Beginner wind project - questions

[frepdx]

Hi group. I'd like to use this old fan motor for my first wind project - a 12V charger. The stator has sixteen slots. Any suggestions?

1. What type of windings are recommended - single phase? multi phase?
   
2. can I turn the rotor down and mount the permanent magnets, or will the aluminum conductors cause induction problems? (the magnet on the rotor is 1/2x1/4x1/16 for scale)
   
3. any suggestions on the blades? I'd like to spend some time and make nice ones for the learning experience? something like this.
   
   

thanks

[Janne]

Hi,

The motor is quite small, but it should make for a nice learning experience. The number of slots (16) restricts your windings to a single phase configuration, but i would not worry about it too much as it will be a small machine.

The aluminum bars in the rotor won't harm you much. You will need to skew the magnets in order to reduce the cogging force on the rotor once magnets are installed (cogging=magnets trying to position themselves to the iron in the stator)

[ghurd]

It is a big job to change the windings in something that small.  There is not enough room to work.

There is not much room for much magnet volume, so it will need a lot of turns.

Something larger would be easier to rewind.

I would not bother trying to rewind it.

I would turn the rotor down to hold those magnets 2 deep, and a bit more.  Each pair would be "one magnet".

Then I would mount 8 magnets One Deep: 2 N, space, 2 S, space, 2 N, space 2 S, space.

Then after the epoxy is cured, add the second layer. (easier that way)

Total magnet count is 16.

The first layer being close to each other will not want to lay flat, so it takes a little extra space to make up for any tilt they do.

One pair of wires will make some power.  Not much.

The others will probably not make anything worth trying to get. But if they do, the common connections (in the paper under the zip ties) will need to be separated.  I would separate them for testing anyway.

I expect it will end up high voltage and low current.  Low cut-in RPM (relative to a suitable blade size).  May be better suited to a low TSR 5 blade prop.

Don't over-think it too much and it will be a fun first project.

G-

[frepdx]

Thanks for the ideas.

It is a big job to change the windings in something that small.  There is not enough room to work.

How about making a single large coil and wave-winding it all at once. Is that doable?

I'd like make a single-tooth test coil, take some measurements and design the full coil and blades to match. But now that you mention it those slots are pretty small.

[ghurd]

A wave winding is probably the worst idea...

The wire would lay in at an angle, with wasted space.  Might get around that by placing a dowel rod in the adjacent slots to hold each wind down toward the bottom of the slot?

The core will need turned a bit after every slot or 2, and it is easier to work on the core if it is held still in a clamp.  That would be a lot of clamping and re-clamping.

I think it would take more wire, meaning more resistance.

As the wire is pushed through the center for the next turn, the last turn tries to escape.

It is a 3 handed operation in a space for less than 1 hand.

People with more patience than me have done it.  I find it quite frustrating to get even a few layers in for a test winding.

With the small magnets and large number of turns required (100s), I do not believe a single test winding is sufficient to estimate the final number of turns.

Hey.  It is your baby!  I'm just going from my personal experiences, and my low tolerance for frustration.

I would fit it with magnets and test the factory coils first.  It will work (which always feels good), and your 1st project is a success.  

Then try rewinding it...

G-