Lathe Chuck

[Zebra13]

Gents,

I am looking at buying a new 6 jaw adjust thru chuck for my lathe. One thing that keeps popping up that I know nothing about is steel vs. semi-steel. The steel chucks are more expensive and advertise .0004 TIR repeatability. The semi-steel chucks are cheaper and offer .0005 TIR repeatability. The issue, as I understand it, is the semi-steel are more apt to wear quicker.

I am a hobbyist gun tinkerer, and my machines will never see production. I probably won't wear out a semi-steel chuck. But as I said, I don't know a whole lot about this, so I am deferring to those who do.

Any thoughts, experiences, advice, etc., would be appreciated.

Justin

 

[mike in co]

the set tru function is great for production..that is the repeatable portion. for us hobby gunsmiths. the adjustable portion is what we look for( in my opinion). i went with an inexpensive knockoff in three jaw. so far so good.

just my 2 cents worth

mike in co

 

[jackie schmidt]

For the Hobbyist, go with the lower knockoff. Since the thing is adjustable, the repeatability is really a non issue.

I would be willing to bet that if a company makes both Steel and Cast body chucks, the internals are the same.........jackie

 

[frwillia]

At home in your shop you probably can't measure the difference between .0004" and .0005" repeatability if you spend a month trying. Go with the less expensive one. You won't wear it out.

Fitch

 

[Mike Bryant]

Be aware that most 6 jaw chucks will tighten down just so far before the jaws will go no farther. For instance, my 6" 6 jaw Buck will not tighten down on a piece under .625" in diameter. I have a three jaw adjust tru Pratt Bernhardt chuck and the 6 jaw Buck. The Prat tends to be on my lathe a lot more often than the Buck. it's just plain more convenient to use for turning pillars besides doing barrel work. It gives up nothing for barrel work either compared to the 6 jaw. I use a .25" wide stainless ring between the chuck jaws and the barrel, so very little of the chuck jaws are bearing against the barrel at the chamber end.

 

[sbindy]

I'm sure I am in the minority, but I prefer a 4 jaw chuck to anything else when I have to make something as perfect as possible.

Mike, I also use a copper ring between the jaws and work. I read about that on this forum a short while ago and it is definitely the way to go.

 

[mike in co]

THE tru sets and clones are not hi torque applications, but for bbl work they are very quick...easy to set the bbl tight( within the limits of the chuck) and simple to zero...the holding power and the zero are independent of each other.
mike in co

I'm sure I am in the minority, but I prefer a 4 jaw chuck to anything else when I have to make something as perfect as possible.

Mike, I also use a copper ring between the jaws and work. I read about that on this forum a short while ago and it is definitely the way to go.

 

[kiwi smith]

May be a little off the subject, but I just got my new lathe delivered last week, and got a nice quality Taiwanese 3-jaw with it ('Strong' brand, KD6-8) 8", D1-6 direct mount. The repeatability of that with a ground steel bar is 0.0005" TIR measured. Pretty good for a 3-jaw in my opinion. I know a guy down south has one of the same chucks and he was happy with his doing under 0.001" TIR.

At least with a 3-jaw you can hold smaller work-pieces than a 6-jaw. Great for quick little jobs, but i still prefer the 4 jaw for anything that requires a real accurate set-up though.

Cheers,

Dean.

 

[mike in co]

why ???

At least with a 3-jaw you can hold smaller work-pieces than a 6-jaw. Great for quick little jobs, but i still prefer the 4 jaw for anything that requires a real accurate set-up though.

Cheers,

Dean.

 

[nhkuehl]

At least with a 3-jaw you can hold smaller work-pieces than a 6-jaw. Great for quick little jobs, but i still prefer the 4 jaw for anything that requires a real accurate set-up though.

I agree, my 4-jaw is easier to indicate in and more accurate. - nhk

 

[mike in co]

ok, me thinks you guys are confusing chucks.
a tru set or clone is a scroll chuck BUT IT IS ADJUSTABLE. the entire chuck moves on its backing plate.
they are easier to set up than a four jaw, because holding force on the work pc is independent of the zero.
so one of the two of you that say your 4 jaw is easier to indicate , that has worked with a tru set, please explain how and why the std 4 jaw is easier ?? please

mike in co

I agree, my 4-jaw is easier to indicate in and more accurate. - nhk

 

[nhkuehl]

Chuck preference

ok, me thinks you guys are confusing chucks.
a tru set or clone is a scroll chuck BUT IT IS ADJUSTABLE. the entire chuck moves on its backing plate.
they are easier to set up than a four jaw, because holding force on the work pc is independent of the zero.
so one of the two of you that say your 4 jaw is easier to indicate , that has worked with a tru set, please explain how and why the std 4 jaw is easier ?? please

mike in co

Why do some gunsmiths use spiders and backing plates with 4 set screws instead of a chuck to hold a barrel? I feel that by having my adjustment in two planes directly in line with my clamping force I have better control of accuracy so I use my std 4-jaw chuck and an outboard spider. If I turn between centers I use the 3-jaw scroll chuck and re-cut my dead center. I've fiddled with adjusting the 3-jaw scroll chuck and it's +/- .003", but I can adjust the 4-jaw to +/- .001". I know everyone will be aghast at those tolerances, but after you've indicated in your barrel check your runout with the lathe running and see what you get. - nhk

 

[Zebra13]

Why do some gunsmiths use spiders and backing plates with 4 set screws instead of a chuck to hold a barrel? I feel that by having my adjustment in two planes directly in line with my clamping force I have better control of accuracy so I use my std 4-jaw chuck and an outboard spider. If I turn between centers I use the 3-jaw scroll chuck and re-cut my dead center. I've fiddled with adjusting the 3-jaw scroll chuck and it's +/- .003", but I can adjust the 4-jaw to +/- .001". I know everyone will be aghast at those tolerances, but after you've indicated in your barrel check your runout with the lathe running and see what you get. - nhk

nhk

If I'm not mistaken, the purpose of the face plate and 4 set screw type of arrangement is to make one's headstock "shorter", i.e., it allows you to chamber a short barrel using the through the headstock method.

Justin

 

[mike in co]

but your zero is influenced by your clamping force.
i have the same thing with a tru set, i have two plane adjustment,but my zero IS NOT INFLUENCED BY MY CLAMPING FORCE.
i use a 4 screw spider on the outboard of the headstock, i clamp with a truset clone, and then zero. i re check both .....i recheck/reset after predrill/before boring and chambering.
clamping force affects zero in a 4 jaw independent chuck. not so in a truset.....
you like the idea,great, but how is it easier ???
mike in co

Why do some gunsmiths use spiders and backing plates with 4 set screws instead of a chuck to hold a barrel? I feel that by having my adjustment in two planes directly in line with my clamping force I have better control of accuracy so I use my std 4-jaw chuck and an outboard spider. If I turn between centers I use the 3-jaw scroll chuck and re-cut my dead center. I've fiddled with adjusting the 3-jaw scroll chuck and it's +/- .003", but I can adjust the 4-jaw to +/- .001". I know everyone will be aghast at those tolerances, but after you've indicated in your barrel check your runout with the lathe running and see what you get. - nhk

 

[nhkuehl]

Face plate

nhk

If I'm not mistaken, the purpose of the face plate and 4 set screw type of arrangement is to make one's headstock "shorter", i.e., it allows you to chamber a short barrel using the through the headstock method.

Justin

You're right. But the four screws in 2 planes is the easiest way to indicate in the barrel. Look at (Gre-Tan) action truing jigs, screws in 2 planes. - nhk

 

[Zebra13]

You're right. But the four screws in 2 planes is the easiest way to indicate in the barrel. Look at (Gre-Tan) action truing jigs, screws in 2 planes. - nhk

nhk,

Agreed. And an adjust-thru chuck works off of 4 screws on 2 planes. Either chuck, an adjust-thru or a 4 jaw (or the face plate with 4 screw set-up), will work, but I find the adjust-thru's easier to dial in than a 4 jaw.

Justin

 

[Ron of Va]

For what it is worth, the Bison 6 jaw adjust tru chuck’s adjustment screws are not at 90º to each other. It is a pita to get dialed in.

The orange tape indicates the location/relationship of the adjustment screws.

 

[mike in co]

one more reason to get the 3 jaw

For what it is worth, the Bison 6 jaw adjust tru chuck’s adjustment screws are not at 90º to each other. It is a pita to get dialed in.

The orange tape indicates the location/relationship of the adjustment screws.

 

[Zebra13]

Ron,

The Bison adjust-thru adjustment screws on my old chuck were not at 90's either, but I don't remember them being as close as the ones on yours. Mine was pretty easy to dial in. I'll see it tomorrow...I'll take a gander at it.

I could never figger out why they wouldn't have them at dead nuts 90's.

Justin

 

[WSnyder]

one more reason to get the 3 jaw

I have an 8" Buck and a 6 1/4" Bison 3 jaw set-tru's and the adjustments aren't at 90°. They are exactly the same as my 6 1/4" Bison 6 jaw set-tru. I've seen early Buck's at 90°. Neither of those chucks are a problem to adjust once used to them. I also have an 8" Yuasa Accu-Chuck with 3 adjustment points. Some people assume that it would be a pain but it's no big deal either. I took my Buck apart a while back to clean and lube it and could see in the design that there wasn't any room to put the adjustments at 90°. On one lathe we don't have a set-tru type chuck for it and we use a 4 jaw if we need to indicate something in. Something about a 4 jaw just makes it feel simple and easy to use. Set-tru, 4 jaw, whatever, they all work fine and do the job.

Another note on the semi-steel to steel question the steel bodied chucks usually carry a higher max speed rating. Probably not an issue with most lathes.