Methods of finding center of a worn shaft?

[Cadillac]

So I’ve gone through this exact situation on three chucks I’ve purchased. What I did on one with similiar wear was. Turned the main shaft to clean up then bush the mounting block. Most likely the hole is worn too. Then the small shaft you can see a spot that isn’t worn that’s your diameter. I bored it out then pressed a pin. Remake the linkage bar to your pin sizes all done.
I noticed you wrote the pin diameter as .312 then your linkage holes should be .313ish not both .376. That all your throw right there.
The magnet works by the offset of that main rod and the linkage piece putting the magnets in the correct spot. Same with demagnetizing the chuck.

 

[mac1911]

So I’ve gone through this exact situation on three chucks I’ve purchased. What I did on one with similiar wear was. Turned the main shaft to clean up then bush the mounting block. Most likely the hole is worn too. Then the small shaft you can see a spot that isn’t worn that’s your diameter. I bored it out then pressed a pin. Remake the linkage bar to your pin sizes all done.
I noticed you wrote the pin diameter as .312 then your linkage holes should be .313ish not both .376. That all your throw right there.
The magnet works by the offset of that main rod and the linkage piece putting the magnets in the correct spot. Same with demagnetizing the chuck.

Seemed a little odd both are .376 and nice and round.?
I can measure the amount of throw or lack of it that keeps the plates from lining up 100%
Just because I need experience on the lathe more than a magnetic chuck at the moment.

 

[Cadillac]

The eccentric of that control rod is the distance between the magnets what’s the size of the pin on the magnet? .375

 

[mac1911]

The eccentric of that control rod is the distance between the magnets what’s the size of the pin on the magnet? .375

Roughly .125” needed for the plates to line up correctly?
The handle would only move from off to about 120’ when I first got it. Disassembled the chuck and the only thing I found was some hard crusty grease in-between the plates. Once I cleaned all the dry crusties out and lubed everyrhing the handle moved to 180’ swing but you could feel the last 40’ or so was just slop.

 

[stupoty]

https://www.hobby-machinist.com/threads/chuck-adapter-plate-for-my-smithy-1220.109124/page-3

I need to acquire more tools and know how.
Only indicator I have with a small enough tip that might pick up what very little is left of the “good” portion of the shaft does not fit any of the holders I have.
I will get there, I dont have a lot of time to get on the lathe and now the cold has set in ( un heated work area) . Honestly I think I have no more than 15 hours on the lathe for 2023.

I practice setting up parts in the four jaw with a pointer, I can get within a few thou of dead nuts like that.

U can use chalk if you don't have a scribe block pointy thing.

It's handy if your setting up a rough casting or something with very bad surface issues that an indicator wont run on very well.

Stu

 

[mac1911]

Im not the best photog , but you can make out that theres is just a smidge more to go before full line up.
Im going to try and test the holding power as it sits and compare it when I finally get it aligned 100%

 

[mac1911]

I dont have any pictures and did my best to start trying to make a part.
Had to do some work on the cross slide , theres a round block at the back side that keeps drifting out causing a lot of slop in the cross slide screw.