4 jaw chuck selection--Self centering or individual jaw adjustment type

[spacy]

I also use a 4 jaw scroll as my basic workhorse, better grip, holds round, square and also hex so no need to change chuck

 

[XD351]

Joe talks about this subject with a fair amount of detail in this video .
Fwiw i use a four jaw mostly as i found the minor inconvenience of having to centre the work outweighs the hassle of changing chucks .

 

[MachineTom]

how do you hold hex stock, in a scroll 4 jaw, and be concentric?

 

[larryg]

Let me say that I have never used a 4 jaw scroll chuck so I have a question. If you grip a piece of nominally square stock that is not exactly square, say 1" x 1.062, will two jaws not grip as tightly or not at all? It seems to me that one would have to have near a perfect square to have equal gripping pressure on the opposing pairs of jaws if the scroll was good.

lg
no neat sig line

 

[ki4byz]

For 1" x 1.062 you use a couple pieces of .030 shim stock on the 1" sides

 

[bazmak]

all rolled sq stock would be within a couple of thou.1" x 1.o6 is not sq stock

 

[johwen]

^^^ Yes, when you think about it there is no reason that a three jaw should be the default self centring chuck. Probably just tradition based on economy of manufacture.

As you say, better grip with a four jaw and really, how often do you need to grip hex bar? And if you do you can grip it in the SC four jaw with a round split bush around it. I think next time I need to replace a worn out three-jaw I'll get a SC four-jaw.

Johwen again. A four jaw self centering chuck will accurately hold a hex bar just jiggle it a little and it will chuck up dead accurate give it a try. I make nuts accurately using this set up. Can guarantee it saves so much time and will chuck all hex sizes within the capacity of the chuck! John

 

[spacy]

how do you hold hex stock, in a scroll 4 jaw, and be concentric?

if you look at my (fuzzy) photo you can see that one of the corners aligns between two jaws, it will centre perfectly like that

seems counter intuative I know

 

[comstock-friend]

The more you use an independent 4 jaw, the quicker the centering gets. It should be the go to chuck. My three jaw has hard and soft, the soft jaws are great when setting up for a pile of wheels and such. Small bar work, round, hex and square goes into my 1A collets on the 9" South Bend, 5C collets on the 13" SB.

This is my soft jaw set up on a 6" three jaw.

 

[MADJACK]

For years all I had was an independent 4 jaw chuck, with practice centering stock gets pretty quick. If I had to start with only 1 chuck I'd start with the independent 4 jaw.

Just my .02

 

[nel2lar]

Since buying a 4 jaw self centering chuck for a job requiring the turning of a large quantity of square bar the chuck has hardly been changed , I find that it does everything that I would use a 3 jaw for and more.

Abby, I can not agree with that. try to hold a piece of hex stock in a 4 jaw scrolling. The best chuck is the 3 jaw scrolling because it holds in only 3 points and it will hold better than any other. If you try to chuck up a piece of stock that has a unseen flats on it even if you have a 4, or a 6 jaw the part will start to move under turning. Every shop needs a 4 jaw independent adjusting chuck or at least a good face plate. Almost anything can be held on a face plate.
Nelson

 

[Wizard69]

I look at it this way if you don't have an independent 4 jaw chuck now, you eventually will have a need. There are other approaches to mounting parts for eccentric turning but over all a 4 jaw is a very flexible solution.

As for scroll chucks that is really a personal preference thing in my mind. You can get 3, 4 & 6 jaws models depending upon your needs and may even find 2 jaws chucks. As you can see in the comments people have their preferences

Honestly I'd suggest getting a heavier variant of a 4 jaw independent. One with T-Slots wouldn't hurt. If not T-Slots have enough meat in the chuck for drilling and tapping of holes. That is the face of the chuck meat for indexing holes around the rim can make for a very handy chuck.