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Singer 15 & Clones: Tension Mechanism Assembly

Posted by Janet Szabo on

Reprinted from Suck It Up, Buttercup

I wasn't going to blog about this machine, but I started working on and ran into something interesting. In the spirit of helping my fellow amateur sewing machine mechanics to NOT have to reinvent the wheel, I am posting this here. 

Back at the end of April, I went over to Spokane and this little beauty jumped into the back of the station wagon:

The picture doesn't do justice to the lovely shade of turquoise. And it looked like it hadn't been used much, just stored somewhere very dusty. This is what is known as a "clone," or a knockoff of the Singer model 15. You can tell that because the tension assembly is on the face plate. (You can't see the tension assembly in this pic; that black knob turns the light on and off.) I can take apart and reassemble clones pretty much blindfolded now because I have done so many of them, but this machine had a few quirks.  

I always love to see stuff like this:

I think someone tried to run the machine to see if it worked. The belt was distintegrating, though, and all of this gunk ended up in the motor. Belts and bobbin tires are notorious for this kind of stuff. 

I cleaned all of this out of there and then turned my attention to the machine. It really didn't need a lot of work, just a good polishing. When I went to put it back together, though, I found myself with several extra washers. I eventually figured out where they went (the husband helped). The tension assembly, though, is where things got interesting. At first glance, the tension assembly looked like the kind on a Singer Featherweight. No biggie. I've taken those apart, too, and put them back together, and there are plenty of exploded diagrams on the web if I get stuck. I blithely took the tension assembly apart and dunked all the pieces in an OxiClean/dish soap bath. 

Reassembling the tension has to happen in a very specific set of steps. Leave one out and you have to start over. It begins with this piece. That pin in the end of the shaft is what controls the tension disks and thus the tension of the thread as you sew. See those tiny grooves in the shaft? There is a thread check spring with an elongated end that fits into one of those grooves to hold the spring in place. 

I was trying to hold these pieces and take pictures at the same time, and this one came out blurrier than I wanted. I think you can see, though, the end of the spring tucked into the groove at about 10 o'clock. 

That pin—inside the shaft—and the spring slide into this collar, which itself slides into the tension housing on the faceplate. Here is the collar, partially inserted. 

Looking at it face on, you can see that there is a cutout in the collar that matches the cutout in the housing, from about 1 o'clock to 4 o'clock or so. This is where the check spring will ride back and forth. The purpose of that check spring is to maintain tension on the thread as the takeup lever moves up and down and pulls thread through the machine. 

There are two screws here. The one on the left is a set screw (only partially screwed in here) that holds the shaft in place. The hole is for the other screw that controls the position of that metal collar; it can be moved back and forth in that channel to adjust the check spring, if needed. 

Here are the metal collar and the shaft with the pin locked into place, and the check spring is also where it needs to be. From this point on, the tension assembly gets put back together by sliding parts onto the shaft. 

The first piece is the thread guard. If you forget how which way it slides on, just look for the little tongue at about 7 o'clock; it slides into a corresponding cutout in the housing. 

The two tension disks slide on next. I am sorry, but I forgot to get a picture of them. They fit with their convex sides facing each other, so they should look something like this when they are in place:  )( 

Here is where it got interesting. I looked at the assembly and I was pretty sure that a washer went on next. There is a piece that has a -|+ symbol on it so you know which way to turn the knob to increase or decrease the tension. Something has to keep that piece from rotating; in other words, the piece with the -|+ symbol needs to be locked in place. In my haste to disassemble the tension assembly—because it looked like others I have worked on—I neglected to notice that there were two washers and to remember which one went where. (Hence this blog post, because I can guarantee that someone else out there will do exactly the same thing.)

The washer on the left really wasn't made to fit the piece that needed to stay in place, but the washer on the right looked more like the one that I am used to seeing that goes on a little bit further down the reassembly line. Hmmm. I looked at the Piece That Should Not Move:

The washer on the right looked appropriate, so on it went, followed by the piece shown above. Indeed, the washer snugged right in and kept the -|+ from moving back and forth. 

Next to go on is this piece, known as the beehive spring for obvious reasons:

This piece slides on so that the rounded piece sits at the bottom, like a "D" on its side. It is followed by that other washer, but here is where I got really confused. On the Featherweight tension assembly, which this assembly resembles (sort of), the washer sits with the little finger poking forward to catch the part of the tension assembly with the numbers on it. Clearly that was not going to work, because the finger on this one was too big. Thankfully, I ran across this blog post on the My Sewing Machine Obsession website. This lady's clone has an identical tension assembly, and she was able to figure out that the little finger needs to face inward, like this: 

The numbered dial slides on next. I didn't get it positioned correctly the first time, so I had to adjust it a bit so that when it was all the way out, it read "0" and when it was all the way in it read "9." For normal sewing, it should sit at 4 or 5. 

Finally, I screwed the knob back on to hold the whole works in place. This is what it looks like put back together:

The machine got a new belt, some new spool felts, and a new plug on the end of the power cord (because I wasn't going to plug it in with the existing one on there). We're about to put her back into the cabinet. Tomorrow I will thread her up and see how she sews. These clones are such awesome straight stitching machines. I expect she'll sew beautifully. Her new owner is coming to pick her up on Sunday afternoon.



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  • Bless you!!! I started to panic after I took my tension apart and found your blog! Love it

    Jenna on

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