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6 jaw v. 3 jaw chucks?

I use a 6jaw only because I found a guy that had a stack of 10" adjust tru chucks new in the box on craigslist years ago, I wish I would have bought more than 1. It has been a great chuck but is still pretty stiff after about 8 years of steady use. Also it gets clogged with chips very easily and needs to be cleaned out often. If I need it to be a 3 jaw I can just remove 3 of the jaws.
 
I bought a 10" 6jaw for our 15"lathe 20 years ago. It was a cheap China adjustable no name. I use that lathe just about every day and it does just fine . It repeats ,001" on most all sizes and if any thing needs more I can dial it in. I made an adjustable stop out of a MT5 tool shank if I need it. They will push back on some heavy cuts but I don't put a cheater on the wrench , that's what the stop is for . I have never needed to swap to the 2 three jaw chucks that came with it thus have never used them. It came with a Sojuren collet chuck that was pretty beat up so I adapted an ER40 to it.

About 5 years in it started to lock up so I took it apart expecting the worse, after all it was "cheap Chinise". The only thing cheap was the lube. Very well made and after greasing every thing it has worked smoothly the last 15 years . Probably due for a relube it now. I seriously doubt any hobby guy will ever in their life time put as many hard hours on their 6 jaw as I have.
So it does everything a 3 jaw does and more, whats wrong with that . If I need heavy and rough I have an 18" I keep a 4 jaw on.

As for the knife edge jaws mentioned above I have only seen them as oe installed on T&C grinders and such. Leads me to believe they were made more for precision than brute force work as on general duty lathe work.
 
There's no advantage that a 3-jaw has over a 6-jaw.
3-jaws are more durable since the jaws are physically much larger. So there's at least one advantage. 3-jaws tend to be quite a bit less expensive, so for some that might be another advantage.

I'm not against 6-jaw chucks at all...brought home a Buck 6AT just yesterday in fact.
 
I'm surprised folks haven't mentioned 4-jaw independent chucks, that is what I mostly keep on my lathe, almost never use 3-jaw, and only use 6-jaw for thin material. 4-jaw independent generally should be more accurate.
 
I'm surprised folks haven't mentioned 4-jaw independent chucks, that is what I mostly keep on my lathe, almost never use 3-jaw, and only use 6-jaw for thin material. 4-jaw independent generally should be more accurate.

apples to oranges

The ONLY time a 4 jaw gets on any of my lathes is when chambering rifle barrels, other then that I have no use for them. Been years since I've put either a square or rectangular part in a 4-jaw chuck.

Unlike you I don't have the luxury of time to indicate in a round part in a 4-jaw everytime I change parts.

For my customers close enough is good enough. don't tell them that:)
 








 
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