Using Bonded nylon thread In a 111 w or other walking foot.
You need bobbins that fit the bobbin recess correctly. Some are too small and allow the bobbin thread to escape.
To stop the bobbin overrunning sometimes a hand made textile friction disk washer or multi point drag spring helps. I prefer the textile disk. Thin canvas or other material, you have to experiment, not too thick, the bobbin should not touch the bobbin retaining arm that would create excessive tension.
The thread release that allows the thread to travel under the throat plate must also be set correctly release the thread as the needle rises and the thread loop is pulled up. This setting can vary depending on your thread thickness.
Best way to check is to thread the machine and then using the same thickness of materials you intend to stich hand turn the machine for a maybe a dozen stitches first and then see if the thread travels around the bobbin case and is released without jerking. Check if the bobbin overruns excessively, if you see a loop pop up something is wrong with your settings. Make sure that the thread is correctly tensioned under the bobbin case tension spring. As a starting point set this tension to just enough to create a smooth (light pull) on a finger pinch.
I would like to have posted another image of the upper threading Process the website would not allow it.
Best way to check is to thread the machine and then using the same thickness of materials you intend to stich hand turn the machine for a maybe a dozen stitches first and then see if the thread is jerking through the tension disks. When the take up arm rises to the top pulling the thread up from around the bobbin case and thus forming a new stitch as soon as the take up arm starts to fall the thread goes slack for a short time until the slack is taken up by two mechanisms,
1 the rotating hook starts to pull the thread down into the throat plate and around the bobbin case, It has to take a fraction more thread because it is needed to form a new stitch. At that point there is quite high thread tension. This is where the tension spring (Not the tension disks at this time in the discussion) come into play. The setting of the tension spring is quite important its action is similar to a shock absorber in a car. It soothes out the flow of the thread and reduces the tension peak. It should be set just high enough to control the thread, Hand turning the machine on a test piece is a good start in setting it.
The thread tension disks are often set too high in my experience, usually because the hook release is wrong or the bottom tension is too high.
(I am assuming here that the Hook/Needle/feed timing is set correctly and that the correct needle is being used for the particular thread choice)
The above is how I approached a machine when the operator said it did not work when most of the time it was just a matter of getting the thread control right.
We sewed a lot of bonded nylon
