4 jaw independent chuck

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4 jaw means that every jaw adjust independently of the other 3 jaws allowing you to hold odd shaped pieces and drill different areas of them or turn them, as in a square, rectangle, oval, triangle or any other odd shaped piece.

PS: you can also get a 6 jaw chuck:biggrin:
 
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We use a 4 jaw to hold square stock for turning. It takes a bit of practice to set up a piece but once you learn it goes pretty quick, Invest in a few Mighty Mag dial indicators Mighty mags are one of the handiest indicator holders you can get, and some are pretty cheap, even the genuine ones are under 20.00 and you can get an imitation one(which work nearly as well), just not quite as strong of a magnet as the real Mighty Mag's, with a 1 inch travel dial indicator for under 20.00, from Enco.
 
Timebandit said:
4 jaw means that every jaw adjust independently of the other 3 jaws allowing you to hold odd shaped pieces and drill different areas of them or turn them, as in a square, rectangle, oval, triangle or any other odd shaped piece.

PS: you can also get a 6 jaw chuck:biggrin:
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THAT MAKES SENSE!!!
 
A 4 jaw chuck will also hold parts a little better with less clamping pressure then required for a 3 jaw, I used to turn large brass bushings with 7-9" hanging out of the chuck and only chucking on about maybe 3/8" or less, try that with a 3 jaw chuck and you have to clamp so tight it will squeeze the thing out of the jaws.

I know why would you do that.. why not slide it in more to clamp on the whole jaw width. Reason being is we turn the ID and the OD of the bushing/bearing in one chucking then turn it around and cut off the 3/8" we were chucking on, this also keeps the bushing/bearing from being squeezed out of round with the clamping pressure, hence the wall thickness is consistant, and the part is round.
 
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For a metal lathe in particular, if you ever want to do something like turn a cam or oval or put a radius down one side of a square bar a 4 jaw is the way to do it.

Once you get the hang of using (adjusting) one you can also use them to hold round stock very, very accurately as well, so you usually don't have to switch back and forth with a three jaw very often.
 
They are good for holding big parts, too. New center bands for a large pen(haha) Notice the normal size pen laying on the pallet in the first pic!
 

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Paul in OKC said:
They are good for holding big parts, too. New center bands for a large pen(haha) Notice the normal size pen laying on the pallet in the first pic!
Click to expand...

Looks like some of the stuff I used to work on years ago, we had a 52" and 104" Vertical Turret lathes, also had a floor mill that I used to face the ends of the cooling pipes for the San Onofre Nuclear plant, Had to use a 36" fly cutter. We made 33 miles of the pipe (if I remember right it was 60" in diameter), and it's all sitting on the floor of the ocean going out to sea in front of the plant.
 
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jd99 said:
Paul in OKC said:
They are good for holding big parts, too. New center bands for a large pen(haha) Notice the normal size pen laying on the pallet in the first pic!
Click to expand...

Looks like some of the stuff I used to work on years ago, we had a 52" and 104" Vertical Turret lathes, also had a floor mill that I used to face the ends of the cooling pipes for the San Onofre Nuclear plant, Had to use a 36" fly cutter. We made 33 miles of the pipe (if I remember right it was 60" in diameter), and it's all sitting on the floor of the ocean going out to sea in front of the plant.
Click to expand...

That's big stuff. Never ran a VTL, but been around one or two. Biggest was a 34" chuck machine one time.
 
A truly detailed explanation of the uses of a 4 jaw is probably more than what you would want, but for precision work 3 jaw chucks are very rarely used.

The obvious advantage of an independent 4 jaw chuck is of course that you can change the center of rotation for drilling off-center holes, machining cam shafts, holding squares, etc...

The more subtle (and perhaps important) advantage is that they are significantly more accurate when repositioning work. If you ever try unclamping a piece of stock in a 3 jaw chuck and putting it back in at a different angle (or to machine the other end) you are likely to be off by a few thou. This would be unacceptable for a lot of precision work. With a 4 jaw chuck you can set up an indicator and make sure it is dead on.

The process can be rough the first few times but it can become very fast with practice so in some cases it is easier to just leave the independent chuck on the lathe.

Six jaw chucks are somewhat ambiguous but everyone will agree they are good for thin tubing (more points of contact so less likely to crush the tube). Some people recommend 6 jaw chucks instead of 3 jaw chucks because they tend to be more expensive and therefore are built far more accurately.

Note that when you clamp round stock that is slightly oval in shape in a 6 jaw chuck it is possible for only two of the jaws to be in contact with the material and in some cases this can be dangerous. You occasionally hear stories of material coming lose so some people do not recommend 6 jaw chucks unless you are turning hex stock or tube.
 
Curly said:
Each chuck has it's pros / cons and best uses or they wouldn't exist. I like my 4 jaw scroll chuck on my metal lathe because it grips square and round pen blanks nicely. It is one of these. :smile: SB1313 6" Hi Precision 4 Jaw Scroll Chuck
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but that is not the type of 4jaw chuck we were discussing. those are not independently operated. that is just a better gripping and probably little more accurate version of three jaw.

Sent from my Galaxi via forerunner
 
Point taken. As 3 and 6 jaw chucks were mentioned I offered the 4 jaw scroll as a discussion option for those playing with square and round stock that don't know they are also available. The 4 jaw independent is the more versatile chuck as it can grip almost anything, with faceplates holding what the 4 jaw independent doesn't.
 
Thanks folks. As I research I am liking the 4 jaw independent chuck a lot for its versatility, and repeatable accuracy. This will be essential for what I want to do.

I have also noticed that they can be a great deal cheaper than self centering ones. My wallet likes that.
 
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