Repair lathe motor?

I should have made a sketch when I was looking at it (By the way, my bore scope sucks!) but here's a rough drawing of what I saw under that nice little cover:



I could only see the top side, of course, so I can't say what else is going on in there.

-Ron
 
Yup. That's a universal, all right. Does it look like there is any kind of rotational adjustment in the brush arrangement? Some large frame brush motors were 'tunable' at one time - I think that's how some were reversed.
 
A series wound motor is a horse of an entirely different complexion.

First: bummer - it's a natural for a speed control setup, just like a DC motor (which it is).
Second: maybe it'll be easy. Bad brushes and commutator would do what you're seeing.
Third: maybe it'll be very hard. I have no clue how common brushes are.

I'll go do some looking.

It would be GREAT if you could refurb it, as you'd get the possibility of variable speed control easily.
 
Yup. That's a universal, all right. Does it look like there is any kind of rotational adjustment in the brush arrangement? Some large frame brush motors were 'tunable' at one time - I think that's how some were reversed.

I couldn't really tell. The way my setup is it's a little difficult to get in at that area. I'll have to remove the lathe's switch in order to get a bit closer.

Hah! I ran the model number through Google. I got 10 hits, all originating from HM. :lmao: There's not much info on that motor on the net.


According to the plate, it is 110 Volt only. The fact that there are four leads coming out to the JB shows that it is likely reversible.

I couldn't find much on it either. Not sure how it relates to the internal wiring but if you look at the motor plate there is a line on there that states "ELECT. REV."



-Ron
 
I couldn't find much on it either. Not sure how it relates to the internal wiring but if you look at the motor plate there is a line on there that states "ELECT. REV."
That means "electrically reversable", which is is. Reversing the connections of either of the two series windings while leaving the other one alone reverses the rotation direction.

I did a quick scan through ebay and failed to turn up even one likely suspect.
 
I couldn't open the manual, but the front page mentions a "brush lifting" motor. Fascinating. The commutator is only in play during start-up. If this is what you have, you should see some type of centrifugal mechanism connected to the brushes that will lift them at speed.

Just for reference, I wouldn't advise using a series motor (which R.G. mentioned) in any application other than direct connection. They have the strongest torque of any brush motor, but, if the output becomes broken i.e., a belt comes off), they will "accelerate to destruction".
 
I believe that is an RI (repulsion start induction run motor) not a universal. The link below is
for a Wagner Electric Manual for their RI motors which may be of some help.


http://www.vintagemachinery.org/pubs/detail.aspx?id=3918

Very interesting. I have some reading to do tonight.

Thanks much.

I couldn't open the manual, but the front page mentions a "brush lifting" motor. Fascinating. The commutator is only in play during start-up. If this is what you have, you should see some type of centrifugal mechanism connected to the brushes that will lift them at speed.

Just for reference, I wouldn't advise using a series motor (which R.G. mentioned) in any application other than direct connection. They have the strongest torque of any brush motor, but, if the output becomes broken i.e., a belt comes off), they will "accelerate to destruction".

Got it! example: "runaway diesel" - not good. It makes sense, now that you mention it, with no load there is nothing to limit the acceleration 'til things get exciting and parts start whizzing past your nose. Oh, and try downloading it from this link: http://68.227.91.247/machines/WagnerRepStartInd.pdf It's off my server and I saved it in a slightly different way. Hopefully you can open it.

Thanks Hawkeye

-Ron
 
Ron
I was gone over the weekend and followed up this morning on the progress. Since this is a wound rotor motor it's even better if it's not toast. With a wound rotor the commutator typically has segments on it with mica separating each segment from the next. As the brush's wear down they also wear into the commutator section. The copper/brass section wears down quicker than the mica does causing the mica to lift the brush's as they pass from segment to segment. I have attached a crude attempt at a drawing showing this(i was laughed out of art class in high school. They let me go to shop class instead!) This can be turned down on a latheto flatten it back out, but you need a tiny slot cutter to cut the mica down between segments(only a few thou). Brush's should be available at a motor shop locally. If not I have some yet from back when. PM me and I will give you my address to send me an old one to match up. In the mean time try to find a used motor for a backup and then fix this one if you can. You can use your lathe to do it. The only hard part is getting the Mics cut down. A dremel with a slotting cutter mounted to your tool post somehow should do it fine. Since your an EE this will all make sense to you. Didn't mean to be so basic in my first reply. There's lot's of other good sources of info in the posts since my first reply.
 

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I like your drawing Kevin, has kind of a "Salvador Dali" feel to it. ;)

It seems counter intuitive that the mica would wear less than the copper but what you say makes perfect sense. Before I go tearing apart this motor though, I am thinking that I need to get a better handle on exactly what type of motor I'm dealing with and it's operation. It may seem a bit odd or overly cautious but this strikes me as opening up a "can o' worms" and it's my nature to try and handle a job as efficiently (least work :)) as possible. I'd hate to buy a cheap, used motor as a temp with the plan to rebuild the original then "hit a wall" on the rebuild for some reason. I'd then have to buy a "good" motor to replace the crappy one (again, it's my nature :rolleyes:) and be left with an extra crappy motor as well as a pile of parts that used to be an old motor. Or something along those lines.

That's a great offer on the "brushes" and I may end up taking you up on that but I'm going to do a little more research before I reach that point.

Thanks again,

-Ron
 
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