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Old 12-13-2018, 09:10 PM
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LKeithR LKeithR is offline there a prize?
Join Date: Aug 2011
Location: Langley, B.C.
Posts: 5,159

Originally Posted by rmack898 View Post
...A 3-jaw chuck is a 3-jaw chuck, it will have "X" amount of runout, a set tru is a waste. If you keep the work in the 3-jaw chuck for all operations, then the part will be dead nuts true and concentric...
I tend to agree about set-tru chucks. They're only good at the one point where you set them, otherwise you still have a 3-jaw chuck with it's inherent runout.

Having said that, as far as I'm concerned--for the work that we do--a 3-jaw is more than adequate for most things. I am constantly making parts in a 3-jaw and swapping them end for end to finish off--the few thou of runout that you pick up often doesn't matter.

If your lathe is capable of parting off efficiently an awful lots of parts can be made in a 3-jaw with most of the features concentric to each other. Often all you need to do after parting off is to face the "back" side which, in many different situations, doesn't need to be perfect in relationship the the rest of the part.

...A 4-jaw scroll jaw chuck is useless as far as I'm concerned...
There aren't a lot of uses for 4-jaw scroll chucks but, like every other tool in the box, they do have their place. If you're machining round features on square stock they can be really handy--dialing square stock in on a 4-jaw is a pain in the ass.

As far as the size of your 4-jaw I think a 10" is just about the right size for a 14" lathe...

Measure twice and cut once...or...wait, was that the other way around?
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