Tuesday, December 27, 2011

How to Re-wire a Potted Motor, Part 16: Re-attaching the Field Core

Now we’ll begin closing the motor back up. Please orient your motor as shown in the photo above, which is the way we had it in Part 15.

Then note that there will be a potential problem in closing it up, as seen below:

If we’re not careful, the bottom motor lead will block one of the screws that attaches the field core to the rest of the housing.

To prevent this, we insert that screw prior to closing up the motor.

Insert the screw all the way, and tuck the motor lead behind the screw.

Then, as we begin closing the motor, we ensure that wire stays behind the screw.

The tricky part is that we must guide the screw into the screw hole. This may take you a few tries.

Once you feel you’ve got the screw properly seated against the hole, test it with the screwdriver and see if you can tighten it.

If it does not want to easily tighten, STOP and try re-seating it. If you get the screw in at an improper angle, you can strip the threads, which is bad news.

Once you feel the screw going into the hole properly, begin tightening it--but don’t tighten it all the way. Get it up to about the point shown in the photo below, leaving a gap between the core and the housing.

Then we turn to the other screw we need to do on the other side.

Don’t forget this side is the one that has the motor information plate. Hold that in place.

Then insert and begin tightening the screw on this side. But again, don’t tighten it all the way; leave a gap, as on the other side.

Now we look inside the motor. We want to be sure there are no errant wires sticking out, which would interfere with the armature.

Here you can see the brush lead is neatly tucked away to the side, as it should be. Check to see that the other side looks the same.

Once we’ve confirmed there is no wiring sticking out, we go back to the first screw and tighten it all the way.

Then do the other side.

And that’s that, the motor housing is now ready to accept the armature again.

Go on to Part 17: Cleaning the Commutator


  1. Inserting the screw first.....that is why you are the teacher and I the student.
    Diana in CNY

  2. Again - Fantastic series, Rain! I am enjoying every 'chapter'. -Shari

  3. Hi Rain,

    Wow! Awesome information in an analogy that almost anyone can understand.

    The only suggestions I have to make are directed toward the sellers.

    First, dear ebay seller, I do not want to buy your domestic machine if you've been sewing leather with it. Even a few strips that you advertise in a video or photo on your ebay listing are likely to make me completely disregard your listing. I am a serious, well-informed buyer who is willing to pay big bucks for the right machine but not if you've been sewing leather. However, taking an old machine that's been sitting around forever, oiling it up, and then sewing leather with it, even a few times, can damage the machinery and motor in ways that I don't want to pay for.

    Second, dear craigslist and ebay sellers, advertising a vintage domestic machine as "industrial" is just advertising the fact that you, the seller, do not know what you are selling. That tells prospective buyers that you can be taken advantage of because of your lack of knowledge of your product.

    Thanks again, Rain. Fight the good fight.

  4. Question. I looked closer at your pics of the brush leads. They look like they're soldered onto the small metal clips and the insulation is trimmed/frayed back by a cm or 2. Is this correct? It's the 5th pic from the bottom. Mine looks like that and I wanted to make sure my interpretation was correct. At first I thought it was a bad wiring and needed to be shrink tubed/insulated but maybe that's how it is supposed to look?