Inexpensive 6" 3-jaw Chuck Revisited

[MikeMc]

Not realizing that there are 2 surfaces involved in getting a good fit between chuck and spindle the bore of my backplate is about 0.005" too large. At this late date I can't say whether I did it to myself or it came that way.
Today I tried supergluing 0.002" AL foil into the bore. That didn't work as the soft AL distorted so I went to the hardware store and bought a 0.002" x 1/2" x 12" steel feeler guage. I'll try gluing part of that in tomorrow.
I also bought an 8" 4-jaw from Enco but had to go to CDCO for the backplate. I asked one too few questions and when the backplate came I found it's unthreaded bore is 1.515". I'm not even tempted to try shimming it but remember from my youth that 'Liquid Steel' or some such product claims to be machinable. Has anyone ever done this or has reason to believe that it's too brittle for a 0.007" layer of work in a chuck? If so is there a prefered brand?
I can bore and sleeve these backplates but that's a lot more work that I'd rather not have to do.

Thanks for your thoughts,
Mike Mc

 

[Kernbigo]

Don't waste your time make it into adjustable like a buck chuck. I did mine years ago and no regrets.

 

[T Bredehoft]

I found it's unthreaded bore is 1.515". Uh...What's the thread on the end of the spindle. If it's 1 1/2, .007 shim isn't going to do anything. Do not consider plastic steel, you might wind up wearing the chuck.

What I did on a too large ER40 collet holder, was to bore it out, oh maybe 3/8 bigger, put a sleeve in it, and thread the sleeve to fit the spindle. I pinned the sleeve to the collet holder with four setscrews, drilled and tapped into the joint from the end.

 

[wa5cab]

I'm inclined to agree that your only solution is to bore, sleeve, and bore. Install the sleeve with Loctite (don't know what they call the correct product today as they seem to have changed the names again). I wouldn't trust plastic steel or anything similar. You could have the bore built up by one of the flame spray processes, which would then have to be ground to finish. That would give you a bore that you could never wear out. Unfortunately, it would probably cost more for one piece than a new chuck.

 

[MikeMc]

Kernbigo,
While I don't understand how your solution applies to my problem, I thank you for offering it and for a chance to see what your chuck is going to look like next week on the fourth of July.

Mr. Bredehoft,
A 7mil shim wrapped around the bore would bring the ID down to 1.5001". Thank you for your opinion of 'plastic steel'.

Wa5cab,
I was considering sweating the sleeve in but LockTite sounds like a simpler solution.

Thank you gentlemen for sharing your experience,
MikeMc

 

[Kernbigo]

I miss read your problem, but i have bored out a baking plate and re sleeved it with a 1 1/2" 8 on a 3 jaw chuck, lock tite it and use set screws in the end both to be safe.

 

[MikeMc]

I want to say thanks again for the input I've gotten here. I bored, sleeved and bored the backplates for the 6" 3-jaw and 8" 4-jaw. The TIR on the 3-jaw is down to 0.003" and the 4-jaw is 0.0015". Not great but good enough for now. I bored 0.250" over to have 0.125" sleeve wall. I put the sleeves in with red LockTite and drilled, tapped then faced off 8-32 screws so they're there 'til I bore them out again.
It's been 30 years since I worked as a machinist and I don't remember having trouble measuring IDs but I had Mitutoyo telescoping guages then where I've HF ones now which are much looser. None the less I had to make a second sleeve for each backplate to get a good fit.
Of course it's the cheap tool. I'm much better than that. ;^)>

The second pic also shows a saddle made from 4x4 to make handling the chucks easier and I'm wondering if anyone has a different/better way.

Appreciate the help,
MikeMc

 

[roadie33]

The 4x4 saddle is a good idea. I need to do something like that for my big 8" chuck.
If I get any larger chucks I'll have to start using the hydraulic hoist to change it out.

 

[Terrywerm]

The 4x4 saddle is a great way to go. I've got two of them, one for my 8" four jaw and one for my 6" three jaw chuck. Setting the chucks off onto their saddles is much better than trying to 'catch' them and then end up dropping them on the ways of the lathe!

 

[wa5cab]

I've been using a saddle like that ever since I figured out that the increased bother with changing chucks wasn't a matter of the chuck getting heavier with age.