Cobra 4 Problems

[KND]

I am having mega problems getting proper tension my Cobra 4. It's been months of hours, trying and giving up. Going back to hand sewing and my old crappy flatbed machine. But I am thinking it might be more than just tension. There are times when I am able to wheel the machine by hand, so, the wheel IS turning, but the rest of the machine doesn't move. Ie, the needle (and everything else) stays put, near the top of it's rotation. Im wondering if this may be effecting the tension some how, maybe if something has come loose ? Im really at a loss...

http://www.youtube.com/watch?v=y8rBZfq29_E

(I posted about the tension problem yesterday, under a different user name, but thought I should instead start a new thread because it does seem to be more than just a tension issue and I didn't want to hijack that thread. I also for some reason wasn't able to sign in under my old name, so I had to make a new account)

Here are the tension issues:

I finally got it tensioned for one type of sewing I do, took DETAILED notes of the tension settings, then went back to try and tension the other way I sew, and it took hours and hours. Then I need to go back to the first way I sew, and my notes don't work. I can't get it tensioned back to the way it originally was. Am I missing something? It's wasting so much of my time, and a lot of materials. I've asked Steve, but his feedback hasnt seemed to have helped. I am hoping someone else with a Cobra or 441 clone can offer me some tips?

The first type of sewing I do is one layer of veg tanned about 6-7oz to one layer of chrome tan 3.5 oz. I use a 25 needle, with appropriate thread.

The second type of sewing I do is min 2 layers of chrome tanned, to max about 4-5 layers. I use a 21 or 22 needle, with appropriate thread.

I have got the machine to flawlessly sew both, eventually. But every time I try and tension for the other type of sewing, it takes me hours, days. Or longer. Or I give up (and thank God my old crappy machine still works well enough!)

In these photo examples, you can see how it varies between top tension is too strong, and then too loose. I CANNOT find the balance. (and yes, the top & bottom thread are the same thickeness & brand). It seems I cannot make a small enough adjustment, so it goes between too little and too much tension immediately. Sometimes I can get it to sew normal for 5-6 stitches, but then it always reverts to one way or the other (top is too loose or too tight)

I have adjusted bobbin tension as well. It seemed to like being just off the tightest setting for the thicker sewing, and as tight as possible for the thinner sewing. But so far its made no difference..

http://img824.images...69/tensionp.jpg

[Wizcrafts]

Pull the thread out of the machine, including the bobbin thread. Close the empty bobbin case.

Place the same thickness of leather under the feet and try hand or slow machine sewing without thread.

Does the machine hang as the take-up lever is rising? Does the needle stop while the hand wheel turns?

If so, try tightening the screws that secure the wheel to its shaft! It could be that simple.

[KND]

thanks, Im just checking that now

[KND]

I did a few tests, taking out one variable each time, and it appears to be the top thread that is causing the machine to stick (whilst the wheel is still tuning) ...

[KND]

the wheel had come loose on the shaft, so I have just tightened that and are doing more tests now

[KND]

I did some more sewing tests, and back to the same tension problems. I guess the shaft made no real difference (but at least that is one less thing to worry about now)

[cajun]

the wheel had come loose on the shaft, so I have just tightened that and are doing more tests now

I have had my cobra for over a year and have tons of broken needles and have never been able to sew a project yet. Steve now says my problem is tension. I have spent hours working on that and no lucka, the last time I talked to him, it sounded like he was fed up talking to me. So the machine is now sitting in a corner with flower pots on it and I am back to hand sewing and guess I will hand sew from now on. The machine is not worth the hassle. Hand sewing sure is faster and better for me.

Regards,

Cajun

[Wizcrafts]

I have had my cobra for over a year and have tons of broken needles and have never been able to sew a project yet. Steve now says my problem is tension. I have spent hours working on that and no lucka, the last time I talked to him, it sounded like he was fed up talking to me. So the machine is now sitting in a corner with flower pots on it and I am back to hand sewing and guess I will hand sew from now on. The machine is not worth the hassle. Hand sewing sure is faster and better for me.

Regards,

Cajun

Cajun;

Why don't you start a new topic requesting help from other Cobra owners? Somebody may have experienced the same problem and knows how to fix it. I sew with a Cobra Class 4 at work and am responsible for adjusting and maintaining it. I may be able to help you get yours working right.

[Wizcrafts]

I did some more sewing tests, and back to the same tension problems. I guess the shaft made no real difference (but at least that is one less thing to worry about now)

With the hand wheel properly tightened, is everything now moving in sync? Check the other screws on moving parts you can see. Make sure screws are not loose. But, make sure moving parts are not binding.

Let's work on the top thread problems.

Grab a kitchen funnel, or go to an auto parts store and buy an oil funnel, which is just slightly bigger on the bottom than the spool of thread is on top. Make the spool into Tin Man,with the thread feeding out the long narrow spout of the funnel. Feed it up, through the thread guide hole and pull the thread. See if it unwinds from the spool, feeding through the tornado of the funnel spout. If so, let's continue wit the Tin Man concept. If not, remove the cap and we'll try something else.

Whether the funnel trick helps or not, feed the top thread from the hole in the top guide bar through the top hole in the post on top of your machine. twist the thread against the direction of any coils, to loosen it as much as possible. Now, thread the rest of the way as shown in the instructions.

Choose the correct needle and thread combination for the leather thickness and hardness you want to sew. That might be a #25 or #26 needle for #277 thread, top and bottom, depending on the hardness of the leather. Don't try sewing thick nylon thread into thin leather. This requires a different, softer type of thick thread that you are using.

Using a larger needle than required sometimes makes it harder to balance the position of the knots than if a smaller needle is used. Too small of a needle may cause the knots to stay on or near the bottom no matter how hard the top pulls. Try different size needles with your thread and stick with the ones giving the best, repeatable results.

Make sure that the bobbin spring presents smooth friction for the bobbin thread and make sure the bobbin is loaded to feed backwards to the slot in the case. Remember what I told you last night about checking the bobbin for any starting thread that may be looped out of the little hole and around the top of the bobbin disk. These leftover threads are grabbed by the spring inside the bobbin case and cause tension variations.

Make sure the top thread is not twisting around anything it should be passing through. Set the tension adjustment around the middle of the top disk adjuster. Sew a few inches and see what you get. Adjust the top adjuster for the best consistent result.

Hints:

If both top and bottom stitches are loose, tighten both top and bottom spring tensions. If both are dug into the leather too far, loosen both tensions. If the knots are all on the bottom, tighten the top tension. If the knots are all on top, loosen the top tension. If the knots are all over the place, tighten the bobbin case spring and try again to balance the thread.

Finally, change to a different brand of thread and try again. If you can't do that, spray the spool with silicon, or place it into a can of pure mineral or sewing machine oil for a few minutes. Dry off the excess lube and try using your lubed thread. If this helps, consider buying only pre-lubricated thread (e.g.: http://www.tolindsew...com/thread.html).

Another thing that just came to me: Make sure your thread doesn't say RT, or right twist! Our single needle sewing machines require left twist, also known as LT, or Z twist.

Edited January 20, 2012 by Wizcrafts

[dirtclod]

KND in watching your video i noticed you have the thread running twice through the guides on both of them. Not sure if that's your problem, but i thread my machine just like Bob does in this video at the bottom of the page going through the guides one time http://www.tolindsewmach.com/cb4500.html . On my machine i set the tension sewing through two pieces of chap leather and it's good for ever thing else and i sew 3/4 " thick quite a bit.