Methods of finding center of a worn shaft?

OTmachine said:
Looked at your other post. Do you have a lathe with a 4 jaw chuck? Shouldn’t be too difficult to mount in the 4-jaw to indicate it in true to center off the remaining good surface, then center drill for a true center. Weld build-up and machine to size referencing center drill bore.
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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.
 
mac1911 said:
Rotate.

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Magnetic chuck project

Picked up this chuck a while back for scrape price. It worked but just not 100% I did get it apart and found its just not traveling that last bit to get the plates lined up correctly. I am not a machinist and often these small jobs can be frustrating as how to approach a repair on this...
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Then the body could possibly be used as a reference, since the unworn portion of the shaft rotates in it.

If the shaft can rotate 360 degrees AND you can mount the body so the shaft is exactly vertical you can might be able to use that to machine the worn part. It will act much like a rotary table. But make sure that you aren't climb milling, you could break off the shaft. It isn't very large. Lots of light cuts, for sure. If the shaft is hardened, carbide or a grinding stone may be required.

This scheme is predicated on you being able to drive the shaft in a controllable manner while it's being subjected to milling forces. From here I can't tell if that's possible or not :).

The fact that you've got some strong magnets in there complicates things though, since the (presumably magnetic) swarf could get in and jam things up. Some duct tape might come in handy there.
 
homebrewed said:
Then the body could possibly be used as a reference, since the unworn portion of the shaft rotates in it.

If the shaft can rotate 360 degrees AND you can mount the body so the shaft is exactly vertical you can might be able to use that to machine the worn part. It will act much like a rotary table. But make sure that you aren't climb milling, you could break off the shaft. It isn't very large. Lots of light cuts, for sure. If the shaft is hardened, carbide or a grinding stone may be required.

This scheme is predicated on you being able to drive the shaft in a controllable manner while it's being subjected to milling forces. From here I can't tell if that's possible or not :).

The fact that you've got some strong magnets in there complicates things though, since the (presumably magnetic) swarf could get in and jam things up. Some duct tape might come in handy there.
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Chuck all cleaned up, inside and out
 
So I am no drafts man and I just a digital caliper. I can break out mics and depth gauges later when im closer to making it.

What I dont know is how much of a fit should be on the worn shaft to the cam hole. Im thinking its a bit under sized.
Im guessing there needs to be a little slop so the linkage does not lock up.5007F092-1515-4589-BF59-8437EE1F17E6.jpeg

The corner of the paper points to what I believe to be original diaimage.jpgB2E6E369-21DF-4670-BEEE-0E95922FA387.jpeg
 
The corner between the pin and arm looks like the pin was pressed in, if so, drill most of it out leaving a thin remainder, this insures you do not damage original hole.

With the center removed it should be easy to get out, then just make new pin, use a grade 8 bolt or something hard for this.


What is this from?

Sent from my SM-G781V using Tapatalk
 
tq60 said:
The corner between the pin and arm looks like the pin was pressed in, if so, drill most of it out leaving a thin remainder, this insures you do not damage original hole.

With the center removed it should be easy to get out, then just make new pin, use a grade 8 bolt or something hard for this.


What is this from?

Sent from my SM-G781V using Tapatalk
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Older Walker Magnetic chuck
 
tq60 said:
The corner between the pin and arm looks like the pin was pressed in, if so, drill most of it out leaving a thin remainder, this insures you do not damage original hole.

With the center removed it should be easy to get out, then just make new pin, use a grade 8 bolt or something hard for this.


What is this from?

Sent from my SM-G781V using Tapatalk
Click to expand...
It’s not a pin it solid one piece
 
Cadillac said:
It’s not a pin it solid one piece
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I dont see any signs of any pressed parts. Although it might end up getting a drilled and threaded post and then brazed ? Will see . I have a few pieces big enough to try something.
 
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