what size chuck advice for starter lathe guy

My 5" 3 jaw Bison averages .0012-.0015 runout after 8 years of heavy use for a hobby machine. The 10" Bison at work will still hold .002 TIR easily after 10 years of heavy, abusive use on our 15" Metosa.
Part of being a good machinist is knowing when you need the extra accuracy and when you don't. I have a nice 4 jaw, I use it here and there but I still use my 3 jaw the most. At work we work between centers or in a 3 jaw the most, I bet the 4 jaw hasn't been used a dozen times in the last 10 years.
 
maybe it's the small 3 jaws that hold their accuracy better my biggest chuck i own is 6"
you guys have a lot bigger chucks

as a rule of thumb I'll use my 3 jaw if i'm only using the part i'm machining off the end and not what is in the chuck
if i'm using the entire part and need it accurate it's time for the 4 jaw or even turn between centers for the best accuracy.
steve
 
WAY back in 1974 my NOS Union 6" chuck was .003" out. The new Chinese ones,or Taiwan ones that came new on 3 lathes I bought for work were .003" out. However,My Bisons are .001" or less. Just a better chuck.

I used the 6" unions for several years before getting a larger lathe. My standard chuck I keep on my 126" lathe is a Bison 4 jaw universal. I have a 12" 3 jaw,but seldom need to put it on. It just depends upon what size work you plan on doing.
 
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Ur all way more accurate than I... I have a 3 jaw self centering haven't tested it for accuracy but have made a few projects like a handle for the missing one and the like ...all pretty simple fun low risk projects watching spirals of metal and chips flying off of round stock... It's great testing the different speeds on different metals and.... Made a few threads....wow...look at me... I know pretty humble stuff


But what about grabbing square stock? Isn't that what a 4 jaw chuck can do well?
 
Giorgio said:
Ur all way more accurate than I... I have a 3 jaw self centering haven't tested it for accuracy but have made a few projects like a handle for the missing one and the like ...all pretty simple fun low risk projects watching spirals of metal and chips flying off of round stock... It's great testing the different speeds on different metals and.... Made a few threads....wow...look at me... I know pretty humble stuff


But what about grabbing square stock? Isn't that what a 4 jaw chuck can do well?
Click to expand...

yes you can hold odd shapes in a 4 jaw not just square and you can use a 4 jaw to turn a cam
steve
 
Giorgio said:
Ur all way more accurate than I... I have a 3 jaw self centering haven't tested it for accuracy but have made a few projects like a handle for the missing one and the like ...all pretty simple fun low risk projects watching spirals of metal and chips flying off of round stock... It's great testing the different speeds on different metals and.... Made a few threads....wow...look at me... I know pretty humble stuff


But what about grabbing square stock? Isn't that what a 4 jaw chuck can do well?
Click to expand...


Yes, the 4 jaw works for holding odd shapes for machining. Speaking of squares. I often use one of my 4-jaw chucks to take round stock, and machine it down to a square. I can do this in the lathe much faster than making passes on the mill. When you get to a rough size, then head over to the mill. Try it, you might like it. ;)
 
McRuff said:
My 5" 3 jaw Bison averages .0012-.0015 runout after 8 years of heavy use for a hobby machine. The 10" Bison at work will still hold .002 TIR easily after 10 years of heavy, abusive use on our 15" Metosa.
Part of being a good machinist is knowing when you need the extra accuracy and when you don't. I have a nice 4 jaw, I use it here and there but I still use my 3 jaw the most. At work we work between centers or in a 3 jaw the most, I bet the 4 jaw hasn't been used a dozen times in the last 10 years.
Click to expand...


Your stating some pretty low #s on these 8 and 10 yr old chucks . Bison is a good brand, yes I do happen to own a Bison too. But I dont concider them hi-end by any stretch.

Any chance you could back up these claims? Do a video of these chucks indicating ground stock of at least 3 diameters each, and showing the run out.

I for one, have never seen a well used chuck put out low #s like your stating, let alone a Bison that you say is used in a working envirment.

Not trying to throw bricks here, but I havnt seen a 3 jaw that holds that tight of tolerance, and not 8 or 10 yrs old.
 
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