Perm Mag DC motor rewinding

[zkling]

Short and sweet, anyone have experience rewinding the armature of a fractional hp PM DC motor? Confirmed my suspicions of a shorted winding. It has a non soldered commutator. Is this just a time consuming, labor intensive process or does it require a lot of special machines and know how?

P.S. Mods if you feel this would be better in the Electrical sub forum, please move it as you see fit.

 

[A_Pmech]

Let's see some photos.

 

[fufu83]

Can be done, by hand will take time. As a kid we did slot car motors. First did you check to see if the windings are shorted ? If so you need to count each pole as you unwind them ,keep track of number of turns. Then start with new wire,need to keep tight as you wind,and keep a eye on how you overlap,one nick and you start over. Look up rewinds of slot car motors should give you some info.

 

[zkling]

Let's see some photos.

Was hoping you'd chime in. I'll get some shots this evening. The windings and stack have no signs of issues, just two slightly arced com bars 180°, which have ~1/2 the resistance of all the other windings. I understand the how it goes together, just not real confident in the rewinding process. I've done a few AC motors being able to create the windings independent of the stator stack, but those were much simpler. The whole passing the wire through each slot and then back around seemed like it would be daunting. Which is kinda why I figured the quote to rewind was so high.

Can be done, by hand will take time. As a kid we did slot car motors. First did you check to see if the windings are shorted ? If so you need to count each pole as you unwind them ,keep track of number of turns. Then start with new wire,need to keep tight as you wind,and keep a eye on how you overlap,one nick and you start over. Look up rewinds of slot car motors should give you some info.

Yep, unfortunately I'm 100% sure it has at least one shorted winding. It has magnetic resistance, lower ohms and does not pass a growler test. Yes I'm familiar with slot car, or mostly model train motors. Those are much simpler with a fraction of the poles and much thinner, easier to thread wire. Again I understand the idea, workings and how to, was just wondering about practicality if someone has done this before and can shed some light on what I am up against.

 

[Alan Douglas]

In my 3 summers in a motor shop I think we did one armature rewind; way too expensive even back then (it was a ventilator motor on a Martha's Vineyard ferry that had formerly been a Navy vessel). However I don't know of any reason you couldn't do it by hand.

 

[zkling]

Sorry for the delay in pics, I forgot I put it back together and loathed pulling it apart again. Anyways... what say the experienced, doable for a not so smart DIYer?

 

[A_Pmech]

You don't have to pass the wire thru the slots. Just like a stator, the slots are packed with wood shims. They'll come out when you strip it.

 

[zkling]

You don't have to pass the wire thru the slots. Just like a stator, the slots are packed with wood shims. They'll come out when you strip it.

Hum, didn't look like there was going to be enough clearance. : That is good news though, now just to dig up my winding jig. Any other words of wisdom? I made a chart of which com bar goes to the specific slot. When I talked to a small motor shop for a quote (mid to high $200's), they made specific mention of the stamped and not soldered commutator contributing to a large portion of the cost, something about ~$100 by itself. I've skimmed coms before on the lathe, but not sure about an entire replacement.

If it helps, it is a 3/4hp baldor. I should have thrown a 6" scale in for reference.