Minimum Sewable Thicknesses

[amuckart]

There's a lot of discussion on here about the maximum thickness various machines will sew. Something I'm trying to work out is what the practical minimum thickness a threaded-needle machine will sew well without major adjustments (i.e, not more than top/bottom tension).

I'm interested in the general case, if such a thing is possible to establish, but the specific case is whether for someone who is space constrained, a 441 clone will go down the scale far enough to do most of the same kinds of jobs with belts etc as my flat-bed STH-8 will (same as a Consew 206). I'm unlikely to be sewing anything smaller than, say, 69 thread

Thanks.

[dbusarow]

I have used my Cobra Class 4 to sew 2/3 lamb lining onto 4/5 veg-tan using 138 thread and a #21 needle. This was for a rolled edge on a woman's wallet so the real thing had the wallet liner inside as well but I did my adjustments and some practice pieces with just the two pieces of leather.

All I had to do was back off both top thread tensioners quite a bit. Other than that nothing to it and the stitches were beautiful.

Dan

[Wizcrafts]

My buddy has a Cobra Class 4 and he has had me alter leather garments and install new zippers on it. Using #69 bonded nylon thread, I changed the needle to a #19 (I'd prefer an 18) LR point, then loosened the upper tension until the knob almost spun freely - and sewed two layers of 2 ounce lambskin or thin garment cowhide. The bobbin thread was already very loose because the case spring was tensioned for thicker thread.

Having a light pull on the bobbin is important when you sew thin garments. Any appreciable drag will cause the stitches to pucker the soft leather on the bottom.

This same setup was also used to sew a cloth bag at the seams.

The biggest issue is the length of the needles. At over 2.75 inches they are easy to deflect and bend or break, if they hit any thick seams - not dead on. This happens mostly when I install zippers and have to walk over a couple layers that are folded together along the front sides. I try to slow to less than 1 stitch per second as I sew these very short raised layers, then let her rip on the level areas.

I almost forgot to mention that if the top pressure adjuster is down any appreciable distance, you might need to back it off until it almost pops out. This is when sewing thin or soft temper leather or webbing or cloth.

[amuckart]

Thank you both.