Cobra Class 4 Tension

[Klover]

Hello!

My Cobra Class 4 just arrived. First machine, and I'm trying to get the tension right. Will usually be sewing 5-6 oz - 10-12 oz, so I'm hoping to hit the right tension that can be used for most of my projects so that I don't have to mess with it too much. Will probably stick to 277 bonded nylon thread. 

The top stitch looks okay for the moemnt, but the bottom stitch looks whacky. Should I loosen the bobbin/bottom tension a little bit? 

All I've done so far is loosen the top tension about 1 full turn (achieved through small increments). I turned both top tension knobs.

[CdK]

@RockyAussie << @Klovermade some tests and posted images/video where he tested the tension for both the top and bottom thread when his machine was in balance. I seem to recall that the bottom was 1lb and the top 3lb.

That being said, the thread path plays an important role as well. My preference, based on my experience, is to make sure that the top thread is wound 1 1/2 to 2 1/2 times around the tensioner on the left side of the machine. Thread slippage needs to be minimal here, wheel needs to rotate, or I get inconsistent stitch tension. There is no standard or correct one side fits all on these machines. Thread types and thickness change how you set up as well.

Good luck with your new machine.

Edited yesterday at 09:11 PM by CdK
Missing userid

[Klover]

19 minutes ago, CdK said:

@RockyAussie << @Klovermade some tests and posted images/video where he tested the tension for both the top and bottom thread when his machine was in balance. I seem to recall that the bottom was 1lb and the top 3lb.

That being said, the thread path plays an important role as well. My preference, based on my experience, is to make sure that the top thread is wound 1 1/2 to 2 1/2 times around the tensioner on the left side of the machine. Thread slippage needs to be minimal here, wheel needs to rotate, or I get inconsistent stitch tension. There is no standard or correct one side fits all on these machines. Thread types and thickness change how you set up as well.

Good luck with your new machine.

Thank you for the input! I'll definitely check out those images/videos. And thank you for mentioning the thread slippage. I hadn't even thought about that, but I will keep it in mind! 

[CdK]

@KloverI found the thread where this was discussed. This link should take you to the page where the hammers are shown: 

 

[Northmount]

From what I can see, it looks like your presser foot pressure is too high and pushing leather into the feed dog needle hole.

Also, are you using a leather point needle?  It looks like a lot of 'blow out' due to using a conical point meant for textiles is being used. 

Both of these affect appearance besides the thread tension adjustments.

[Klover]

16 minutes ago, Northmount said:

From what I can see, it looks like your presser foot pressure is too high and pushing leather into the feed dog needle hole.

Also, are you using a leather point needle?  It looks like a lot of 'blow out' due to using a conical point meant for textiles is being used. 

Both of these affect appearance besides the thread tension adjustments.

I haven't adjusted the presser foot at all, but I will definitely take a closer look. I'm using the needle that the machine arrived with. It's a 794 S size 25 needle. 

I increased the top tension and am getting slightly better results, but the stitching seems abnormally tight, like it's sinking too far into the leather. Going to do some more tinkering today.

[CdK]

1 hour ago, Northmount said:

From what I can see, it looks like your presser foot pressure is too high and pushing leather into the feed dog needle hole.

Also, are you using a leather point needle?  It looks like a lot of 'blow out' due to using a conical point meant for textiles is being used. 

Both of these affect appearance besides the thread tension adjustments.

Yes, many things going on at the same time. I remember my learning curve and finally getting the balance of needle, thread and settings right was very satisfactory. This all takes time to build experience and confidence, like when learning the guitar, don't rush and try to force things.

[Wizcrafts]

24 minutes ago, Klover said:

I haven't adjusted the presser foot at all, but I will definitely take a closer look. I'm using the needle that the machine arrived with. It's a 794 S size 25 needle. 

I increased the top tension and am getting slightly better results, but the stitching seems abnormally tight, like it's sinking too far into the leather. Going to do some more tinkering today.

These heavy duty harness stitchers usually ship with high thread tension and foot pressure because they are typically used to sew hard, dense leather. You will need to dumb down your machine to sew soft leather. Start by backing off the bobbin tension screw until there is just a slight amount of pull required. Next, back off the top tension to balance the knots. Next, back off the top foot pressure screw on top of the right end of the head. Use just enough force to keep the leather from lifting with the threaded needle and the bobbin thread locked around the needle. This setup won't work as well in dense leather, so try to make a mental note about the initial setup tensions and pressures.

Finally, adjust the stitch length a little shorter to minimize the warping of the material.

[Northmount]

42 minutes ago, Klover said:

I haven't adjusted the presser foot at all, but I will definitely take a closer look. I'm using the needle that the machine arrived with. It's a 794 S size 25 needle. 

I increased the top tension and am getting slightly better results, but the stitching seems abnormally tight, like it's sinking too far into the leather. Going to do some more tinkering today.

Google AI "A 794 S needle is a leather point needle. Specifically, the "S" stands for "spear point" or "narrow cross point," which is a cutting point designed to create straight seams in leather and other thick, non-woven materials."

See attached needle / thread size chart that will be handy for you later.  Looks right for your current leather.  If you start using hard dense leather often needs a size larger.

 

 

[Klover]

1 hour ago, Wizcrafts said:

These heavy duty harness stitchers usually ship with high thread tension and foot pressure because they are typically used to sew hard, dense leather. You will need to dumb down your machine to sew soft leather. Start by backing off the bobbin tension screw until there is just a slight amount of pull required. Next, back off the top tension to balance the knots. Next, back off the top foot pressure screw on top of the right end of the head. Use just enough force to keep the leather from lifting with the threaded needle and the bobbin thread locked around the needle. This setup won't work as well in dense leather, so try to make a mental note about the initial setup tensions and pressures.

Finally, adjust the stitch length a little shorter to minimize the warping of the material.

Great info. I will give this a shot! Thank you. 

And thanks to everyone for the input. All of it has been tremendously helpful! Will continue to tinker a little bit.