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4jaw vs 3jaw

Suzuki4evr

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#1
Hi guys

I finally got some money saved up for a 4jaw selfcentering chuck. I do have an independent 4jaw and selfcentering 3jaw. Iwant to know is what you guys think. If you must choose between 4jaw and 3jaw,which one would you pick. Is really a clear winner or not? I know the 3jaw is the best when it comes to nut making out of hexbar,but for the rest is up in the air. Need to regrind my 3jaw chuck aswell.
 

f350ca

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#3
With a three jaw chuck all the jaws will tighten on round stock even if its out of round. Unless the four jaws can be adjusted independently they won't have equal clamping force.

Greg
 

Suzuki4evr

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#5
Thanks guys
I would give your opinions a thought. It's always good to listen what others have to say about a matter before making a decision.
 

Ulma Doctor

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#6
i agree with @chips&more
if you have a 4j independent and a 3 jaw scroll chuck, you really don't need a 4 jaw scroll chuck
you'd be better off buying a set true 3 jaw scroll chuck and be done with it.


there is another method of truing up work,
rather than explain it, i'll give the video of the method from Joe Pieczynski

 
Last edited:

Alan H

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#7
If you have the coins to get one, I am of the opinion that it is a big plus. I recently bought one and am mighty glad I did. They can be mighty expensive depending what you land on.

I am lucky to have the 4 Jaw combination and a 5C set-tru. To be honest, the 5C sees more duty but my combination 4 jaw is way better than my 3 jaw. Downside is that it is a bit heavy but worth the hassle.

You can take the work piece out and put it back without inheriting a bunch of run out - a Big plus. Here are a couple of threads/discussions on this in the past few months here on the forum.

http://www.hobby-machinist.com/threads/6-jaw-vs-4-jaw-chuck.58657/

http://www.hobby-machinist.com/threads/8-bison-4-jaw-combination-chuck.62323/
 

Alan H

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#9
Is it okay to hold hex stock in a 4J?
I'd use my 3 jaw for that but I don't turn much hex.

Guess it is just the nature of what I work on but it seems way more likely for me to be making hex in the mill.
 

Suzuki4evr

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#10
I have decided to take the 4jaw scroll chuck(10' bison) for my 1.5m btc mashstroy
lathe for 3 reasons. 1: The 4 independent chuck I have is good and all but very big and heavy,good for ofcenter jobs but takes time for setting up stock. 2: My 3jaw is a bit worn but still workable,but workpieces sometimes start to run out a bit. 3: I got it for a very good price at R3 000,that is just over $200. Brand new out of the box with 2 sets of jaws. I found out they are alot mor expensive. I just have to make a backplate for it,because I am not willing to pay almost half the price of the chuck. But that is not a problem making one. Thanks for your input.
 

Alan H

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#11
Congratulations - that is a screaming deal on the Bison!
 

Bob Korves

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#14
Guess there really is no reason to have a 3J that I can think of.
A three jaw has its uses. For quick and dirty work, get er done, it is fast. If the stock is bigger than the finished size, and it can be machined in one setup and then cut off, there is no down side to the 3 jaw. The finished work will be completely true to the spindle center. If the work is not round, hex, or some other multiple of three sides, then another choice might be better... It has its uses. Mine is rarely used, takes more time and effort to change it out than to dial in the 4 jaw. That equation might change a bit since I am now also mixing a collet closer into the mix.
 
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