Bobbin birdsnest mess

[dgkfit]

hello all,

   the only reason i am writing this is that it is sunday, and i have a deadline to meet.  i bought a cobra class 4    2 weeks ago and it has been a steep learning curve. the only reason i bought a cobra instead of another machine is that the cobra dealer was closest to me. i want to say THANK YOU to david and steve at leather machine co and also cowboy bob at toledo industrial sewing.  both have given great service and help either here on on the fone.

    below is a foto of the problem i have been having with my machine.   it seems to have a bad habit of making a birdsnest mess with the bobbin.  we might have fixed it today.  we tightened up the bobbin tension and then re-threaded the machine.  it seems as tho when taking the thread out the top threading path gets out of its proper place.  the tiny set screw that holds the bobbin tension is way too small and way to far in to be easy to adjust.  and, the head on it is tiny, and i am afraid of stripping out the slot for the tiny screwdriver.  but is this the way to fix the problem, or is there something else i am doing wrong?  i am sewing 1680d ballistic nylon with #277 thread top and bobbin.

   thank you all   dale   501-358-2783   call if you like

[dgkfit]

i tried to sew with it again and it sewed for awhile and then stopped and the needle went up and down in the same place.  here is the foto.  thank you for your calls.  dale

[brmax]

Dale,  I'm not understanding the problem in order. So I would purchaser another bobbin setup for 277 for a start, then with your friend  sew some scrap in several straight lines only. I say this to better understand if an issue starts inline or at or after a turn in the fabrication.

Possibly send out the project fabrication until this system is worked to the fine tune setting which always is a case for a production.

In any case a step by step is needed in this online thing, but a certain set of parameters need checked, set and seen from this side "clearly".

Good day there

Floyd

[JREESER1]

With my Cobra I had to make sure, every time I began to sew, I held the thread ends taut from both bobbin and the needle for 3  full stitches. When you don't hold  the thread ends or you only keep the needle thread tail taut a bird's nest will result, just like your picture. And make sure to run practice pieces anytime you make even small adjustments. Just to insure you don't mess up the project piece.

jr

[Wizcrafts]

What can sometimes happen is that if the top tread twists too much, on its way to the top tension disks, it can actually move up and out of the primary tensioning area. It may even move to the top, yet appear to be in the disk when viewed from the normal operation angle. This would mean little or no top tension, resulting in all the top thread being pulled under the leather.

The same thing would happen if the tension adjuster nut backed off the beehive tension spring on top. All you would have would be the bottom rotating disk and check spring to tension the top thread.

A third variation would be the bobbin thread binding in the bobbin case. This could cause the top thread to be pulled to the bottom. But, I think you would notice if the bobbin thread was jammed before you started sewing.

If it turns out that the top thread is not staying down near the center of the top disks, feed it through one hole and around and through another hole in the post thread guide on top of the machine. Make sure you feed the thread through the steel guide in front of the top tension disks. It will help if you loosen the screw on that loop guide and lower it until the foot lifter rod just misses it when you lift the feet with the foot lifter pedal.

[sandyt]

I Don't have any experience with Cobra or the material you are sewing.

But does this also happen when you sew thicker material? A few layers or thick leather?

The material in the picture looks pretty thin for a heavy duty machine like that with that needle and thread size.

Again, no experience, just a thought.

Sandy.

[dbusarow]

14 hours ago, dgkfit said:

 

Hi dgkfit,

It's now Monday morning so I'm sure you will be able to contact someone at Leather Machine Co.

But..  I bet you could have gotten hold of someone there yesterday too.  Spectacular service is part of what you end up buying from them and the other sponsors here.

Back to your problem,  this is almost 100% certain to be due to you not holding the top thread tight enough for the first several stitches, at least 3, 4 or more won't hurt.  Voice of experience, and I note that it has already been mentioned in this thread too.

As far as adjusting the bobbin tension.  Well, there's a tension adjustment screw there, and it does need to be set correctly.  But it is also, based on experience, the last thing to touch when experiencing a tension problem.

The bobbin just needs enough tension to slightly resist the thread being pulled out.

As far as the adjustment screw, there is a LOCK screw too.  Loosen the lock screw, make whatever tiny adjustment needs to be made to the bobbin tension (I use a jewelers screwdriver for this) and then tighten the lock screw back up.

 

Hope that helps!

Dan