Old chuck jaw refreshing

[jwmay]

So I've got an old chuck with .011" runout. It's fairly repeatable across diameters. I can see that the jaws are bell mouthed.
The only reason I can see for me to own a tool post grinder is for this one issue. I don't want to use a grinder anyways. So... what are the odds I could charge a brass rod with lapping compound, hold it in the tailstock drill chuck, turn on the spindle motor and lap out the discrepancy?
Things to keep in mind: 1: The chuck has other issues and has no resale value. 2: The chuck will continue on being ballast if I can't fix the run out. 3: I've really got nothing to lose, because I have other chucks in the drawer, and another in the way by mail. 4: Remember number 1.

 

[ErichKeane]

11 thou is a TON to lap out (more than 6 per jaw!)... You could try, but it would take a long time. It would also introduce issues if your tailstock isnt perfectly centered.

 

[mikey]

I would just replace the chuck.

 

[francist]

This may sound dumb and goofy thing to do but a quick set of copper liners may buy you some extra life from the chuck. My main three-jaw is and has been bell mouthed for some time but I discovered every time I used my copper jaw liners it gripped a lot better. So I kept doing it, and still keep doing it even though I have since acquired an NOS chuck of the same size.

I think what happens is the copper conforms a bit after a few uses and actually takes on some of the bell-mouth shape in the jaws except in reverse, so in a way nullifying the wear in the jaws to a certain degree. I’m not proposing this makes a new chuck of the old, but it’s a cheap work around that might coax a bit more life out of the old piece. Works for me.

-frank

 

[benmychree]

If the chuck is otherwise in good condition, I would regrind the jaws, otherwise consign it to EB.

 

[ErichKeane]

I wonder if you could grind the old jaws into a 2-part jaw (like many chuck designs), and make the new parts out of something like 4140HT, and just turn them to size?

I also wonder if you could find some carbide capable of cutting the jaws and just turn them in place? Jaws tend to be softer than HSS (ask me how I know!), and carbide can do a so-so job cutting them. @davidpbest might have some recommendations!

 

[benmychree]

Life is too short to do suchlike.

 

[jwmay]

If the chuck is otherwise in good condition

Oh this chuck is no wise in good condition. More a sacrificial lamb of my early days to be honest.

I wonder if you could grind the old jaws into a 2-part jaw (like many chuck designs), and make the new parts out of something like 4140HT, and just turn them to size?

They're pretty hard, judging by one of my less expended files. I don't have a surface grinder, so grinding seems out. And then drilling and tapping for screws to hold the soft jaws would also be off the table. Although I suppose in the interest of science, they could be annealed and machined thusly. I've had a homemade forge sitting under my bench for a year waiting on a purpose.

I also wonder if you could find some carbide capable of cutting the jaws and just turn them in place? Jaws tend to be softer than HSS (ask me how I know!), and carbide can do a so-so job cutting them

Alas my poor Atlas, while ever ready to try a daunting task, is probably not up to that beating. Perhaps I'd be willing on a more robust machine. But me and this old girl have history, and I'm probably a little over protective.

 

[ErichKeane]

At that point, I think I'd just invest in a better 3 jaw chuck. Chucks for those atlases are typically pretty cheap/easy to come across.

 

[jwmay]

At that point, I think I'd just invest in a better 3 jaw chuck. Chucks for those atlases are typically pretty cheap/easy to come across.

Yep. Got that covered. This is just kind of a curiosity. Something to try. Maybe an alternative for the TP grinderless. I've never done any machine lapping. It seemed like a kind of effortless idea. Just turn it on and let it run, check on it every twenty minutes or so...But if we're talking days, maybe not so great.