My NOS Rohm Lathe Chuck

I'm with Dave Paine - use oil on the front side of the scroll. I recommend Super-Lube grease and oil; it will not harden or cake with age.
 
It's so bad I don't know if I can salvage it. Or should I say keep it. Whatever that stuff was it's all over. I cleaned it I thought well but no. I just put in the scroll and it is binding like crazy.
The guy offered a refund but not sure if he's paying the shipping.
 
I purchased a used 10" Rohm 3-jaw chuck a while back. The the scroll was tight and would hardly move. Once I got it mounted and got the scroll moving, it freed up. What a nice used chuck, measured 0.002" tir on the first try. Played around with the stock and got it within .001". That's pretty good in my book for a used 3-jaw chuck. Rohm made and may still build nice precision chucks, if you can afford them. I have several new and used Rohm live centers, they are nice, too!
 
Get some MEK and see if that will melt/dissolve it off. Find some moly disulfide base grease and apply to chuck body area where the scroll move in. And put a dab or two on the scroll. That should let it turn freely. I hope that hard stuff is not some kind of Teflon/Rulon coating applied at the factory for lubrication.
 
What is binding? Do the jaws slide into their slots easily? Many new high quality chucks will have very tight fitting jaws that will loosen up with use. You need to determine where the binding is occurring if it isn't the jaws.
 
IDK Ken. I scraped as much off as I could and soaked the jaws and scroll mineral spirits. Seemed to soften it up some. Then brushed it off with a brass bristled brush. Started to put it back together and found more where the jaws slide on the body. At that point I just wanted to get it together.
Mike. Where the scroll slides down onto the body this stuff is all around where the scroll rests so it is binding where it is built up. Like I said I tried cleaning it off. I just hope it wears off. I will take the chuck apart soon again for cleaning. I oiled the scroll and greased the bottom where the pinions are with some general red grease. I don't have anything else so that will do for now.
You're correct Mike the jaws are very tight but there is for sure left over hard stuff as it scrapes off when the jaws close, I can see it on the edge.
So anyway I have ~a little less than .0008" runout and .0012" @ six inches. Very satisfied with that. Just not spending half of my day off cleaning the thing.
 
I would completely disassemble the chuck and clean it completely, then reassemble with the right lubricants.
 
This chuck is incredibly accurate and repeats beautifully.
It is loosening up some in the scroll but is probably time for another cleaning.
It has a grease port and am considering greasing it. Not sure yet.
A little disappointing the other night I was threading with a die, .500" steel and I could not hold the piece. It would slip in the jaws. This has happened a few times so far.
 
I am thinking that "light brown" stuff you described is affecting the clamping force.

All the sliding surfaces must be tight tolerance for a chuck to perform, from clamping to run out. Ken mentioned using an aggressive solvent soak and cleaning it up.

Your clamping issues are giving you a strong signal. If it was mine, I'd have it apart and soaking in something that would cut that stuff off all surfaces. I would try some MEK, acetone, or stout paint remover as a trial and then use the one that worked the best. Otherwise it will likely continue to interfere, cause unfortunate wear and damage a good chuck.
 
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