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



## CDarby67 (Apr 4, 2019)

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

Thanks,
Clint


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## RJSakowski (Apr 4, 2019)

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.


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## Latinrascalrg1 (Apr 4, 2019)

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.


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## Mitch Alsup (Apr 4, 2019)

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.}


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## markba633csi (Apr 4, 2019)

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


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## Bob Korves (Apr 4, 2019)

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...


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## Suzuki4evr (Apr 4, 2019)

CDarby67 said:


> 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?


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## projectnut (Apr 4, 2019)

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.


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## Buffalo21 (Apr 4, 2019)

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


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## Suzuki4evr (Apr 4, 2019)

Buffalo21 said:


> 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


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## wrmiller (Apr 4, 2019)

3-jaw for holding roundy stuff, 4-jaw for holding non-roundy stuff. 

(actually, I use my mill for putting holes in non-roundy stuff...)


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## Technical Ted (Apr 4, 2019)

It's been my experience that a four jaw chuck has better work holding potential because you have four gripping surfaces (vs 3) and these are opposed to each other (facing each other) for better gripping power. So, if you need to hold onto the very edge/end of a work piece, the 4 jaw has a better chance of holding it without it becoming airborne!

When I was a tool maker, we had four lathes and 3 jaw chucks were VERY seldom used. From daily use, everyone got pretty fast at dialing thing in.

Ted


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## mikey (Apr 4, 2019)

All the above. I just wanted to clarify that when you first turn a work piece in a 3 jaw chuck, the result will be concentric with the centerline of the lathe; this is called a first operation. Most stock is not round to begin with and dialing it in in a 4 jaw for a first op turning is not necessary. Once you turn that piece and remove it from the chuck then you need a way to accurately dial it back in to the lathe centerline if further work needs to be done to it; this is called second operation work. This is when a 4 jaw independent chuck is most useful. The 4 jaw is also used to mount a work piece off center. Collet chucks are also commonly used on second operation work, especially if the part is threaded or delicate/thin-walled. 

Most of my work is first operation stuff so I use a 3 jaw most often. If I do a second op on it then I am more likely to stick it in a collet chuck. I use a 4 jaw independent when I need to really minimize run out on the part and I'm not clamping on a threaded section. If I had to choose chucks, I would get a 3 jaw for most work and a 4 jaw independent. Leave the collet chucks for later.


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## CDarby67 (Apr 5, 2019)

Mikey,
              Is there a video you can recommend to help me learn about using 4 jaw chucks when doing second op work? Collet chucks are out of my skill set - I am a complete beginner, however, I have need of them as you mention. Most of what I will be making are (relative of course) thin wall parts.

Thanks,
Clint


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## projectnut (Apr 5, 2019)

Here's a link to a video by mrpete222 (Tubalcain) setting up a 4 jaw chuck.


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## Bamban (Apr 5, 2019)

The answer is a combination 4J


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## darkzero (Apr 5, 2019)

No no no, you guys are doing it all wrong. You need an 8 jaw chuck! 

(If you can even swing a 60" chuck, sorry I couldn't resist)


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## mikey (Apr 5, 2019)

CDarby67 said:


> Mikey,
> Is there a video you can recommend to help me learn about using 4 jaw chucks when doing second op work? Collet chucks are out of my skill set - I am a complete beginner, however, I have need of them as you mention. Most of what I will be making are (relative of course) thin wall parts.
> 
> Thanks,
> Clint



The video from Mr. Pete is a good one. If you own a 4 jaw chuck, learn to use it well. With patience and skill, it will be the most accurate chuck in your shop. However, if you are going to work on a lot of thin-walled stuff then a collet chuck is the appropriate work holding method for you. Depending on your lathe and the size of your work, this might be a 5C or ER collet system. If the work is large then a 6 jaw chuck might be the answer. More details would help us to help you.

Forget the 8 jaw chuck - we'll all go over to Will's house and use his!


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## projectnut (Apr 5, 2019)

I have a variety of chucks for both lathes.  Both originally came with a 3 jaw and a 4 jaw chuck.  Since then I have added 5C collet chucks for both and a number of different size 4 jaw chucks.  By far the most used are the 4 jaw chucks.  Second most used are the collet chucks, with the 3 jaw chucks pulling in a distant 3rd.


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## MarkM (Apr 6, 2019)

Sometimes using the jaws for indexing using a lathe dog.  A four jaw you can make a double start or four (four not used much) and with the three jaw you can make a triple start thread.  Turn a centre and place in the chuck using a lathe dog being indexed using the jaws. Done between centres.


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