tate_elliott

A friend of mine has a 237 that won't sew. I looked at it and think I found the problem. When the oscillating hook takes the thread around the bobbin case, it goes only to the bottom of the case and then reverses itself, leaving the thread at the bottom center of the bobbin case. When the take-up arm pulls on the thread, the thread does not continue around the bobbin case, it stays at the dead center bottom.

I'm guessing this is a timing issue in that the hook doesn't go far enough around the bobbin before releasing the thread. Does that sound right? If so, how do I adjust it? Any tutorials or guides?

Tate

Mickey2

It's a timing issue, but not necessarily the hook itself. I've had needles off sync because of dirt behind the needle clamp, when I took it appart I ended up scraping out a lot of dust and grime from the groove in the needlebar. It took me two weeks to discover it; all cleaned and reassebled the needle was just in the right place. All kinds of issues cause these things.

As the upper thread gets picked up for a ride around the bobbin case, it picks up the bobbin thread and they interlock and tighten up by the upper tensioner. The bobbin tension is there mostly to guide the bobbin thread and firm it slighly up; all the action is initiated by the hook and upper thread. In other words; I don't think the take up lever should affect the upper thread at this point; it might be just tension (non at all?, is presser bar lever up?) If I'm thinking right the takeup lever brings around just enugh thread from the top spool for the next stitch. And the tightening up happens as a combined action of the thread interlocking, needle movement and just the right tension.

purplefiend

Tate,
The Singer 237 is an oscillating hook machine, not a rotary; it sews just like you describe.
Make sure that your friend has the needle in the machine with the flat to the right and threaded from left to right.

Sharon in Texas

quiltedsunshine

If it's not letting go at the bottom, it's one of two settings. Either the return motion is off, or the thread passage is too tight. Thread passage is where the hook and driver "kiss" at the top. There should only be 1 or 2 thread width between the two. Bending forks are the best way to adjust that. Return motion is like you said, the hook doesn't quite rotate far enough before it starts back the other way. Not having one in front of me, I wouldn't be any help with that. I hope someone with more Singer knowledge can help.