503 tension problem
 

At the last minute they called and said I needed to take another machine to school and none of my spares were ready to go. So, I took my 503. It's a cabinet machine, not a portable, and I took it bare, without a case as it wouldn't fit in the only case I had. I can't remember for sure, but I think it fell over in the car.

Before it went for the ride, it was sewing just fine. (I double checked what I had been working on and it looked good.) Not so, today. I can't get the top tension to tighten up enough. If I turn it all the way down, it is still bumpy on the bottom side. It's a double needle machine, so it has two options for the thread path. I tried both. I've threaded and rethreaded it, but that's not the problem. You can feel when you pull the thread on the needle side of the tension that it's loose.

I've watched a couple of youtube videos on tension, but they don't seem to address this kind of problem.

Any idea where to start?

bkay

I wonder if the tension release mechanism got out-of-wack. When you lift the presser foot, do the tension disks go loose? And do the tension disks go tight when you drop the presser foot? You can open the left side door and watch what happens to the back of the tensioner. There's a little post that should be pushed when the presser foot goes up.

Yes, the tension release mechanism is still in place. The spring is still attached and the thingy still touches that little post. The tension mechanism moves when you drop and pick up the presser foot. There is a slight difference in the thread tension when you drop and raise the presser foot, just like there is when you move the dial on the tension from lowest to highest. However, it's still really loose.
bkay

I found a 500 service manual in my download files. (Tension page below.) What's happening is that the thread comes out of the take up spring when you start to sew.

Screw C is is further to the left in slack thread regulator D than is specified in the manual. It says 1/16 to 3/32. Measuring with a hem gauge, it appears to be about an 1/8, which if my grade school math is correct is 4/32. Could that be the problem?

(I'm definitely not an experienced person at mechanics, so I don't want to mess up something worse than it already is.)

bkay

Same machine, similar problem
 

I posted this several months ago. Somehow, this magically resolved itself. I went back to the machine and it worked correctly. If I fixed it, I don't know how. I've been using this machine since.

Yesterday, I changed the cam in it. It has always had the regular zig-zag cam in it. I've used it a few times and it worked just fine. I couldn't get the other cam to work correctly, so I decided to do something else. I put the zig-zag cam back and adjusted the tension to work with it. The tension was too lose and the stitch length too short, so I adjusted it again. I got busy trying to figure out how to mount the ruffler attachment and didn't sew anything.

One of the neighborhood kids wanted me to repair his jacket, so I took the ruffler off and started to work on his jacket. The stitches wouldn't work. So, I got out some scrap and started to test. It skipped stitches, spaced stitches unevenly, broke the thread, left pieces of thread in the bobbin area and left loops on the bottom, like the tension was loose. I re-threaded it repeatedly, changed the needle, changed the tension, changed the thread and changed the bobbin several times. I even got a bobbin from my 201 that I knew was vintage. All those actions changed and improved things, but did not solve the problems.

Finally, I watched and listened very carefully. It's not sewing exactly straight. The needle will occasionally zip a tiny bit to the left. After about and inch or so, the bobbin area starts to rattle. It's not loose, though.

Any ideas where to start? Any help would be appreciated.

The square sample is where I started. The rectangle was where I quit.

bkay

Have you taken the needleplate off and the bobbin race out? Sometimes there will be a wad of dust or a thread piece wrapped up inside and behind. Also, have you oiled it everywhere needed, including underneath? You could also have a gob of dried up oil in there somewhere. It could've moved at one point, making it easier to sew, then gotten stuck again.

I'm betting on a loose piece of thread wrapped behind the bobbin carrier, just because it's happened to me before!

When no one answered my question, I posted on the slant singer group on Yahoo. They suggested a good cleaning and oiling, which I am doing. Now I just need to get the whole thing back together.

I probably need to clean the tension, but I'm not going there unless I have to.

Thanks, Margaret.

bkay

If the bottom picture is the top of the fabric, there's no tension on the bobbin case. Have you tightened the bobbin case tension?

Does it zip to the left while the needle is still in the fabric? That would mean the parabola is off. I'm not very familiar with the older Singers, but on most mechanical machines, that comes from the worm gear on the top shaft.

Quite often you will get a leftward drift at the end of a seam, which can be cured with a good stiletto and sharp attention. I have to go back and re-sew the ends of my seams all too often! Dirt, fuzz, and oil globs will also cause this kind of problem, so your cleaning and oiling may fix the problem. I used to have a Kenmore that drifted left constantly. That may have been the worm gear, but I'm still not far along enough to know how to check that! Good luck, bkay!

PS - run a strong thread or use a stiff brush under your bobbin spring. I had one with just a large speck of dust in it that created havoc!

Thanks for all your help. I solved the problem. I've thoroughly cleaned and oiled all the parts I can without taking it apart. (I thought I had already done this machine, but obviously, not.) It's running much smoother and seemingly quicker.

I'm sure it helped that I turned the needle around, too.

Thanks again for your help.

bkay