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Truing 3J chuck jaws - another thread

Chipper5783

Super User
I’ve had this chuck a long time, the gripping section is getting a bit uneven. The jaws were bell mouthed ~0.003” radially. After watching Robin’s video, I felt I could do that.

As has been much discussed, the biggest challenge can be setting up the loading arrangement. There are a few options. Since I have two piece jaws, I made a ring that uses the inner jaws bolts. The project took a bit of thinking. I was concerned about making the ring too stiff and would not mimic typical jaw deflection (per Robin’s comments) - I ended up skimming the ring down thinner than the initial version.

The actual cutting was pretty straightforward. I simply a purchased a TBC insert ($8) for my 1/2” carbide BB. I ended up removing 0.006” radially, which cleaned the gripping surface to about 95% pristine. TIR just under 0.002”. I still have to clean everything up - pretty happy with the result.
 

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Xyphota

Ultra Member
Nice work! I haven't measured my little myford 3 jaw, but its pretty brutal. Maybe this project should be added to the docket.
 

PeterT

Ultra Member
Premium Member
DeeDee has a slightly different setup but I think equivalent. (Video is a bit longwinded). He has some nice iron in his cramped little shop.

 

a smile

Lifelong hobby - cold iron
Premium Member
I’ve had this chuck a long time, the gripping section is getting a bit uneven. The jaws were bell mouthed ~0.003” radially. After watching Robin’s video, I felt I could do that.

As has been much discussed, the biggest challenge can be setting up the loading arrangement. There are a few options. Since I have two piece jaws, I made a ring that uses the inner jaws bolts. The project took a bit of thinking. I was concerned about making the ring too stiff and would not mimic typical jaw deflection (per Robin’s comments) - I ended up skimming the ring down thinner than the initial version.

The actual cutting was pretty straightforward. I simply a purchased a TBC insert ($8) for my 1/2” carbide BB. I ended up removing 0.006” radially, which cleaned the gripping surface to about 95% pristine. TIR just under 0.002”. I still have to clean everything up - pretty happy with the result.

It's a perfect design, but it requires a lot of work and a lot of patience, but I like ---- thank you for the solution
 
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