Do You Use a 3 Jaw or a 4 Jaw Chuck?

British Steel said:
I rarely use the 3-jaws i have, they only come out when I can make something in one chucking or don't need to worry about concentricity of different features - anything that needs to come out to turn around, for instance, goes in whatever's most suited: 4-jaw, collets or between centres (between centres is the easiest for e.g. shafts that need to be tried for a fit but needs centre drillings in both ends... 4-jaw's essential for eccentric features (cranks, cams etc.), collets for repetitive work small enough to go through the spindle and collet.
A big help when setting up and indicating in the part in a 4-jaw is a second chuck key so you can work on opposing jaws together, makes it a lot quicker! That also implies that you'll need a decent indicator and mount to measure eccentricity, useful (and a nice easy lathe project) is a telescopic "pump centre" when you want to pick up a punch dot on an interesting part to drill / bore / ream - it goes between the tailstock centre and the punch mark and the indicator rides on it, adjust the jaws to centre it, easy peasy!

Dave H. (the other one)
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I saw a video where Kieth Rucker made a cross feed nut. The rectangular piece of brass had to be drilled. He followed your lead Dave. He used a center with a tang between the tail shaft and the center drilled brass nut. Found eccentricity for drilling and tapping using a micrometer on the center.
Watching someone center a rectangle in a 4 jaw chuck in a few seconds seems like magic to me.
I will work on it, I have a project ready to be drilled and tapped. It’s a rectangle.
 
i use 3 jaw, 4 jaw, ER32, 5C, and turn between centers at will.
it really depends on the work to be produced, as to how i hold it :grin:

the 3 jaw chucks get the most use.
if you are turning the od, the lathe will turn concentric parts even if your 3 jaw chuck is worn-
you just have to do all the operations in a single chucking to keep concentricity,
otherwise you'll introduce the error of the chuck to the new part
 
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Use my 5C about 50% of the time, I have an ER40 lathe chuck, but dealing with the wrenches is a PTA. Stiil the ER40 provides better holding power then the 5C and works well for odd size stock. I use a 1/32 ER40 collets set. Otherwise like Ray, I use my 8" Bison 4J combination chuck about 40% of the time as it is very quick to use the scroll to insert stock and you can dial down the TIR to zip in under a minute. It repeats within 0.001" with the same stock piece in/out. Works great and often I am working with dimensional stock that I need to use the full diameter, so I need to have minimal TIR error when holding the stock. I do have a 3J Set-True scroll that I use if I need to repeat multiple steps (in/out) on stock bigger than 1", i.e. that won't fit the 5C. If I was starting from scratch I would just get the combination 8" chuck and the 5C chuck.

Bison combination chuck holding 1.5" stock then flipping the piece to cut a 1.5-18 thread on the opposite end.
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5C is great for small stock.
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I use 5c collet chuck the most, doesn't damage work . For work 1.25 to 3 " diameter I use a 4 jaw 5c collet chuck, not the best holding power but is fast and easy.
 
Janderso said:
I got this piece centered in only 15 minutes. My first time using a 4 jaw.
Next time it won’t take long.
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Practice, practice and more practice, you'll get it below a minute ;)

Dave H. (the other one)
 
Congrats.....you can always use the 3 jaw as a door stop.
 
I did notice when I spun this rectangle in the 4 jaw there was significant runout. I have not measured it but the first time I mount a round piece of stock I will look into this further.
I must say, using the chuck and tail stock made quick work of this 3/4 LH tap.

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4 Jaw is great when you need to:
Turn square ou any weird form object
Face any part if you don't have a milling machine
Grip a round object acuratelly
Precisally drill a hole you punched

Practice and this two little tools help a lot when we set a part to 4 jaw.

 
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