Kenmore 158 Foot Pedal: Fine Tuning

After a week of use, Mary decided the single additional graphite disk in each stack produced a too-high initial speed when the sewing machine started up; this being a matter of how it feels injects some of trial-and-error into the repair.

Shaving a graphite disk down from 0.8 to 0.4 mm seemed entirely too messy, so I snipped squares from 0.40 mm = 16 mil brass shim stock, nibbled the edges into a polygon, and filed the resulting vertexes to produce a (rough) circle:

Kenmore 158 Foot Pedal - 0.40 mm brass shims
Kenmore 158 Foot Pedal – 0.40 mm brass shims

Each stack looks like this:

  • 1.5 mm graphite disk (double-thick)
  • 0.30 mm brass (original part)
  • 0.79 mm graphite disk
  • 0.40 brass (new part)
  • The rest of the stack

Protip: dump those shards onto a strip of wide masking tape, fold gently until it’s all corners, and drop in the trash. Otherwise, you’ll pull those things out of your shoes and fingers for months…

You can get cheaper nibbling tools nowadays; I’ve had mine for decades.

16 thoughts on “Kenmore 158 Foot Pedal: Fine Tuning

  1. Joe Pieczynski did a great video on turning washers from shim stock I did a few the other day and they turned out great.

    If the hole in the center is unacceptable I think you could still do something similar. Instead of having a bolt go through them and using a nut, maybe the tailstock could be used to keep them compressed against a flat faced shaft in the headstock. You’d have to do only a few shims at the time, setup would be killer and it would take far too much time of course but they would look gorgeous :)

    Excuse my madness, to a man with a lathe everything looks like a work-piece :)

    1. The standard technique seems to be a cylindrical pad on a live center in the tailstock, firmly pressing the disk against a sacrificial pad on a faceplate, doing one disk at a time. Hand-nibbling each one from a square shim certainly involves fewer high-energy failure modes…

  2. “Protip”… ugh. I surfaced a piece of rusty hot-rolled steel with a carbide-insert shell mill last week. The “chips” look more like miniature daggers and they got everywhere. I am still pulling them out of the soles of my shoes. Time to consider an enclosure for the milling machine.

    1. I’ve occasionally gimmicked up a chip shield around the Sherline tooling plate, but mostly I take such sissy cuts that it’s not a problem. There’s a sacrificial rug underfoot that very rarely gets shaken directly into the trash can, too: so far, so good.

    2. I have hard tile floor around my lathe. After a turning session (and sometimes in the middle) I use broom for the bigger pieces and then put my B vacuum cleaner to good use – the poor thing.

      I still think some sort of dust collection should work on a metal lathe, probably with all metal cyclone to avoid sucking hot chips into a bag full of dust.

  3. Also, super-glue a stack of brass shim-stock between two more solid pieces and turn the whole thing to size between centers. Heat the thing and the glue falls apart leaving you with a bunch of nicely trimmed brass circles. That may even be easier than the trim and sand approach.

    1. Cyanoacrylates and I have bad blood going back many years; neither of us seems willing to work with the other. Epoxy, now, we get along fine! [grin]

  4. From one sewist to another… it is long past time to flash the plastic and buy a new machine with a reliable control.

    1. She’s been eyeballing a Juki with a conspicuous lack of fancy computerized features. The equally conspicuous lack of an Authorized Dealer within 50-ish miles puts a crimp on toodling over to check one out; we agree that she must spend Quality Time with one before buying a new toy.

      1. Julie bought a Juki a while ago, but hasn’t used it much. So far her old Elna is the go-to machine. The bigger throat of the Juki will trigger the switch as bigger quilts work through the queue. Her sister has the same model Juki, and found that the threshold plate must be replaced very carefully, if not, she found she could trash a bobbin. With proper care, it’s wonderful.

        We had to order the machine; the local quilting shop sells Berninas and long arms, but the prices are breathtaking. ‘Sides, no room for a long arm in the designated sewing space. I could have built her shop 2X the size with the same inspections (gas and electric; building was excempt due to size) but a) I wasn’t aware of that fact, and b) the small shop is a puppy-mother to heat in winter. So, most of the year, she sews in the house and the shop is more storage space.

    2. I absolutely agree with you on the epoxy! I still remember the ad with one square inch of epoxied hook lifting an elephant.

  5. Maybe an electronic speed control? A gas pedal position sensor from a late model Toyota (a foot operated potentiometer) from the junkyard connected to an SCR-based motor speed control…. if it needs some massaging (signal processing) then maybe put an arduino board in the middle…

    1. There’s a vast backstory on my attempt to add electronic speed control to ancient Kenmore 158 machines; searching for kenmore speed control or kenmore arduino, then following the linkies, will reveal just the thinnest upper layer of that sediment.

      Suffice it to say:

      • Various constraints eliminate all the easy, obvious solutions
      • I’ve gone as far as I can with the OEM universal-wound motor
      • The right solution starts with a brushless DC motor

      It definitely kept me off the streets at night for quite a while!

      1. Whatever became of that in the end? I don’t recall any denouement, it seemed to be moving along fine until it just sort of faded out…

        1. That’s almost exactly how it ended.

          The pulse drive controller worked, in the sense that it provided decent low-speed torque, but it wasn’t sufficiently quiet for Mary’s liking and tended to unscrew random fasteners over time. The tiny screw on the bobbin carrier wouldn’t stay put, even with a dose of low-strength Loctite to allow normal adjustments. That screw sets the bobbin thread tension: any variation wrecked stitch consistency and that wasn’t acceptable.

          Having the Crash Test Dummy walk itself off a table during a high-speed run didn’t do it the least bit of good, either, so we eventually harvested some spare parts instead of transplanting the sensors & controller to a different machine.

          It was a wonderfully educational project, though, and well worth the annoyance. At least for me. [grin]

  6. This place may be able to provide you with an appropriate replacement. I bought my significant other a machine from here that looks like it came off a showroom from the 50’s or 60’s with all the solidity and none of the electronic geegaws that implies.

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