Took apart 4 jaw independent chuck, now it's hard to turn the screws

Pcmaker

Pcmaker

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I have a Precision Matthews 11x27 lathe. I put in the 4 jaw independent chuck yesterday to get used to it and I noticed that there's a tiny bit more resistance when turning the screws when compared to my 3 jaw chuck. So, I took it apart. Took off the jaws and the backplate, but I numbered the jaws first so they go in the same spot when putting it back together. When unscrewing the jaws out, it became extremely hard to turn towards the end, just before them putting out, but I managed to get them out. I couldn't get the large pins that hold the screws in place out. I gave up after tapping them with a punch and hammer. All I did was spray down the screws with WD40. They turn freely and easily without the chucks on.

When I put everything back together, jaws in the same area they came out of, it was very hard to turn the entire way. It's way worse than before and it's all the jaws, not just one. There's only one way to put the jaws in, so I couldn't have messed that up. I just pushed it in and turned the screws until the threads engaged, but it was tough getting them all in.

I took the jaws apart again and looked at the scrolls. Everything is free of debris, including the threads on the jaws themselves. What gives?
 
Could it be you need to add lubricant? Take apart and degrease, clean then put together without lube?
 
I took it apart again and lubed it up with WD40 even more and still the same issue. the heck is going on. I had sprayed off the grinding dust with WD40 and that's about all I did. I thought that would make it turn easier, not worse.
 
Remove the jaws and check to be sure there no burrs on the alignment slides, on the chuck as well on the jaws and screws. Since the jaws are each independent, I would try to install them in different positions to see if they work any easier.
 
You may have to do some stoning on the jaws and chuck body. Sometimes they are a bit tight. I had to do this with mine.
 
What do you call those stoning tools? And what sizes do I need to get? I've always wanted a set, but don't know what they're called so I can order a set from Amazon.
 
I had a similar problem with the 4-jaw that came with my PM1236. A good cleaning & stoning helped a little bit but one jaw was always tighter than the others & the others felt a bit on the sloppy side. The only thing that helped the most was swapping the jaws to different slots. Played around & found a good combination that was ok. Finally I got sick of it, sold it, & bought another chuck.
 
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