I brought a "naked" sewing machine to the February 2020 edition of Wearables Wednesdays. Wearables Wednesdays is a regularly occurring monthly meetup at CRASHspace LA, a makerspace in Culver City whose membership includes a lot of people I love to chat and hack with. But Culver City is a nontrivial drive from my usual range. So as much as I would love to frequently drop by and hang out, in reality I only visit at most once a month.

The sewing machine belongs to Emily who received it as a gift from its previous owner. That owner retired the machine due to malfunction and didn't care to have it repaired. At our most recent Disassembly Academy, one of the teams worked through the puzzle of nondestructively removing its outer plastic enclosure. There were several very deviously hidden fasteners holding large plastic pieces in place.

https://twitter.com/Regorlas/status/1222738471518752768

Puzzling through all the interlocked mechanisms consumed most of the evening. Towards the end, Emily soldered a power cable (liberated from another appliance present at the event) to run its motor, which was the state I brought in to Wearables Wednesdays.

https://twitter.com/BarbMakesThings/status/1230383496981467136

This event was focused on wearables, so everyone has some level of experience with a sewing machine. And it is also an audience who have experience and interest in mechanical design, so it was a perfect crowd for poking around a sewing machine's guts.

When the outer enclosure was removed, a broken-off partial gear fell out. The rest of the gear was found to be part of the mechanism for selecting a sewing pattern. At the end of Disassembly Academy, our hypothesis for machine retirement was because of its inability to change patterns due to this broken gear.

Further exploration at CRASHspace has updated the hypothesis: there is indeed a problem in pattern selection, but probably not because of this broken gear. We can see the large mechanical cam mechanism that serves as read-only memory for patterns, and we can see the follower mechanism that can read one of several patterns encoded on that cam. However, pushing on the internal parts of the mechanism, we couldn't get the follower to move to a different track.

New hypothesis: There is a problem in the pattern mechanism but it's not the gear. The pattern selection knob was turned forcefully to try to push past the problem, but that force broke the little gear. It was a victim and not the root cause.

Exploratory adventures of this sewing machine will continue at some future point. In the meantime, we have a comparison reference from a friend who owns a sewing machine that predated fancy pattern features.

https://twitter.com/devoopes/status/1230732197818064897