I need help on sewing with my cobra class 4

[Double S leather]

when im sewing on my cobra class 4 it sucks some stitches down really tight to where you cant see them but they all seem to be way to tight just would like some advice please

[Cattledude]

Just a thought… make sure the thread is spooling even from the stand to your machine and the center of the spool is directly under the thread stand guide.

[Hildebrand]

I would start by lengthening the stitches out(decreasing the stitches per inch) so you can easier see what you have going on, then use different color top and bottom thread then you can see if the knot is pulling to the top or the bottom.  Just guessing from the picture, because it appears stitches are missing which I assume got pulled through.  This is usually too much bobbin tension but the very short stitch length can contribute to pulling through as well.  

[Tigweldor]

I would second that.

If your bobbin holder tension spring was set up for say 69 thread and as a whim of notion you now decide to run 138 thread - bobbin tension will all of a sudden be way to tight.

You should always try out your stitch setting on a piece of scrap leather with exact material and thickness that your project is - before sewing your end-product.

Doing that will save you a lot a hassle in the long run.

Using different colour thread as Hildebrand suggested, is a very good way to diagnose/tune settings.

As you get more experienced - you can check bobbin thread tension by just pulling on the bobbin thread by hand.

Now there is no way to describe it properly - it is a "feel" that comes with prolonged use of your machine.

In the industry they do use thread tension scales - I bought a pair once years ago, but have never used them - one of those "gizzmos" that you do not really need for single needle sewing machines.

On twin or more needle machines this is a different story, as you want all threads with exact equal tension.

Greetings

Hans

Edited yesterday at 07:23 PM by Tigweldor