When to use a 3 jaw chuck vs 4 jaw chuck. Choices.

[CDarby67]

Gang,
why would a maker choose a 3 jaw chuck vs a 4 jaw chuck, or vise a versa?

Thanks,
Clint

 

[RJSakowski]

3 jaw, convenience; 4 jaw, minimal runout. Also there are times when you would want to mount a part off axis or mount a non-cylindrical part so a 4 jaw is used.

 

[Latinrascalrg1]

3 jaw=Quick but also not super precise due to runout
4 jaw= longer setup times but can be dialed in to be very precise.

 

[Mitch Alsup]

In addition, there are times when you are working two parts and you need both sets of chucks to get the job done {i.e., leaving both parts in both jaws and swapping jaws on the lathe headstock.}

 

[markba633csi]

Not to say that a 3-jaw cannot produce accurate parts, it can; as long as all the machining operations are done without removing the part from the chuck.
But as soon as the part is removed it cannot be re-mounted with the original accuracy. Usually. A 4-jaw can be re-adjusted each time the part is mounted to give essentially zero runout, but it takes time. Some get very good at it (not me)
Mark

 

[Bob Korves]

Beyond the good posts above, 3 jaw chucks work much better at gripping material with 3, 6, or 9 sides. 4 jaw chucks are better for work with 4 or 8 sides. Either will hold work with 12 sides or round work. 3 jaw chucks are much faster to use, 4 jaw independent chucks will allow dialing in the work for accurate centering with minimal run out. You really need both for doing all kinds of work, though the 4 jaw is more versatile, get it first if money is tight...

 

[Suzuki4evr]

Gang,
why would a maker choose a 3 jaw chuck vs a 4 jaw chuck, or vise a versa?

Thanks,
Clint

Just checking, do you mean 4jaw independent or scroll chuck?

 

[projectnut]

Adding to AJSakowski's statement a 4 jaw chuck can be used to fabricate cams, and bore off center holes. I just finished 2 sets of cams for a sheet metal brake. One set was to make fine adjustments on the grip of the upper platen, the other set were the ones used to open and close the platen. Both sets required a 4 jaw independent chuck.

As for taking more time to dial in a 4 jaw, I would agree that in the beginning it will take considerably longer. However the more practice you get the less time it will take. After many years of practice I find a 4 jaw independent more often than not the go to chuck. It generally takes less than a minute to dial a 8" or 10" 4 jaw to within .001". That's close enough for most work. It can get tedious to dial into .0001", but then again I don't know of a 3 jaw scroll chuck that's capable of that close tolerance.

 

[Buffalo21]

That why you need at least 2 lathes, one set up with a 3 jaw and one set up with a 4 jaw.............

 

[Suzuki4evr]

That why you need at least 2 lathes, one set up with a 3 jaw and one set up with a 4 jaw.............

The words of a true machinist