friquant

I'm working on this Singer 257 which has a drop-in bobbin. It's the first drop-in bobbin I've really studied, and this one acts like a ratchet...only allows motion one direction. In this video first I'll move the handwheel forward, which works fine. Then I'll move the handwheel in reverse, and you will see the bobbin case ride up on that stud in the back. At that point the handwheel won't go any further that direction.

VIDEO: https://youtu.be/jt-ffYrLh9A

Here are some photos of the stud.





So far I'm thinking maybe shim that whole piece to ride a little higher (washers) so the bobbin case won't climb over the stud when the hook moves in reverse.

OurWorkbench

Why are you turning the handwheel in reverse?? That is what causes major thread jams. Also the reason why some people have trouble treadling, especially when they don't start the handwheel by hand when they start treadling.

cashs_mom

Exactly my thoughts Janey! I've been told to never move the handwheel the opposite way! That is a major cause of problems.

friquant

Is it only certain types of bobbin cases that jam up if you turn the handwheel in reverse? I've not studied a drop-in bobbin machine in detail until now.


I suppose the main use cases for moving the handwheel in reverse would be:

1. Upon finishing a seam, but the take up lever went a little past top dead center, so I want to move the handwheel in reverse to put the take up lever back at top dead center before pulling the goods out from under the presser foot.

2. Upon finishing a seam, after bringing the take up lever to top dead center, but when the material is rather thick then I might move the handwheel in reverse to bring the needle to its top dead center so the needle is not sticking into the material at all.

3. Sometimes if there's a thread jam I want to rock the hook back and forth gently while tugging at the errant threads to pull them free.

4. When using the marks on the needle bar to set the timing, if I go a smidge past the mark I would want to go the other way to bring it back to spot on.

cashs_mom

You don't need to move the handwheel backwards to finish the seam. Just take one more stitch or part of one forward until the take up lever is at the top. I've never rocked things back and forth to remove a thread. Only forward.

Farmhousesewer

If it is a rotary rather than an oscillating then it only goes in one direction.

OurWorkbench

From my understanding, Yes! - Long Shuttle, rotary and oscillating and I believe even transvers shuttle machines. I think there was one machine that could be treadled either direction, but needless to say extremely rare and I haven't been able to find the patent to try to figure out how it worked.. Also there were quite a few treadle machines which had a brake of different types (lever or ball) to prevent the wheel from going the wrong direction.


As cashs_mom said, one can take a stitch or two beyond the edge of the fabric. OR can use leaders/enders or spiders to begin and end seams. It tells about these at https://flourishingpalms.blogspot.co...nd-enders.html

Here again one could use leader and enders or spiders to move the seam past the presser foot. Also, I think that they should be coordinated and if you are using a fabric that is so thick that this is not the case, than you probably shouldn't be using it on that machine.

While I will admit to rocking the handwheel to free a thread jam, not more more than a couple of degrees and certainly no more than that.

Fortunately I have never had to actually time a machine, by setting to the mark on the needle bar, that really does not make sense to me as to why you would want to turn the handwheel in a direction other than what was intended.


There are some machines that the handwheel goes the other way, but you always want to turn the wheel the way that it was intended to sew.

friquant

For the curious minded: After some experimentation I discovered that on this machine the bobbin case only climbs over the stud when turned QUICKLY in reverse. For example turning the handwheel 180 degrees in the course of a third of a second, the bobbin case will bind against the inner face of the hook body.

But if I move the handwheel slow and smooth in reverse (like a quarter turn per second), the bobbin case stays planted at the bottom and the hook is able to keep moving. (Meaning the bobbin does not bind mechanically (ratchet) against the body of the hook).

On this machine (your mileage may vary), even with the machine threaded (with or without fabric under the presser foot) I can move the handwheel in reverse for several revolutions SLOWLY without any problems. The hook never picks up the thread, no stitches are formed. The bobbin case never binds against the hook, the thread never binds into a mess. And afterward I can go back to stitching in forward and the forward stitches are well-formed.