The Sewing Place

Pedal overhaul and motor rebuild

Barnyard

Pedal overhaul and motor rebuild
« on: August 25, 2017, 22:13:46 PM »
I love our vintage machines I really do but sometimes they drive me mad  :angry:
I picked up a 63 Alu 201k in very good condition, remarkable condition actually. Having done the usual wiring checks I plugged it in and what a racket!!!
The motor induction noise and the foot pedal popping and fizzing lead me stripping them both down for inspection.
The motor was pretty clean but being a BAK 13-12 it is a noisy motor anyway. Induction whine on my test foot controller was still evident but nowhere near the level of the unit it came with and that lead me to the control unit within the pedal itself. Stripping it down and removing the "putty" or whatever it is that frees the threaded bars that in turn unlock the carbon / graphite disks I started the sripdown. There are 53 of these little round disks in each side with the thickest being at the bottom. That means cleaning 106 disks smaller than a half pence piece and half as thick. The way a foot pedal / motor contol works is via resistance. The carbon disks offer resistance thus slowing the speed of the motor, the upshot of resistance is heat and perhaps some noise. Panic not if your pedal gets warm, it's a genuine result of electricity. Anyhow, this pedal in particular was suffering. There was no flow through the depression of the button, it was all or nothing, very little in the graduated acceleration, slow, slow, quick, Holy Cow!
After stripping it and emptying the disks on to clean kitchen towel, one for each side. it became apparrent that all was not well. Both bottom (thickest) disks were broken as well as a total of 15 resistance disks. The noise I was hearing was electricity popping through and arching over the disks. The heat generated was due to additional resistance, half a disk alters the resistance and can induce arcing and as such increases the heat. This was the popping sound. Bear in mind that if yours does pop it doesn't mean that anything is wrong, that is just the heating and cooling process.

Finally, after cleaning every single disk and replacing the broken ones with clean replacements the pedal was reassembled. This in itself is a tricky aspect, explanion in another topic.

Plugged it all in and tested it on the noisy BAK and yes there was induction noise and hesitation but once plugged into the other machines it was glorious, so smooth and predictable, single stitch predictable. I still have fingers full of graphite as I write this, it's a dirty job and unless you want to endure a day of tedium I would just go find another pedal. If on the other hand you are like me and like to delve into the unseen parts, how they work and how to fix them then dive in, just dont do it on the kitchen table!

Barny
« Last Edit: August 25, 2017, 22:30:11 PM by Barnyard »

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Re: Pedal overhaul and motor rebuild
« Reply #1 on: August 26, 2017, 01:00:23 AM »
I'm up for this job. I have a 99 with a knee lever controller needing a clean up. How did you move the putty? Or even more importantly, what did you replace it with? My plan has been to have a spare controller for experimentation before I go to work on the ones I really need.

Barnyard

Re: Pedal overhaul and motor rebuild
« Reply #2 on: August 26, 2017, 11:54:33 AM »
I will get a picture up as soon as I can arrow. Getting the "putty" out is just a case of picking away with a small screwdriver. I don't bother replacing it as it is just there as an anti tamper measure, the screws themselves will not come undone but if you want to play it safe a dab of thread lock will do the trick or builders caulk if you want to go the whole way.

Barny

Barnyard

Re: Pedal overhaul and motor rebuild
« Reply #3 on: August 26, 2017, 12:13:02 PM »
Here you go. Notice one screw in place? This is where you will need to remove the putty.


Reverse side


Carbon (graphite) disks. Notice the colour differences. I would not put the black ones back into a pedal. These are all now spares I will use in future repairs.



Hope this helps!!

Barny



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Re: Pedal overhaul and motor rebuild
« Reply #4 on: August 26, 2017, 22:33:53 PM »
Thanks, very helpful. I have hesitated and put it off for a year. I was thinking I needed some kind of sealant, like those sticks used on envelopes. I wasn't sure if it needed to be a type of plastic, insulating the electric. There is the guide on the Archaic Arcane blog, but I didn't pick up on the putty part.