Bobbin winding troubleshooting

[grep]

I got a Seiko STH-8BLD-3 a few weeks ago. This is my first industrial machine, though not my first sewing machine.

Thus far, I've used it to make a large portfolio style case out of nylon packcloth and webbing. The machine performs wonderfully, however, I have run into an issue when winding bobbins that I wondered if any of you might be able to steer me in the right direction with...maybe I'm missing some adjustment (followed the manual as much as possible, but it's definitely not all there grammatically).

So I've got the bobbin winding evenly (after adjusting left and right to find the sweet spot) until the point where the thread begins to contact the release lever/spoon. At this point, the thread seems to get stuck on that side of the spoon, causing the bobbin to continue filling unevenly on that side until enough pressure builds to kick the winding mechanism off of the belt. My workaround at this time has been to stop sewing and do a dedicated run to fill a bobbin, and when I reach that trouble point, apply side pressure to the thread to help it move across and keep the winding even until the release is tripped.

It seems to me like this wouldn't be an issue if that lever/spoon were as wide as the inside of the bobbin, however, I can't see why it would've been designed this way if that were a problem. So, my second guess is that I'm missing something in the adjustment process.

I'm attaching two photos. This first is an empty bobbin mounted on the winder, to show the difference between the bobbin width and the release spoon. The second is a mostly filled bobbin, after it begins to fill unevenly to one side of the spoon.

I'm using class M bobbins, with 138 bonded nylon thread.Thread tail goes through a hole on the right, then is fed through the center to bind the bobbin to the winding shaft (bobbin spins on the shaft otherwise)...a little trick I figured out on my Singer 403a that is missing the spring, but I'm not sure if it could somehow be a contributing factor.

[CowboyBob]

You need to loosen the screw on the tension adjustment bracket (which has a slot in it) & move it to the right alittle until it starts to track evenly side to side.

[grep]

24 minutes ago, CowboyBob said:

You need to loosen the screw on the tension adjustment bracket (which has a slot in it) & move it to the right alittle until it starts to track evenly side to side.

Thanks for the response Bob! So, that was the initial adjustment I performed to get it winding evenly (per the manual). What I found was that I got to a point where there's a small (few millimeters) window of adjustment left or right where it will wind evenly (up to the spoon), but positions inside of that window only appear to affect which side the thread gets stuck and builds up on once it reaches the spoon..

If you can clarify, am I shooting for an extremely minute (less than a millimeter) adjustment at this point?

[Wizcrafts]

Try tightening the spring on the tension disks. If the adjuster nut has bottomed out, add a washer as a spacer to gain another 1/16th of an inch of tightening.

[grep]

41 minutes ago, Wizcrafts said:

Try tightening the spring on the tension disks. If the adjuster nut has bottomed out, add a washer as a spacer to gain another 1/16th of an inch of tightening.

Doh! Just tested it out, and that was exactly it!

It seems like fairly heavy tension...which I suppose it would be for stitching, but for winding it's great. The physics of it make perfect sense. Learn something new every day.

Thank you both so much!

[DonInReno]

Good call Wiz