Tension Problem On Consew 206Rb-1

[willisb]

I recently bought this machine second hand from a garment business who's owner also repairs and sells machines. After some stops and starts I got a hang of it and have sewed a few bags in canvas and leather. But there has been a reoccurring problem which now is making it impossible to sew more than a 12 in. seam before the top thread breaks. As far as I can tell, the bobbin thread is just too tight, and increasing the top thread tension to compensate just brakes the thread. and adjusting the spring on the bobbin case is moot. The thread spools out of the bobbin fine while I'm holding it, but once in the machine, the tension is far too high and is somewhat jerky when I pull on it. I've already gone through the manual, adjusted the timing, the hook/needle spacing, the needle/feed dog spacing and oiled everything, but same problem persists. Bobbin thread seems to be getting squeezed between the bobbin case and the hook mechanism on its way out of the needle plate. Any help is greatly appreciated, I was looking forward to a productive day but so far have only been successful in frustrating myself! Thanks

edit: also sometimes the thead will fray to about half it thickness, and bunch up behind needle before braking. Makes me think there is some other issue going on. I sewed an entire bag with slightly thicker thread, with the same needle. I don't know why it would stop working at this point.

Edited June 11, 2012 by willisb

[Wizcrafts]

Check the bobbin for burrs, or starting thread stubs protruding inside or outside the holes.

Try this:

1. Load a bobbin into the case and make sure the thread goes under the spring and pulls out smoothly and easily.
2. Insert the loaded bobbin case into the shuttle and use the top thread to draw up the bobbin thread.
3. Lift the feet and keep the needle up.
4. Pull on the bobbin thread. Is it now tight? If so, unscrew the throat plate and Grok what is going on under there.
5. If not, turn the wheel until the needle is down and starting up.Pull the bobbin thread again. If it tightens up at a certain point of rotation, try to identify what parts are squeezing the bobbin thread. A flashlight, or aim-able work lamp will help.
6. It may help to have a narrow strip of leather under the feet to test under actual sewing. But, check it without any payload first.
7. Check the feed dog plate to see if it is causing the thread to jam.

Edited June 11, 2012 by Wizcrafts

[Ferg]

Wiz,

Could part of his problem be "Too small needle" ?

ferg

Check the bobbin for burrs, or starting thread stubs protruding inside or outside the holes.

Try this:

1. Load a bobbin into the case and make sure the thread goes under the spring and pulls out smoothly and easily.
2. Insert the loaded bobbin case into the shuttle and use the top thread to draw up the bobbin thread.
3. Lift the feet and keep the needle up.
4. Pull on the bobbin thread. Is it now tight? If so, unscrew the throat plate and Grok what is going on under there.
5. If not, turn the wheel until the needle is down and starting up.Pull the bobbin thread again. If it tightens up at a certain point of rotation, try to identify what parts are squeezing the bobbin thread. A flashlight, or aim-able work lamp will help.
6. It may help to have a narrow strip of leather under the feet to test under actual sewing. But, check it without any payload first.
7. Check the feed dog plate to see if it is causing the thread to jam.

[Wizcrafts]

Wiz,

Could part of his problem be "Too small needle" ?

ferg

Not likely Ferg. He stated this: "The thread spools out of the bobbin fine while I'm holding it, but once in the machine, the tension is far too high and is somewhat jerky when I pull on it." Something is pinching the bobbin thread as it feeds out of the bobbin case, past the shuttle carrier and up through the hole in the feeder or throat plate. It might could be the feed dog itself squeezing the thread. Once he hand-wheels the machine with the throat plate off, the cause should reveal itself.

Thought! If the bobbin itself is slightly fatter than the space between the clamped on bobbin case and interior of the shuttle, the thread will be squeezed tightly.

[Wizcrafts]

willisb;

Check your bobbin case on the inside end, with the bobbin removed, and see if it has an anti-backlash spring. If so, remove the spring. I'll wager that this cures the over-tight bobbin thread problem.

[willisb]

Hi thanks for the help, the problem seems to have resolved itself. I put the bobbin in, then draw the thread up through the needle plate, then I release the bobbin case and move it out just a bit, then click it back in. This seems to clear whatever little protrusion was in the way. I also wound a new bobbin with a more consistent tension. Thank ya'll for being attentive,

Willis