A commutator is a mechanical inverter, reversing the polarity of the windings as it switches.

You are all correct.

Don't feel bad, we have the same debate in the industrial world. Brushless DC = Permanent Magnet AC...
Nov 15, 2003, 05:11 PM
For Sale-everything over 250 g

Winding diagram

Here is a very crude drawing of the way I make the windings for my BLDC motors. I believe most coreless pagers are done flat and then rolled around the comutator piece. All the 6 or 7 I took apart had a slight gap or misalighment at one of the termination points.

Each phase contains 2 coils wound in opposite directions. There are 3 phases. The first is highlighted in pink on the sketch. The second is highlighted in yellow. The third is not highlighted.
When wrapped around the mold, the two coils from each phase are 180 degrees apart. Coils can be made in many ways, I wind them on an arbor the appropriate diameter and tie them with thread. The different diameters for the three phases is only for clarity on the diagram.
Nov 15, 2003, 05:26 PM
For Sale-everything over 250 g
Here is a winding and the mold. The mold diameter is suficient to clear a magnet from a coreless pager motor. The pin sticking out the mold is the diameter to press fit the bearings from the same pager motor that gave up the magnet. The winding is normally not removed after taping to the mold but this one is no good.
With the winding taped on the mold back iron must be added. Rings made from a magnetic metal are best, but I don't have any. I have been using sheet metal wrapped around the winding in two layers. I then wrap some thread around the motor for a little extra strength and coat with epoxy.
Cover with shrink tube and let cure.
Nov 15, 2003, 05:32 PM
For Sale-everything over 250 g
After molding with shrink tube removed.

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