Fixing Bad Motor Wiring Insulation Tutorial
 

If you have a motor that the wires are good but the insulation is brittle and cracking, or just damaged, all is not lost. This is a relatively easy way to fix the motor leads.
I take no responsibility for this, but it is how I fix the wire insulation on these motors.

Overview. What you are doing is removing the motor, opening it up and pulling the wires out of the motor case, breaking off the old insulation, twisting the wires to make them neat and tight for new insulation and then cutting them so you can get new insulation on the wires by using heat shrink tubing.


First open the case up and expose the wires in the case. Remove the bad wire insulation by cracking it off, preferably by hand. (extreme left in this picture)

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Twist the entire wire clockwise to get them tight so you can cut them about 1.5" away from the wire end if you are going to reuse them as I did in this example. I took a picture of the wiring so when I put it back together I know where things go. (Take the picture. Trust me, it might come in handy later.) Notice the bad insulation.

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I use two sizes of Heat Shrink Tubing so I can have at least two layers of insulation on the wires. I use 1/8" and 3/32" tubing.
I "Tin" the ends of the wires with Electrical Solder and I always use Flux.

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Tin both of the ends to be connected. In this case 2 wires, 4 tinned ends.
Slide the heat shrink tubing onto the wires BEFORE you solder them together. Otherwise you will not be able to slide it over the looped end. Note in the picture you can see two unshrunk tubes on the long length of wire.
With both ends of the wire tinned, heat them and overlap them just a bit so you don't get a huge bulge of wire and solder, but overlap enough to give it strength.

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Once you have them soldered, slide the tubing over the bare wire you soldered and heat it to shrink it to the wire while butting the ends of insulation tight to each other for a good seal. Do not overlap them at this point if you are putting another layer over this one.

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Be careful to not shrink the other tube while you are doing this step.
Slide the second layer over the seams of the first layer and shrink them. You should never have two seams on top of each other, but covering each other.

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I used a crochet needle to grab the looped end and pull a third layer over this second one to provide further insulation and make it all look neat and tidy. I did not show this step however. It wasn't easy and it was not totally necessary either but that extra thickness of a third layer is nice insurance. But I feel that two layers are adequate.
Clean and put a drop of oil on the shaft, check the brushes and clean inside the case, clean the armature, and put it back together as it came apart.

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I hope this helps.
~Grant~

Thanks, Grant.

You make it look so simple. Thanks!!

Very nice Grant you did a great job here.

Greatly appreciated and much easier than a total re-wiring of the machine with new wire.

More! More!

Very well done. Thank you.

Thanks Grant. Will definitely keep this for further reference.

Grant, thank you for this tutorial! I am just learning how to solder and about motors so this is great. I have seen wiring connected 2 different ways. One by twisting the wires together and soldering them and the other tinning the ends and connecting such as you have done. In some situations it looks like getting in there to twist wires is difficult! Are both ways just as secure?

dearr mrs sewnsew (no relation) a good mechanical connection is desirable, as weil as the solder. Believe it or no, most solder doesn't conduct as well as copper to copper. The solder keeps things from coming undone and helps prevent corrosion and oxidization out of the joint. twisted together in a neat inline manner so the heat shrink can go over is what you are looking for usually. Twisted bare conductors under a wire nut is best left to house wiring and large appliances. Also there are some heatshrinks that are more resistant to wear. look at buyheatshrink.com for explanation of what types are available. Myself, i like using vintage style cotton over pvc insulated, twisted wire and replace all the old stuff.

Thanks Jim. That makes sense. Haha..yeah same name..no relation. heehee

You are welcome Mrs. SewNSew. Unless you are using it to swing on or pull cars out of a ditch, you don't need to twist the wires.:) You can see more wiring tips on my page. The link is below.
~G~

Grant,

Lousy dial up, your pics wouldn't open completely. Too big and too many on one page.


OK, I have a question for you. When using heat shrink I have found it very difficult to get it to bend. Heat shrink is stiff enough with one layer, how do you get two and three to bend?

Joe

that's one of the reasons why they make more than one type of heatshrink. I can't locate stuff locally that I'm happy with, that's why I rewire as much of it as possible, and just heatshrink, liquid tape the junctions. But to each his own... That link I posted above shows one type that is like a braided heat shrinkable covering. Now that might duplicate the appearance of some of the vintage gear and be a little more bend-y to boot.

I am working on a motor very similar to the one you showed today. I have re-wired it 3 times, but I am a beginner and am still working on developing my skills. I was concerned since I was running out of lead into the wrappings whether I would be able to twist my wires together. I pre-twisted the wire I wanted to bring in so it had a spiral to it and then was able to get a decent connection to solder. This is a test motor to practice a few things prior to working on my Singer 15-125. So far, so good.

I took photos prior to taking it apart and when I match the same distance the belt pulley? was originally there is about 1/8 play in the shaft back and forth. The brushes are still in contact with the armature either way, but is that normal? I am not sure if there is a standard tiny amount or whether it all relates more to getting the positioning right for the belt on the machine.

I see the braid at heatshrink.com is expandable, not heat shrink. I wind up using a short piece of heat shrink on the end to keep from unraveling

a small amt of endplay seems pretty comon. You csn put in .35" Izf shims yo take out some, but not all unless you're reslly dure of brush armature alignment. U can check it w flashlight thru vent holes.

Awesome tute! Thanks is an understatement! :)

Joe, There are two main types available to me. The kind I use is more of a rubber product. There is a plastic type that does not bend well and is harder to work with.
~G~

A small about of play is normal like Oldsewnsew said. Make sure that you didn't loose any of the spacers that look like washers that are on the shaft to prevent too much play. As far as your alignment goes, as long as the belt is straight on the pulleys, it is good.
~G~

Yay! Reporting back I had good success with the "test" motor! Your tut really gave me some confidence in working on it because it is an almost exact replica to the one you showed. After getting the new wires on I used the CRC Lectra-Motive spray to clean it really well. It seems to have taken care of the oily bits. After allowing it to dry I used rubbing alcohol on a cotton swab to carefully clean the commutator. That did a pretty good job without me having to try sanding it. I got the motor back on the machine last night and I would call it a success! Now I have some good practice in before working on my green 15. :thumbup:

*I just realized that the saved motor/saved machine is the one in my avatar! Pinky thanks you!

If you do have discernible play, I like to run the motor with no belt, and see if I need to adjust the bracket to improve the lineup, that way the brushes aren't on the edge of the commutator. If you take another one apart, you might see if you can salvage shim washers from a "junk" motor and take out some of the play. (but not all)

Thank you Jim. I did adjust it to the point where the brushes weren't running right at the edge of the commutator. That looked like it could cause problems. Then I adjusted with the bracket when I attached it to the head to line up the belt well. I feel so good today. It's such a nice feeling to save a piece of the past from the junk bin. Now if I can just find a zig-zag foot for it! :D

Is it low or high shank zz foot?

It's a low shank one. :)

very easy to find low shank - check sew-classic - she has good prices and she is fast. There maybe some place more local for you if you dig around.

I am such a noob lol! I had to find a site that explaned low-shank vs. high shank feet to figure that out. Thank you Miriam. I am guessing that any low shank feet will fit then? It has the 2 forks that wrap around the bar. I should try my Elna feet. Maybe that would fit?

Grant,

Ah ha! Now I understand. I'll bet the kind commonly available at the local hardware and auto pts stores is the harder plastic kind. I've never found the rubber type.

I tried to open the link on heat shrink yesterday and my machine wouldn't open it, I'll try again.

Joe

Elna uses short shank so they should fit.

After I got over the temporary brainfart I googled zig-zag foot. This was a different style than my brain picture was searching for, but fits just fine! Yeah for the extra parts box! Thanks for getting my wheels turning.