I picked up a 1951 Singer Featherweight sewing machine recently. It's in great shape, except that even after applying lots of oil, the shaft which rotates the bobbin assembly resists rotating through about half its travel. Presumably this means the shaft is very slightly bent, although I can't detect any distortion visibly. So, while I can still turn it by hand, the motor isn't quite up to the task. Here's a photo; the problem is the light shaft running down the middle:
Here are the solutions I can think of, but I'd appreciate your comments:
- Remove the shaft by drilling out the dowel pins or perhaps by careful heating of the caps with a torch to loosen the pins. Then either: a: turn the shaft on a lathe so it moves more freely. (How much play might this introduce?) b: cut a new shaft and make sure the caps end up at exactly the right places. (Apparently, bobbin position and rotation needs to be rather precise)
- Leaving the shaft in the machine, heat the center of the shaft until it just starts to become plastic, rotating the shaft continuously as it cools, so that the mounts themselves ensure smooth rotation. Potential problems would be twisting of the shaft causing the caps to be at the wrong angles, and expansion of the shaft preventing any rotation while it's hot.
-J