Lathe Chuck Jaw Positions

As said scroll chuck jaws are ground with them installed in the chuck body so it's best to keep them in the slot they were ground in. That's why they are numbered. Same goes for scroll chucks with multiple pinions, the one that is marked is the pinion used for tightening when grinding the jaws & should give the best repeatability. Of course I'm not talking about the more affordable asian import chucks that often don't have any of these markings.
 
To add, my Bison & Gator chucks, aside from the jaw numbering, the jaws are also marked with the serial number of the chuck body. I assume it's the same for other mfgs but if you buy replacement top jaws from Bison they come a bit oversized (not the slots) to allow for grinding to match the master jaws.
 
That's interesting Will. The jaws on the chuck that came with my PM1228 have what look like serial numbers stamped on one side of the groove.
 
IIRC 4 of the 5 past China chucks I had all had the jaws numbered on the side of the slots along with some sort of serial numbering. The chuck bodies had the slots numbered as well, visible in the slot when the jaw is removed. But none of those chucks had the same "serial" numbering on the chuck bodies that were on the jaws. The other one of those 5 had the jaws numbered but I guess they forgot to number the chuck body accordingly. :wink:
 
I didn't think to look inside the chuck jaw slots for a number. I just marked them with a grease pencil as I removed them and stamped them accordingly when I could see the number in the jaw groove.
 
On the chucks I had they were marked in the chuck body slot close to the outer edge (circumference). If you close the jaws far enough they can be seen. In fact that's how my Bison chucks were numbered also.
 
My bison chuck is numbered completely as will said, also as he said one pinion is numbered 0, the Made in England 6inch 3jaw that came with the lathe is also numbered completely with serials on each jaw as well as position, only one pinion on that chuck. I have an Enco 4inch I believe which is numbered, but the 4inch 5c 3jaw I have made in China only one jaw slot is numbered, but it's obvious which slot is number 2.
 
Rohm, a real quality manufacturer, numbers the jaws but also sells sets of jaws seperate from the body.
I guess they count on their quality in making each set a perfect fit to each body.
 
janvanruth said:
Rohm, a real quality manufacturer, numbers the jaws but also sells sets of jaws seperate from the body.
I guess they count on their quality in making each set a perfect fit to each body.
Click to expand...

I doubt that. Pretty much all chuck manufacturers sell replacement jaws & other parts. You still have to grind the chuck jaws once installed on your chuck. If you have an adjustable TIR chuck you can get away without grinding but it's still recommended by the manufactuerers.
 
When I got my Grizzly G-4000, the external jaws were too tight to fit in the chuck. I was a complete newbie and couldn't figure out how to grind them (I think I tried filing them some). I call Grizzly and they sent me a replacement set of outside jaws that were a perfect fit. I can't remember if they wanted the original jaws returned, but I don't have them anymore and it's not the sort of thing I would throw away, so I must have.
 
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