Three or Four jaw self centering

[garagemark]

I do not have a three jaw chuck for my old SB 9", but... I have a four jaw independant and a four jaw self centering. Niether are world class, but they both work well. Any real reason to purchase a three jaw chuck? Any advantage (or disadvantage) of having three verses four with self centering feature?

THX

[CountZero]

Easier to hold hex stock and other shapes dividable by 3?

[Ian B]

Only reasons I can think of ar ethat 3 jaws will always grip, whereas a 4 jaw might be tight on 2 jaws, loose on 2 others. If yours grips round bar ok, then don't worry.

Also, 3 jaws will hold hex bar, nuts etc - but for the number of times you probably need that, use the independant chuck.
Ian

[airsmith282]

i have only the 3 jaw and i do like it but 4 jaw as it advantages for both the indepentdent and self centering, the 3 jaw chucks are good for round triangle and hex but thats about all they are good for..

[garagemark]

Have never needed to chuck up a hex shape yet, but hadn't though about that aspect. So far though, it doesn't seem justify a three jaw for me.

The four jaw seems to hold a round just fine.

[Black_Moons]

garagemark: stick with the 4 jaw, if you have a mill you could make some 60 degree 'v' blocks to hold hex in it without maring the corners.

Maybe put a 3 jaw on the 'buy if I find a good one for cheap somewhere' list.

Never seen a 4 jaw self centering, must be kinda nice.

[knudsen]

My independent 4 jaw has not left the lathe since they got married. I suppose I might take it off if I had to do a bunch of hex, but for one or two, probably just use the 3 jaw on the RT and make a round nipple on the hex to grab with the 4 jaw. Indy 4 takes seconds to reach the accuracy of a three jaw, seconds more to get almost no runout.

[Terry L]

Many years ago, when I was learning the machine trade, the lathe I had to work with only had a 4 jaw independant. I believe that was a good thing, because I didn't know any better and I got very comfortable with chucking up most anything with it. Now that I am retired, I have a small 13X36 lathe here at home and I have both the 3 and 4 jaw. However, my favorite is and will always be the independant 4 jaw. I have heard of the self centering 4 jaw, but don't believe I'd ever have the need for one.