New Cobra Class 18 Tension Issues?

[TKLeather33]

So yesterday I got my new Cobra Class 18 machine, got it all set up and started stitching some things and trying to get familiar with the machine. I finally got everything so it was going good and all bolted together and such. It really didnt take very long and I thought the machine was pretty darn close anyway. So I start stitching some 6 oz chap leather to a scrap of 10 oz veg tan and it will stitch beautifuly and then have about 10-15 stitches right in the middle of the line that pull the bobbin thread all the way up and then stitch nice again. all with no adjustments made anywhere just out of the blue. it seems that when I change speed it tries to do this. I havent called anyone yet as I just got this going late last night and I am sure it is an operator issue not a machine issue as this is my first real machine. I have an old singer 31-15 that I was running by hand.

I am running 138 top and bottom, I am using the thread that was supplied with the machine and the machine is threaded just as it came to me. I know that Art has this unit and I am hoping some of you GURUS can help lead me in the right direction.

Thanks in advance and have a great day

[Wizcrafts]

It could be caused by the thread being too springy, or not feeding off the top of the cone.

[TKLeather33]

Thanks Wiz. The thread is a brand new spool (brand new machine) and it is coming off the top. I am wondering if it has something to do with the thread controller thing after the tensioner. when I opened the box the thread was just hanging below this part and I cant understand what the heck the instructions are saying in regards to how to thread it. With there were pictures that you could actually see in the manual

[CowboyBob]

Maybe this will help.

[TKLeather33]

Thanks bob but mine is quite a bit different than that

[Sylvia]

I bet I know what's going on... its common... and is "hidden" unless you happen to change spools of thread. Some times the thread will wrap itself around the spindle which temporarily causes extra tension. I had forgotten about that and had fits with my old singer for a while... then discovered the problem by removing the spool during a thread change. There it was, 3 or 4 wraps of thread around that spindle. The good news is that its and easy cheap fix.

Hit your sock drawer for that miss matched sock. Put your spool of thread in it and pop it back on the spindle and thread normally. The sock keeps the thread feeding properly....

[TKLeather33]

so put the sock in a position that holds tension on the thread on the spool?

[TKLeather33]

One more dumb question. What does the thread controler do? I think that is what it is called. it is after the tensioner and before the arm that pulls the thread up.

It says in the manual that you can rotate it to have more or less effect on the thread, the trouble is I dont know what it is supposed to do in the first place haha

[Wizcrafts]

  On 11/15/2013 at 7:04 PM, TKLeather33 said:

One more dumb question. What does the thread controler do? I think that is what it is called. it is after the tensioner and before the arm that pulls the thread up.

It says in the manual that you can rotate it to have more or less effect on the thread, the trouble is I dont know what it is supposed to do in the first place haha

The check spring is used to keep the thread taut as the take-up occurs, which reduces shock and awe. This is mostly during the take-up and slightly in the take-down cycle. The longer the stroke of the check spring, the longer the thread is held taut. However, if the thread continues to be taut during the hook's pick-up point, the loop will dissolve before it can be picked up.

[TKLeather33]

Well it is still pulling the bottom thread up for about 8-10 stitches then back to normal. when it stitches like normal it looks great though.

[Wizcrafts]

  On 11/16/2013 at 4:06 AM, TKLeather33 said:

Well it is still pulling the bottom thread up for about 8-10 stitches then back to normal. when it stitches like normal it looks great though.

Something happens during those stitches to cause the tension to go awry. The problem is either in the bobbin/bobbin thread, or the top thread and its path. Watch the top thread as you sew a long strap. You may see it twist around a post, or even itself.

Make sure that the bobbin thread feeds under the bobbin spring and stays under it. Load the bobbin so it feeds counterclockwise into the slot in the bobbin basket. Check the bobbin to see if the starting thread has a stub sticking out that might be catching on the case, basket, or shuttle.

[Red Cent]

What Wiz said. I found that when that problem happened, the thread "caught" on the spool thread. Any time the thread is impeded, no matter how little, it creates super tension in those discs especially the lower one.

[tnawrot2]

You said you are using a piece of scrap leather, if you are using any belly leather it has different consistencies and firmness that would cause your problem.

[TKLeather33]

You know I am using some pretty bad chap scrap and I was wondering if that was it as well. I put some projects together last night and stitched em this morning and it went well. But I have run a bunch off of the brand new spool, and adjsuted a few tensions as well so maybe we cured it. Thanks for all of the input and help guys