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Missing something simple - skipped stitches

Missing something simple - skipped stitches

Old 05-06-2013, 11:24 PM
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Default Missing something simple - skipped stitches

So on almost every Slant-o-matic I've had here, I've had this problem at some point. This week, it's on a Singer 431G (basically the lock stitch and chain stitch capable, open arm, German cousin of the 401A)

Test sewing on a "regular" quilting cotton or similar thickness (or lighter) other cotton, or cotton poly, 2 layers, no batting.
  • The straight stitch is beautiful and no problems whatsoever. Tension well balanced right out of the gate.
  • The zig zag stitch, or other decorative stitches will skip the occasional stitch, always on the same side.
  • If I go to a thicker fabric, or fold the cotton so I have 4 layers, I have absolutely no problems.
  • This occurs with or without upper tension adjustments when changing fabrics.

What I've done so far:

  • All tests are done using a Gutermann Sew-All thread top and bottom, with a new Universal 90/14 Schmetz needle. (I may have also tried an 80/12 quilting needle, but it's a little dim, because it was a few days ago)
  • I'm reasonably sure that the tension is right or at least equally balanced. i.e. they both could be a smidgen too tight or both a smidgen too loose.
  • The machine has been fully serviced and oiled, both tensioners disassembled and cleaned and set back to the recommended setting per the Singer Adjuster's manual
  • timing has been checked again and again. It's right as best I can tell ( the hook point is never -exactly- behind the needle at the mark on the needleshaft, it's usually a smidgen advanced, but no matter how I mesh the gears, I can't get it bang on. Also, all 5 of the Slants I have here have exactly the same timing, and I've only timed two of them - one that I changed the hook on (which sews beautifully now), and one that I should change the hook on, but filed the "curled burr from a needle strike" off the tip of the hook instead, because the hook that machine uses is rarer than gold plated diamond encrusted hen's teeth. )

I have never truly learned the presser foot tension rule, I generally just "futz" til it works, so my poor little brain feels like there's something there that's missing.

I can't help but think it's more sewing theory I'm missing, than something "wrong" with the machine.

Of course, I really want to hear other things I can try
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Old 05-07-2013, 01:06 AM
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It comes down to timing. I've heard that there is a "timing error" or something associated w/ needle swing for the zz stitch, and that exacerbates the skipped stitches occurring on zz vs. straight stitches.

There seems to be a lot of problem with this, across the board, on all zig zag machines. That makes me think it's some sloppy quality control on the needles or the threads or both. Your mechanic skills are more advanced than mine, but I'll give it a shot.

What I have seen suggested:
  • Adjust the timing on machines, which you did.
  • Try different brand of needle or type of because there seem to be slight differences in the length that can make one brand work better or worse on any given machine. (Needle length "just right" = good timing vs. "timing is off.") And also the piercing power of a needles and machines varies, so you have to "mate" those two things so that the there's not a delay in when the thread loop being formed.
  • Try a small or a larger needle. Sometimes the opposite of what you expect works.
  • Fabric feeding rate has to be right: Adjust presser bar pressure to keep fabric from rising up. Or loosen it, just for giggles.
  • Change the brand of thread. Or go thicker or thinner.
  • Use silicone spray or Sewer's Aid on the needle to make it slicker.
  • Spray thread with Static Guard b/c some threads apparently either develop static electricity or heat (they melt going through the needle?), and then the thread drags, and throws off the timing of the loop enough to mess with the stitches.
  • Keep lint out of the tension assembly and bobbin case.
  • Thread delivery system, too. Inspect the front of the machine for work parts or a burr or notch in the actual front side and the edge of the machine where the thread descends toward the needle. Some machines wind up with a groove carved in them from years of use. Someone said bend the thread guides a bit so they stand out enough to keep the thread up off the surface of the machine worked.

Last edited by MadCow333; 05-07-2013 at 01:12 AM.
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Old 05-07-2013, 02:14 AM
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I'm having problems with skipped stitches with a 'newer' Singer - I've racked my pea brain trying to figure it out on my own... it only skips when it trying to do zz and only on one side. Makes me think the timing is off slightly. If you can't change it from the gear end maybe you can change the needle bar just a little. Is it centered? Is the needle bar bent just a little? About the only way to tell if one is bent is to pull it out and look at it unless it is obviously bent a lot. I had a 411 give me fits until I pulled out the needle bar and tried rolling it across the table. Once you learn how to put it back it isn't a bad job. The first time I did one I was shaking like a leaf and I had my sister there to observe. Best to make marks - that needle bar is slippery.

Last edited by miriam; 05-07-2013 at 02:30 AM.
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Old 05-07-2013, 04:12 AM
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When I set the tensions on my older machines I use Size 50 thread. I have several Singers and other brands that actually state in the manual to use that size thread when adjusting the tension. The thread I use is not the new stuff, but the old stuff from when the machines were made. There is a difference. It's my experiance that once the tensions are set with the old Size 50 thread, my machines are much less picky with the modern stuff.

On the ZZ machines that skip stitches on only one side I've usually found the needle is not centered in the needle slot on SS so when on ZZ the swing is more to one side than to the other. When centered the skipping is greatly reduced or eliminated. I've got a couple I had to do that with.

I also always use a thick material such as denim or at least a double layer. Seriously, how often do we really sew single layers of fabric? Almost never when making things. Even when I do a pattern test on my ZZ or cam machines I use a double layer or a thick fabric. It's my thinking that with one layer of normal cotton or similar, the needle drops down just a teensy bit too far and doesn't always catch the thread on the way back up.

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Old 05-07-2013, 04:36 AM
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I tested multiple layers of various fabrics. I don't know how the needle could be any more centered unless the needle bar is slightly off.
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Old 05-07-2013, 05:03 AM
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Hmmmmm, perhaps that machine was just being contrary? I've got a couple like that. Darn things.

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Old 05-07-2013, 06:49 AM
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inspect the front of the machine for work parts
Should say worn parts. I have one laptop with an abysmal keyboard, and that's what I was typing on when I wrote that post. Plus I had a cat trying to lie in the keyboard at the same time.
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Old 05-07-2013, 11:09 AM
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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.
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Old 05-07-2013, 12:03 PM
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I had a White I worked on briefly today. It skipped stitches until I put in a new needle. And usually a new needle or different thread will change things. The Singer I have that skips only on zz does it only on one side. ss is ok - I didn't get a chance to really look at it today. You can bet I will when I get a chance. Kidos showed up and we just made mudpies and cut hair.
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Old 05-07-2013, 09:16 PM
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*mumble mumble mumble* I lost a whole day fighting this machine. I timed it again, I just wasn't happy with the stitching, and wanted to rule it out for sure. No change, so I guess that's good, it wasn't wrong before.

  • I tried Joe's old thread to set the tension. Tried to sew a strip to see what would happen. skipped even on the straight stitches on heavy fabric. Hmmm.. something's not right. It's going to be a long day, I can tell.
  • Went back to the Gutermann.
  • Looked at the thread path, the top guide (first one after the thread) was bent a little. Fixed that.
  • Felt like the return spring on the tensioner was too loose, so rejigged that.
  • Fiddled around a little with the position bracket, tried to get it to fit more like the one on the 411G, possible small success there.
  • Tried 80/12 Quilting needles, 90/14 Universal, 90/14 topstitch.
  • The 90/14 universal did the best on the heavy fabric - no skipping, the 80 and the topstitch needle both skipped something fierce. Interestingly, the TS needle skipped on both sides.
  • Tightened tension, loosened tension. Tightened presser foot tension, loosened it.
  • Checked and changed the bobbin case tension.
  • The needlebar looks like one screw and a little convincing. Does that sound right? I may look at it,.. uh probably thursday now.
  • The needle is maybe a žmm off on the left. Which is about 0.00984249 of an inch... it throws further to the right than the left.
  • Didn't have any of the sprays, so I didn't do that today.
  • I figured out that it skips stitches a heck of a lot less if I hand turn the machine.
  • It never skips if I take the bobincase out (i.e. the hook grabs the thread everytime)
  • the point of the hook in this machine looks ever so slightly longer than the other 4 that work (apparently there are 5 german Singers here, I lost track, much to DH's amusement) but carries the same part number - possible revision? The longer one is the older hook.

Thursday, I think I'll try Cotton thread, just to see if there's a better result. I don't believe in "My Machine doesn't like X brand of thread "on a well setup, serviced oiled and adjusted machine that has its tension is adjusted appropriately for the thread, but maybe I just met "that" machine.

Thoughts? This one is really beating me up so far.
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