I have successfully sewn leather with a teflon foot. It is important to pin frequently so that the two layers do not slip. Be sure that you are using strong thread. Do not use a small stitch as you can cut the leather. If you have one of the stretch stitches on your machine, I would use it.

Teflon feet work when you're sewing from the slick side. Don't pin because the holes will stay there. Use the black office clips or clothes pins. A walking foot is recommened in lots of intructions because it feeds the top layer as your feed dog feeds the bottom layer. I don't see where a stretch stitch would help. They make several back & forth stitches in the same spot....preforating your leather that much more. If you use the same thread on top & the bobbin, your bobbin case made need adjusting. This is not an adjustment you may wan't to do because they are usually factory set. Some people buy & extra to use on unusual projects.

What are you attempting to make?

I have very strong thread, it's 100% nylon and I've had no problems with it breaking...I can't break it by hand. It's upholstery thread, I believe.

I read somewhere that you can/should use longer stitches for thicker material...I was using one of the longer settings and it seemed to be doing okay.

I have had trouble with the material moving through the foot. The presser foot pushes too hard sometimes because the material is so thick. I'm not familiar enough with sewing and/or my machine to know anything about a walking foot, but I'll google that and see what I find out.

My bobbin case hasn't been adjusted, but it seems to be doing okay.

Sometimes the needle can't pierce the leather if I use the pedal, and I have to rotate the knob by hand. Still about twenty times faster than hand stitching...

I'm attempting to make a pool cue case, so it involves some stitching and a lot of other stuff. I didn't think the stitching would be as important and difficult as it has turned out to be.

I can't figure out how to put on my pocket, for instance...

But I'm getting there.

When I sew leather I prefer to use a 'weak' thread. My theory is that if something is going to break, I don't want it to be the leather itself. The easiest example I can think of is the strain that can be placed across the shoulders. For instance the stress at the seam of the back and the sleeve. If the thread is strong the leather will rip but if the thread is weak it will break and the seam can be repaired with care.