In article ,
micky wrote:

I have 3 or more choices.

Fix the fan:
1) Rewind the motor myself. The motor shop will do it for me for
200 but I'd much rather do it myself. I'll do the winding while I'm
watching TV. Magnet wire runs between $6 and 11 including shipping.

I went to 3 shops to buy a new motor, but failing that, I asked for
advice on rebuilding: The first motor shop said it used 31 gauge.
The second shop is closing and he couldn't find his wire gauge, but
his micrometer said it was 0.010 inches, which is 30 gauge. And the
third shop said it used 29 gauge. The first and third shops
didn't tell me if they used a guage or a micrometer.

What gauge should I use, 29, 30, 31, or should I take it to more
places to find out their opinion? I also have my own micrometer
around here. It's cheap, but it says exactly zero when closed and one
inch when open afaict one inch. Does that mean it will be accurate to
1/1000 of an inch?

(29 guage is 0.0113 inches; 30 gauge is 0.010 inches: and 31 guage is
0.0893 inches.)



You apparently have internet access, so you have access to at least
100,000 motors that your 3 local shops don't stock. You may be able to
identify the frame size, mounting style, RPM, HP, and any other relevant
info, and buy a new motor.

Regarding magnet wire, I'm somewhat familiar with it because I have
wound transformers, guitar pickups, and various small coils in a
production environment.

Your motor is not wound with bare copper, obviously. Insulation adds
thickness. That complicates reverse engineering.

There are several different materials used for insulation these days,
and they may be applied in different thicknesses. Likely these materials
are different than those used when your fan was made.

Wire gauge is related to some "nominal" diameter, a chart of which you
obviously have. Actual varies from nominal. I specify "min to nom"
(minimum to nominal) when I buy 42 AWG wire for guitar pickups, because
I need to cram thousands of turns into a small space. The supplier goes
out into the warehouse with a toolroom micrometer and looks for spools
that are running on the low side of nominal for me.

So, with an unknown material at an unknown thickness used for
insulation, no way to know how close the wire you actually have is to
the nominal diameter for the specified gauge, and an inexpensive
micrometer, I'll confirm that you're in somewhat of a pickle as far as
wire gauge identification.

All that said, if you've got the physical room for it, I'd go with the
29. Bigger is better, right? Getting the right number of turns on there
is more important than DC resistance anyway, so focus on counting well.