Domestic Motors

[friquant]

@Darren Brosowski once told me you could put a domestic sewing machine motor on an industrial sewing machine, as long as it was not a walking foot. Here is my riff on that.

Singer 31-15

245mm plywood machine pulley

1-amp, 7000rpm universal motor

PU belt

Several wood screws were used to hold the plywood to the hand wheel. My inner diameter was cut a little too big, so the position and concentricity of the plywood is determined by which wood screws are screwed in more---the ones on this side vs the other. A round-tipped grinding tool was used to put a groove in the pulley for the belt to rest in. The groove is 0.5mm at its shallowest, 1.3mm at its deepest. (Crude tools, crude tolerances 🤷‍♀️) But it's enough to keep the belt in place.

You'll notice a graphite circle etched onto the left side...that was made after the first assembly by spinning the machine with the motor and holding a pencil steady against the wood. From that I was able to determine which direction to shift the plywood to get it better centered. It's easier to drive at low speeds once it's well-centered.

I'm using this 7000 rpm, 1-amp universal motor: https://www.amazon.com/dp/B0DYSNR32D

The motor came with a pedal but I didn't like the pedal so I bought this one instead: https://www.amazon.com/dp/B08D8WPWTY

The stock handwheel measures 66mm diameter, and top speed was measured at 980 stitches per minute in that configuration. After adding the 245mm plywood pulley, the top speed now clocks at 620 stitches per minute. I expected more speed reduction. My running hypothesis is that with the stock gearing it was too much load for the 1-amp motor to spin at its full speed.

And here's a video.

 

[AlZilla]

I've reported you to the Society for the Prevention of Cruelty to Sewing Motors.  

[dikman]

 (This is for Al, not you friquant).

In my early experiments I made a pulley out of wood - but it was a lot smaller! If you paint it black it might blend in better. Anyhow, as long as it works is the main thing. I wonder how it would go on a 441?