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Sewing Machine Modifications
S. Heslop:
Thanks!
I'm still fussing about how to try extending this. I've also measured the shafts and found them to be some fairly bizarre sizes that don't really line up with anything, in metric or imperial. The one shaft I was hoping to fully replace is around 0.370" and I can't see myself turning a long bar down successfully on my little lathe, but I can see myself maybe getting an adjustable reamer to work in making an extension. Even if that's not a great solution.
This is just starting to feel incredibly kludged before i've even made a cut. But I'll give it another day of thought before I just slice the thing in twain and work from there.
S. Heslop:
In tapping the front bearing block out with a screwdriver i've gone and peened it enough that it wont come off the shaft. I didn't think I was hitting it that hard but I should've gotten the brass bar out sooner. I should also add that I'm planning to exend it out 5 inches, which is a fairly considerable span. I'm worried mostly about vibrations.
I'm picking my brother up from work tomorrow. Might ask his thoughts on welding cast iron. With that bearing block damaged I'm considering making an undersized replacement, with maybe a millimeter gap around it in the bore. But floating it in with epoxy/ epoxy putty. Alot of the stuff in the actual head itself beyond that is a somewhat loose fit so I think i'd have some room for a little misalignment.
mattinker:
--- Quote from: S. Heslop on March 24, 2019, 10:03:55 AM ---I can't see myself turning a long bar down successfully on my little lathe,
--- End quote ---
Simon,
couldn't you just turn down the ends where it counts?
Fun project, regards, Matthew
WeldingRod:
I would avoid welding it!
Sneaky idea: clean both side around you cut line, and mould steel filled epoxy surfaces. Ideally use some setscrews and screws to get flat plates positioned parallel to the machine shafts. Drilling and tapping holes on both sides is worth the effort, and will help keep the epoxy in place. And, cast in alignment key slots. Then cut it in half.
That way you have true surfaces to work off of after cutting. Think in terms of bedding an action, if you speak gunsmithing...
Of, and dont forget mould release on the plates you cast against...
Sent from my SAMSUNG-SM-G891A using Tapatalk
S. Heslop:
--- Quote from: mattinker on March 24, 2019, 11:09:08 AM ---Simon,
couldn't you just turn down the ends where it counts?
Fun project, regards, Matthew
--- End quote ---
Good call! Thanks.
--- Quote from: WeldingRod on March 24, 2019, 12:44:58 PM ---I would avoid welding it!
Sneaky idea: clean both side around you cut line, and mould steel filled epoxy surfaces. Ideally use some setscrews and screws to get flat plates positioned parallel to the machine shafts. Drilling and tapping holes on both sides is worth the effort, and will help keep the epoxy in place. And, cast in alignment key slots. Then cut it in half.
That way you have true surfaces to work off of after cutting. Think in terms of bedding an action, if you speak gunsmithing...
Of, and dont forget mould release on the plates you cast against...
Sent from my SAMSUNG-SM-G891A using Tapatalk
--- End quote ---
Yeah trying to weld it doesn't seem like the best idea. I keep going back and forth on it though.
The trouble i've got is that i'm fairly under-equipped for making any accurate measurements or jigging it up well. The top of the casting though is sort of flat, except for the protrusons, so I might be able to work from that. Cut the thing in half, screw some precision angle iron onto the rear side into the top edge, then slide the front end about till the shaft spins freely and fix that with screws and epoxy.
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