Cobra class 4 tension issues

[jezzell]

Good morning, I am trying to get my new cobra class 4 tensions correct and having the hardest time. The stitching on the top seems good but it's looking like the stitching on the bottom is pulling into the leather. I have decreased the bobbin tension but maybe I'm a little nervous about going to far. Any advise? I can also upload the top side if needed.

 

[DieselTech]

1st off, so everybody is aware. What thread? What size thread? & needle are you using? 

Also what weight of leather? 

Also food for thought, the bottom stitching will never look as good as the top stitching. Or at least I think. 

[jezzell]

9 minutes ago, DieselTech said:

1st off, so everybody is aware. What thread? What size thread? & needle are you using? 

Also what weight of leather? 

Also food for thought, the bottom stitching will never look as good as the top stitching. Or at least I think. 

It is nylon thread, size 277 with 180/24 Schmetz needle. Leather weight is 8.5oz

 

[DieselTech]

1 hour ago, jezzell said:

It is nylon thread, size 277 with 180/24 Schmetz needle. Leather weight is 8.5oz

 

I am a newbie to this sewing machine stuff too. But I am thinking if it is sucking/pulling the thread in deeper on the back side of the leather. That you need to decrease the tension on the top thread. 

Or tighten the bobbin tension to pull the top thread in deeper to the leather. 

Basically I think it can be done both ways, but 1 way might produce better results than the other. 

Edited Monday at 07:49 PM by DieselTech

[Wizcrafts]

@jezzell

First of all, #277 is too thick for 8 ounces of leather. Move down to #207, on top and in the bobbin. Your #24 needles is the right size for #207 thread, not 277. That calls for a #25/200 needle. I you insist on having 277 on top, at least wind a bobbin with #207. Then the #24 needles may work better.

The next issue is the shape of the needle. You seem to be using an S point needle that causes the edges to be pulled into the leather, shortening the appearance. Get you some diamond or tri-point needles. They let the stitches stay on the surface on both ends.

[jezzell]

1 hour ago, Wizcrafts said:

@jezzell

First of all, #277 is to thick for 8 ouces of leather. Move down to #207, on top and in the bobbin. Your #24 needles is the right size for #207 thread, not 277. That calls for a #25/200 needle. I you insist on having 277 on top, at least wind a bobbin with #207. Then the #24 needles may work better.

The next issue is the shape of the needle. You seem to be using an S point needle that causes the edges to be pulled into the leather, shortening the appearance. Get you some diamond or tri-point needles. They let the stitches stay on the surface on both ends.

@Wizcrafts

Thanks for the info, I read the wrong number on my Guage it is 22oz leather thickness and yes they are S needles. I will need to source some diamond point needs. To be clear on the stitch, would the S needle only have the edges pulled in? Attached is an image of the same stitch but it's the opposite side.

Thanks for the advice.

[PeterinID]

When the machine pushes the needle through the leather the leather must move to make room for the needle and the leather gets displaced downward along the needle path, this creates the bottom side bulging you see. This phenomenon exists with all machine stitching to some degree and thread size, needle size, needle tip leather thickness and tannage are all factors that can increase or decrease the phenomenon.