Cobra 4 Tension Help Please

[Viking Queen]

Hello,

I need some help with tension adjustments on my Cobra 4. I took some time off from stitching and now that I am getting back to work I find the machine tension elves have somehow messed up the tensions on my machine!

The bottom ,bobbin, thread is being "sucked up" into the leather. I have backed off the top tensions, recalibrated that per Steve's instructions in another thread, but the problem remains the same regardless of stitch lengh, top tension or thickness of leather. I have fiddled with top tensions quite a lot, but find no resolution. Have been hesitant to adjust bobbin tension, too tight, too loose.....I just don't know.

So, I come to the experts for advice. Here is an example of the stitches. Top row is top thread example....bottom row is bobbin thread. What say you, experts?

[Colt W Knight]

I'm no expert, but seams like you need to tighten your bobbin tension or use a smaller size needle.

[dirtclod]

Try a different thread and see if that helps.

[Viking Queen]

I have tried a smaller needle...did not change anything

Changed to different thread....still no change

Increased bobbin tension, in 1/8 turn increments until I could not hardly pull bobbin thread....no change

I switched tensions back to where they were. . . .sigh....very frustrated - lots of work sitting here waiting to be done.

It seems like this should be a simple thing...I have only been sewing on domestic machines for 60+ years so I do have an above average idea of how tensions work. Just am missing something here.

Will have to call Steve again Monday. Left a couple of messages this week.

Thank you, gentlemen, for your suggestions.

[Docado]

Hello Viking Queen

When I have problems as you described;

I unthread machine and rethread using a manual or some sort of instructions, making sure that I have thread going in or through everthing correctly.

Check bobbin thread to make sure it is coming off spool in correct direction.

Change to a new needle.

I double check needle to thread size.

Make sure machine is propperly oiled.

Change to different thickness of leather. Your example is two thickness correct? What I see: knot is a bit towards top of

leather on top thread. I would reduce top tension.

Not much help I know. I'm sure you have already done all of these things. May help someone else.

Good Luck

Docado

[Colt W Knight]

Is this a new spool of thread, or have you been sewing with this thread? Has the thread been sitting in the light for a while?

[TinkerTailor]

Are you testing stitches on bellys? That piece looks pretty hairy on the back and it appears like it may have wrinkles. Bellys can be very inconsistent in density, and i have seen stitches change alot and go from sitting on top to almost disappearing over only 2 inches due to this. I made this mistake for a short while when i got my machine, and it was frustrating because i would adjust tension to correct an issue, and then try again on a new scrap, only to see the opposite effect. The change in leather density was throwing me off. I aquired some scraps that were nicer, and then set it up correctly and i am good to go.

[sandyt]

I have been playing with leather for an few years now. I never realised, the quality of the leather coold affect the stitch quality. Can't believe I missed this lesson. Feel pretty stupid. I mostly use belly. Money issue on one hand. On the other hand, I like the wrinkles.

But it's deffinitly something to think about I guess.

[TinkerTailor]

I have been playing with leather for an few years now. I never realised, the quality of the leather coold affect the stitch quality. Can't believe I missed this lesson. Feel pretty stupid. I mostly use belly. Money issue on one hand. On the other hand, I like the wrinkles.

But it's deffinitly something to think about I guess.

Some belly leather is fine, and makes great small projects, and if you are selective can be a very inexpensive way to get into the hobby. Paying attention to how smooth the back is goes a long way. The smoother the better for projects.

However, when making machine adjustments, you need to eliminate any source of variance OTHER than the setting you are adjusting. Also, only work on one setting at a time. It is really easy to get lost and end up way out of adjustment if you adjust any system too fast, or multiple systems at a time.

Adjust one thing, look at result, if it is worse, go back. If it is better, move on to next thing. If it got better and you adjusted 3 settings, you have no way to know which one worked, or which one made it worse conversely..

[Viking Queen]

Tinker,

Thank you so much for suggesting changing the leather for my stitching sample ....I should have thought of that. The sample in the picture was on a soft old, fuzzy chunk of leather, not what I usually work on. I use 7-8 oz herman oak shoulders and it very different than the scrap in the photo. After reading your post I ran another test on 2 layers of Herman Oak 7-8 oz and came up with the same result as before.

I re-checked everything and the only other change I made was to go down one needle size from a 25 to a 24 wih 277 thread top and bobbin. Voila! No more thread getting "sucked into" the leather on the bobbin side. I still need to adjust tension as I now have knots on the underside....a big improvement, but not right yet. I spent part of the day getting my neck and both my frozen rotator cuffs (shoulders) worked on at the chiropractor, sooo not fun, and am wiped out so will fiddle with tensions more tomorrow. I am geting much closer.

Once again, I thank everyone who chimed in to offer suggestins. When you get so very frustrated it is easy to not see everything as clearly or logically as you should. Lesson learned.

Blessings, VQ

[Wizcrafts]

Since you are now using a minimum needle size for the thread, I would reduce the bobbin tension first and increase the top second. Less tension on the bottom makes it easier to pull the knots up. Just make sure there is a little back tension on the thread.

[Viking Queen]

Issue resolved....much thanks to you all. I finally got in touch with David at leather machine company who very patiently walked me through recallibrating the tensioners again, then coached me on setting proper tension for upper thread and slightly changing bobbin tension. After I texted him a photo of the sample stitches he confirms that it's now properly adjusted. It sews like a dream again!

Thank you all for your input and help....I learned much from this experience.

Now I have some projects to sew!

Viking Queen