Kenmore Model 158 Pedal: Graphite Disk Refill

The pedal on one of Mary’s Kenmore Model 158 sewing machines lost most of its speed control abilities, which past experience has shown indicates its carbon / graphite disks have deteriorated. Fortunately, I still have a supply of disks from the Crash Test Dummy machine and have gotten pretty good at dismantling the pedal housing.

While I had the pedal apart, I filed the brass contact plates smooth again:

Kenmore 158 Pedal - graphite disk contact

Kenmore 158 Pedal – graphite disk contact

Most of the deterioration happens within half a dozen disks snuggled up against those contacts, a few more on the other end of the stack against the graphite button applying the pressure, and an occasional grimy disk in the middle of the stack.

I filled both stacks flush to the top of the ceramic housing, then removed one disk from each to let the brass contacts slightly compress the stacks:

Kenmore 158 Pedal - graphite disk refill

Kenmore 158 Pedal – graphite disk refill

A quick test showed the control range started a bit too fast, so I removed one more disk from the stacks, buttoned it up, and it’s all good again: a slow start with a good range.

  1. #1 by Keith Neufeld on 2018-08-22 - 07:32

    Based on the effort you’ve put into this, I’m guessing you don’t have a source for more carbon discs? I find they deteriorate quite rapidly when the pedal falls from the sewing table to the floor.

    • #2 by Ed on 2018-08-22 - 09:57

      Mary’s unusually good at not dropping things, so we haven’t discovered the pedal’s shock sensitivity. [grin]

      I’ve been maintaining two other pedals with disks harvested from the Crash Test Dummy’s pedal, but I foresee a triac-based foot pedal in our future, no matter how awful they are.