Revving up the motor & updating lights
- artbykpgarner
- Aug 17
- 5 min read
I really enjoy working on the motor and other electrical components! I think it's just the nerd side of me that dreamed of working on and restoring old cars. I'd say that it started in 4th grade when my class was offered the opportunity to rebuild a car engine. Pretty cool to learn how everything worked together to make a car go!
For these sewing machines it’s about the smoothness of the armature, and the conductivity of the field coil. The motor is a simple wound wire rotor system consisting of a armature with copper commutator at one end and a carefully wound and varnished cluster of copper wire at the other (armature windings). This spins inside a housing that includes carbon brushes that touch the commutator while nested inside brass sheaths conducting electricity to the armature windings. The rotor assembly sits inside the stator (two windings consisting of coils of copper wire). All these things come together to create a magnetic field that - when current runs through it - makes the motor spin.
So those carbon brushes are essential, they must make good contact with the commutator. Not so much that they damage it but contact that is consistent and results in a completed circuit. If your featherweight motor seems to stall every now and then, it's a fair bet that it's experiencing a spot of unevenness or reduced contact on the commutator, so those brushes aren't able to touch properly. No touching, no current, no spinning the shaft. If you then move forward by a small amount and it goes again, then that problem is almost certain. Once going at full speed, a spot like that won’t stop you. It is just not going to get the motor up and moving if you've ended up with that patch under the brushes at a full stop.
Boy did I nerd out there! Back to this machine...
This motor was in decent shape. It had the usual brittle and worn wiring near the terminal and there was plenty of carbon dust to clear away but her lack of movement had nothing to do with her motor. It was all in that baked on sticky grease that a previous owner applied on all her moving bits. Eww!
As part of my normal motor service, I disassembled it while leaving the soldered contacts on the brush housing. I cleaned and polished the shaft to ensure smooth rotation. Then I did the same with the motor case and brushes to remove all the carbon dust.
I carefully polished the copper commutator while being incredibly careful of the varnished armature windings. Then I removed and checked the brushes for wear. I gave the brush springs a gentle tug to stretch them just a bit to ensure they make good contact. The brush housings also got thorough cleaning to remove all the carbon dust.
The next step was to remove the old grease wicks and their springs. I replaced the old wicks with new wool wicks pre-charged with sew-retro grease. I cleaned the ports as well to ensure all the old grease and grime was removed. I then re-inserted the cleaned springs followed by the new wicks.
I spliced on new 18-gauge wires about 1 inch out from the exterior of the motor. I did this by stripping about 1/3" of wire and cleaning the copper until all the old gunk is gone and the wire was as bare as possible. I then faned out the old and new wires (the new wire was stripped to the same length) and, much like you would when binding wool yard together, I enmeshed the wire strands and then twisted. I followed this with solder and finally heat shrink tubing.
Just like the rest of the machine, I cleaned and polished the exterior of the motor housing to a high shine. Then it was all put back together and evaluated to ensure it worked properly. When I was satisfied that the work was good and the motor performed well, I added another layer of heat shrink tubing to both wires to function as a protective cover – protecting the wires where they travel back into the machine.
Now for the lamp!
The lamp is one of the messier bits to work on. It has a lead sheath that always oxidizes to some degree, resulting in a lot of lead contamination that is flakey and tends to get on all your work surfaces. Some people simply clean this off and then coat the sheath in grease to reduce the rate of oxidation, but after starting that way and seeing how quickly it began to oxidize again, I decided it would be best to simply rewire the lamp.
When you tear down the machine, the entire lamp and switch assembly are removed. At that point, I cut the lamp wires just above the lead sheath and discarded the old wiring.
When it’s time to proceed, I desoldered the remaining wire from the lamp contact points and soldered new wires on in their place. Then I polished the contacts and all the other components of the lamp to a nice shine. I reassembled the lamp housing and wires to the point that the setscrew that holds the wires is in place. At this point, I used a 10-gauge solid copper wire to emulate the lead sheath. I bundled the two lamp wires and the stiffer wire together inside heat shrink tubing and voilà! We have a lamp with no lead that will keep its wires away from the gears.
The light switch got similar treatment, with the attached wire desoldered and replaced. Sometimes a light switch will be a little flakey and have trouble staying on. It seems to happen with older machines more than in the 1950s and later ones. If it’s bad, you need to replace the toggle switch with a new vintage original that is still in good working condition. If it’s not terrible, you can sometimes correct this issue by putting the switch into a vice clamp and tightening it. If it holds stable through extensive on-off testing, you should be ok to keep using the old switch. Fortunately, I didn’t have to do more that clean and rewire this machine’s switch.
On a side note, I have looked for new modern switches that might fit in this spot, but so far haven’t found anything that would work. If anyone knows of one (and not the $30 CuText model online) I would love to hear about it!
It’s at the point when I had the lamp, switch and motor back in the machine that I trimmed the wires to their correct lengths and attached the terminal connectors by both crimping the new connectors on and soldering them in place.
And, with that, this stage of the restoration was complete. Time for final reassembly, tension, and test sewing!
