MC333 - I completely believe the quality control issue you mention. I think that's why most people tell you to use Schmetz, rather than Singer needles, etc. There definitely is a variance in quality, so I try to use Schmetz or Organ when I have them.
The funny part is, I lack a lot on the sewing theory side, and the mechanical quickly passed that knowledge, but I've always worked on cars, motorcycles, bicycles, computers, etc, so it's probably more "natural" for me even though I've been sewing bits and pieces since I was 10, and servicing sewing machines about a year.
Is my theory right with the presser foot tension? Thin materials will have more presser foot tension, just because there's less bulk under the foot, because all we're doing is making sure there's
-just- enough pressure to move the fabric
evenly, and not schmush it as hard as we can. - now that I write it out, it looks wrong to me. Am I mixing pressure with height?
I had not realized the thing with the static.
I will double check the thread path. This one is weird because there is a "groove" (on all of the German machines) as the last guide before the thread leaves the "body" area, and descends toward the needle bar area.
I'll snap a couple of pics too, to see if anyone can spot anything I'm missing.
I have a laptop like that too.
I try to just use a USB keyboard with that one to save my sanity.
Miriam - Is yours always skipping on the right or left side? This one is the right. I suppose I could look at the needlebar. I guess I just thought if it was the NB, that it would manifest more consistent skipping issues. I'll double check the centering and such. There is a section in the Service manual about zeroing things out, maybe now's the time to try that one out. I'm hesitant to raise or lower the NB, just because all 5 of the slants here (4 of them German) look virtually identical for timing. I removed the NB on a featherweight I've got disassembled to paint. I hear ya on the slippery part. I guess that's what happens when we insist on oiling everything.
Joe - Sew-All is supposedly 50wt. I know the test you're talking about, it's how I set these ones up too. but a "barely perceptible tension" is a little subjective, and I think it would vary from day to day depending on a lot of mostly carbon based life-form factors (for instance, I spent several hours on Sunday in the garden and backyard, getting sun burned and sore muscles. I feel everything more acutely than usual today. I think that today's tension adjustment may be different than last week, when I was being a sloth.) I can try using some of the old thread, to see if there's a difference, though. I'm always up for trying something else that will let me keep my hair.
I try to test sew with a couple of different weights (always at least 2 layers though as mentioned above) because you never know what people are going to throw at the machine. I sew everything from light quilt cotton, to nylon webbing for the dog's harnesses. I don't want it skipping stitches when I'm using it, because when I'm using it, I'm not usually in the mood to be servicing at the same time.
The needle though would drop the same distance with or without fabric. It's not dependent on anything under the presser foot to determine height. I can see how less resistance from a thin single layer of fabric may make the loop form differently than with a thicker stack of fabric.