Four jaw chuck super fast setup using this tool.

[Toolmaker51]

Here is a prime example of a thread hack, yet connects the range of suggestions accumulated by OP's post. Apology in semi-logical order of details, more overlaps than a line of senators beachside in Miami. (shudder shudder)

The only reasonable justification of a self-centering 4-jaw is production work; the variety with master jaws switched out for tooling that holds a casting etc.
Only use encountered was turret lathes and stock serrated jaws running material, basically cube shape iron castings. The uncut base was faced whilst chucked on turned end in a 3 jaw; became a sealing flange with 4 bolt holes in corners. Terminology-wise that was more chucker than turret, individual parts vs bar feed.

FWIW, there are self centering 2 jaws, 3 jaws, 4 jaws, 6 jaws.
There are independent 3 jaws, and 4 jaws.

All available (with sufficient $$$.$$) in solid outside jaws, solid inside jaws, reversible jaws, and 2 piece jaws.
Here, they separate into plain jaws and stepped jaws. Plain jaws can be radiused for OD, or carry a narrow point, mainly accommodating wider range of diameters.

At this level, 2 piece jaws have about 3 patterns attaching top to master; slotted, keyed, 60° serrations.
Some models offer soft jaws and hardened jaws.

Those diverge once more into smooth jaws and serrated tooth jaws. Typically, serrated jaws are hardened, in generating incredible grip, they're marring the surface, an 1/8" of aluminum averts that.

On rare occasions, an independent 4 jaw will be run just opposing pair, fitted with tooling for really off centered needs.

By the time you get 16" swing, consider a crane. There are various lifting types, gantry's seem most practical.

At about 24" swing, starts another option. There are face plates with four bolt-on jaws for horizontal lathes, otherwise like vertical boring machines. Always hard, serrated, some reversible by removing and turning around. Used sets? Start around $2500.

For my $.¢, best choice is 2 piece jaws, supplied with reversible serrated hard jaws offers greatest flexibility. Whether 2-3-4 or 6 depends what machine I'll hang it on. If you acquire lathes, an operative search begins considering which variety of spindle design.

I buy used. A South Bend and Logan share threaded spindles, the real lathes D1-3 and D1-6. Easiest to mount, reversible rotation, most plentiful therefore most economical. Holding out on a rather exceptional 14", just because bolt on chuck; on faceplate, different than what's known as A-1 type.

The real 'trick' dialing in is visualizing what needs to happen movement wise of part, not indicator. Often, I start by NOT having the indicator touch all the way around. Makes the high side very apparent, especially on larger diameters. Mounted on cross slide, it's plenty fast to adjust contact to final it in.
Here are two well-knowns with impressive credentials. Watch all, it's entertaining, or skip to 4:50, then 8:50.

[thehomeengineer]

Hi DIYswede
53 years old and still learning. This is a great method for square stock. Thank you for posting
The Home Engineer

[wizard69]

You still have to go thru the indicating process. I use the 4 jaw only if I have to use it. I always thought someone would come up with a self centering 4 jaw chuck but I have not seen one yet. There must be a better solution than all the measuring and indicating.

4 jaw scroll chucks do exist but I'm not sure why you would want one. The whole point behind general use of a 4 jaw is to get run out down to nothing or nearly so. Scroll chucks just are not that accurate even when new, with a little wear they can be terrible.

[wizard69]

Lots of good points here but I need to pull out one little point below.

Here is a prime example of a thread hack, yet connects the range of suggestions accumulated by OP's post. Apology in semi-logical order of details, more overlaps than a line of senators beachside in Miami. (shudder shudder)



By the time you get 16" swing, consider a crane. There are various lifting types, gantry's seem most practical.

I would like to say always consider a crane if you have to strain even a little bit. We currently have a guy out at work and frankly being a bit of a gym rat, he is the last person you would expect to be injured or out of commission. It is just way too easy to have something go wrong while carrying significant weight.

[mr_modify1]

Some interesting information. Thank you.

[WmRMeyers]

Believe me, you don't want a self-centering 4jaw. The independent 4jaw is both more flexible and more accurate.

Centering work in the 4jaw can be made much less tedious with a few homemade tools and a straightforward procedure. You may want to read my procedure here...

Centering work in the four jaw chuck

With this procedure, another dead simple addition can make centering polygonal stock much easier...

Centering aid for polygonal stock

I think a self-centering 4 jaw would be good for production in a shop that does a lot of turning of square stock. As long as you can tolerate the several thousandths of runout, just like with a 3 jaw chuck and round stock. Depends on how critical low runout is to your part, and how many of those parts you need to make. If you're making rocket parts, it's probably not going to be what you need. I'm probably never going to buy one. But I'm not doing production work, and I can take all the time I want to take to dial stuff in to ridiculously tight tolerances if I want to do it that way. YMMV! It almost has to.

Bill