Bubble Marks On Backside Of Leather - Feeddogs.

[efaz]

Hi everyone!

I'm having an issue with my new compound, lockstitch, cylinder arm sewing machine. When I sew semi-anline or aniline dyed leather the backside leaves marks as shown in the picture (2 pieces of 2mm bridle shoulder). It doesn't do this on chrome tanned leather. Is this normal?

Thanks!

Elisa

[TwinOaks]

It's the result of a combination of the pressure of the presser foot, the firmness of the leather, and the size of the needle. Basically, the leather is being pushed into the little hole where the needle goes into the arm. You can lighten the presser foot a bit to see if it helps....or you could just hammer the threads down if everything on the machine is sewing well.

[efaz]

I've tried hammering, but the marks are still there. the leather is very firm - bridle shoulder. This doesn't happen with chrome tan, only with semi-aniline finishes. I am using a 140 size needle. I will try to lighten the presser foot and report back.

Thanks!

[pcox]

what size needle and tread are you useing? Tread looks a little big for that thickness. What point on the needle? I think smaller needle/tread combo with a leather point might pierce the material easier and not push the leather into the needle plate hole.

[efaz]

Hi! The thread is size 30 and the needle is a 135x17, size 140. It is pretty dense leather (Bridle shoulder). I tried reducing the tension at the top and it worked a little. I'm going to see the engineer this weekend.

[pcox]

did you mean 14 instead of 140? a 140 is a 22 way to big for 30. a smaller hole it your needle plate may help also

[efaz]

Thanks, pcox.

It is a size 22. I am using a size 30 bonded nylon thread (UK) I'm not sure what the conversion is, but I know that it is pretty thick and fits with the needle.