2 Piece Reversible Chuck Jaw Repair

[dalmatiangirl61]

I'm refurbishing an older Union 3 jaw chuck with 2 piece reversible jaws, the #1 jaw has about .002" play between the upper and lower pieces in the tension/compression direction. On a 4 jaw chuck it would not be a problem, but its going to play hell with repeatability and runout on a 3 jaw. Simple solution would be a 1/8" wide by 3/4" long shim, if you could get it in without getting pinched between upper/lower halves, and easily lost if jaws are reversed. Other options that have come to mind are a schmear of JB weld, brazing, or silver solder, then file to fit. Still need to do some measuring to determine which surface needs to be built up. Searched previous threads, did not see this problem, ideas and suggestions would be welcomed.

 

[Gordon Heaton]

If the jaws are hardened, silver solder temps will ruin the temper. Is the wear in the top jaw or the master? You can get new top jaws for many chucks but they're expensive.

 

[dalmatiangirl61]

If the jaws are hardened, silver solder temps will ruin the temper. Is the wear in the top jaw or the master? You can get new top jaws for many chucks but they're expensive.

They are hard, but no way to measure hardness, I was able to knock down some burrs with a good file. I need to get it into lathe to figure out where wear is. #2 top jaw fits snugly on #1 bottom jaw. #3 top jaw has maybe .001 play on #1 bottom jaw. #2 & #3 top/bottom jaws fit snug as they should. Kind of thinking the top jaws may be replacements, no visible wear on the working faces, rest of the chuck shows wear.

 

[gbent]

Is hard chrome still an option? I've rebuilt several power chucks that way. Nickel may also be an option, no idea about its durability. For a cheap permanent repair on the top jaw if it really bothered me I'd tig it with some tool steel filler, then finish on the surface grinder.

 

[guythatbrews]

It may not be the prettiest but you can probably peen the offending edge and stone back to fit.That is if it's not too hard.

 

[Milland]

I would consider an electroless nickel buildup on the correct face, with a little investment it's a DIY with a relatively safe(ish) set of chemicals. And I think(?) no risk of hydrogen embrittlement.

Plating Kits - Nickel Plating Kits - Electroless Nickel Plating Kits - Page 1 - Caswell Inc

caswellplating.com

[Pretty disappointed they use the word silicone rather than silicon in their description. Unless it really is silicone used in the process...]

 

[john.k]

Do it yourself Nickasil coating is kinda interesting......last I heard the pro shops were $400 a bore ..........which is kinda crazy when every Chinese whipper snipper engine has a Nickasil bore and the whole thing costs $30...retail.

 

[4GSR]

Most any coating process, either it is nickel or chrome, you still have a problem with hydrogen embrittlement. Still have to cook the parts in a oven at 350°F for at least three hours. This temperature will not affect the hardness of the steel.