Singer 108WSV36

[friquant]

23 minutes ago, brongle said:

I tried with some fine lapping compound that I found and it did the trick! The bobbin case no longer binds. It was previously binding with and without the hook gib fully attached, regardless of its position, and so on. I suspect this is one of the issues that the previous owner didn't want to deal with 😅 Fine by me!

Love it when a machine turns freely. The word I heard about lapping compound embedding in the metal was in the context of working with brass (saxophone key rods and linkages), which are a lot softer than these cast steel pieces in sewing machines. I have some lapping compound around here somewhere, looking forward to trying it out on something. Glad you have it spinning nicely.

 

26 minutes ago, brongle said:

I haven't installed that belt quite yet because I haven't gotten the rear bushing out of the machine - I think I'm gonna need to find a 3 jaw puller to get it the rest of the way out, as it's quite stuck right now.

Is it hanging up on the machine's cast body or on the arm shaft? Any set screws holding it to the machine body? Already soaked with diesel? I'm wondering how you could press on the machine body to get it out. The 3-jaw puller I have pulls on the outside and presses in the center, but I don't think pressing against the arm shaft is the right option, unless the arm shaft is actually what it's binding on.

 

26 minutes ago, brongle said:

 I am a bit concerned that the belt I printed won't be quite flexible enough to install through gap once I get the bushing out (per the manual's instructions), but I've got a significantly more flexible TPU in the same durometer that I can try if I can't squeeze it in. 

Had to wrap my head around flexibility vs durometer of TPU. I think I got it now. It wasn't obvious at first that you are pressing tightly against the belt to get it to conform to the cog. 

Gluing a belt (perhaps cut at an angle) has the potential boon of wrapping it around the arm shaft before gluing. I see you've got some good options going here already, but I wonder if TPU could be fused with a hot knife the same way PU belts are fused.

[brongle]

10 minutes ago, friquant said:

Love it when a machine turns freely. The word I heard about lapping compound embedding in the metal was in the context of working with brass (saxophone key rods and linkages), which are a lot softer than these cast steel pieces in sewing machines. I have some lapping compound around here somewhere, looking forward to trying it out on something. Glad you have it spinning nicely.

That was definitely on my mind! They do make lapping compounds for softer materials that won't embed abrasive, usually garnet-based from what I can tell. But yeah, steel parts aren't a huge concern in that regard. This was just generic automotive valve lapping compound, though I do have diamond compound in various grits and a few different stick compounds too. It's actually not something I reach for all that often, mostly because I often forget it's an option 😂

10 minutes ago, friquant said:

Is it hanging up on the machine's cast body or on the arm shaft? Any set screws holding it to the machine body? Already soaked with diesel? I'm wondering how you could press on the machine body to get it out. The 3-jaw puller I have pulls on the outside and presses in the center, but I don't think pressing against the arm shaft is the right option, unless the arm shaft is actually what it's binding on.

I'm pretty sure it's hanging up on the cast body, but it's hard to tell. I removed the one set screw that holds it in place. It looks like a previous attempt to remove it involved a flathead screwdriver used as a drift punch against the inside end face of it, which probably swaged it a little larger and out of round on that end. I agree that it's not ideal to push on the shaft.

Unfortunately the inside of the groove on top is quite rounded off and smooth (like, full radius on the ends), and also full of oil because that's where some felt packing sits for lubrication. The setscrew groove on the back side is not really accessible in this position, and I don't think it has an edge that I could pry on anyway. And, just to clarify, not all of those dings on the bushing are from my removal attempts 😅

 

I could see making a U shaped collar that slides into that groove and uses a few jackscrews around the perimeter to press against the casting. If I can find some time to make one, that's probably a better option than a jaw puller. Might try a print first, in case I can get away with it. 

 

10 minutes ago, friquant said:

Had to wrap my head around flexibility vs durometer of TPU. I think I got it now. It wasn't obvious at first that you are pressing tightly against the belt to get it to conform to the cog. 

Gluing a belt (perhaps cut at an angle) has the potential boon of wrapping it around the arm shaft before gluing. I see you've got some good options going here already, but I wonder if TPU could be fused with a hot knife the same way PU belts are fused.

Yeah, I was thrown off by the same distinction too, to the point that I went out and bought a durometer to check! Turns out both filaments were within a couple points of each other, which is pretty negligible, but one is quite stiff and the other is very floppy. Durometer is just a measure of hardness, and doesn't directly correlate with flexural stiffness, but that isn't immediately obvious. If you think about it in terms of metals, hardening steel doesn't change the way it bends, although some alloys might stress crack more easily when hard. It only changes how much it dents or otherwise deforms locally. 

I bet it could be fused like that! That's an interesting idea. Since there's no tensioner in this machine, it might not be very easy to weld it together in a reliable way since it needs to be connected under slight tension, but I could see that approach being quite useful for other applications. I could also see printing a small strap as a reinforcement for the joint, maybe with some holes in it that engage with bosses on the outside of the belt to keep everything together while you weld it. You could even heat stake the bosses down as extra retention... Might be a good option if I can't get this one in otherwise.

[friquant]

18 hours ago, brongle said:

I'm pretty sure it's hanging up on the cast body, but it's hard to tell.

If the arm shaft still turns freely (or even not freely) I think we can assume it's hanging up on the cast body.

 

18 hours ago, brongle said:

Since there's no tensioner in this machine, it might not be very easy to weld it together in a reliable way since it needs to be connected under slight tension

I don't think the fusing would need to happen under tension. Like the belt could be wrapped around the arm shaft with most of the belt hanging out the top of the machine. Then after fusing it could be pulled down through the body and slipped around the lower cog. I suppose there is opportunity to change the belt circumference during fusing, which would not be ideal.

 

18 hours ago, brongle said:

I could see making a U shaped collar that slides into that groove and uses a few jackscrews around the perimeter to press against the casting. If I can find some time to make one, that's probably a better option than a jaw puller. Might try a print first, in case I can get away with it. 

Would it be fruitful to machine some flats to that bushing? Then you could rock the bushing back and forth with a large spanner wrench while you pry it out. Not sure how much effort that is. My first thought was to twist the bushing with channel locks but that would mar the beautiful finish, and might not be enough torque to rotate it.

[brongle]

On 3/10/2026 at 10:45 AM, friquant said:

I don't think the fusing would need to happen under tension. Like the belt could be wrapped around the arm shaft with most of the belt hanging out the top of the machine. Then after fusing it could be pulled down through the body and slipped around the lower cog. I suppose there is opportunity to change the belt circumference during fusing, which would not be ideal.

That's a good point! Didn't think about doing it that way. I'd be a little concerned about that joint failing over time with printed TPU, but I'm not sure if that's an actual concern or just my imagination.

 

On 3/10/2026 at 10:45 AM, friquant said:

Would it be fruitful to machine some flats to that bushing? Then you could rock the bushing back and forth with a large spanner wrench while you pry it out. Not sure how much effort that is. My first thought was to twist the bushing with channel locks but that would mar the beautiful finish, and might not be enough torque to rotate it.

That's a possibility, but I'd have to get the whole machine onto the mill somehow, and that doesn't seem like a great time... I might have an opportunity to draw up the tool I described this weekend, and I'll try out a printed one as soon as it's done.

I, uh, picked up a new toy rather spontaneously today that I'll post in my Member Gallery thread, so that may pull me away from the less-fun parts of this project for a bit 😅