MetalworkingFun Forum

Good discussion. I knew I had read about a master jaw somewhere.

Ed

I also read about a master jaw and tried on my friends 3 jaw and found that one of the jaws did result is less run out than the others. I can't recall the amount but less is less, which can only be good

I marked the jaw and will have to see if it is #1

I have a Pratt-Burnerd Super Precision 3-jaw scroll chuck on my dad's lathe. I got it for $200 from a Harrison lathe distributor who had dropped it and damaged one of the top jaws.

It runs out less than .0005" no matter which of the 3 holes I use.

Well I have zero run out on my 3 jaw, as I currently have to hold it in my 4 jaw!

(01-24-2013, 06:39 PM)Mayhem Wrote: [ -> ]Well I have zero run out on my 3 jaw, as I currently have to hold it in my 4 jaw!

Good one!

One of my 3 jaws has a socket marked with a "O" and it is considered the primary socket. it does seem to yield a better ruout than the other two. Not all chucks are so marked, but it might be worth going through and seeing if there is a consistently better result using one over the others and marking it as primary.

Heavy cuts, I tighten all three.

(01-24-2013, 07:50 PM)Tony Wells Wrote: [ -> ]One of my 3 jaws has a socket marked with a "O" and it is considered the primary socket. it does seem to yield a better ruout than the other two. Not all chucks are so marked, but it might be worth going through and seeing if there is a consistently better result using one over the others and marking it as primary.

Well, I'll be......

I just went and looked at my chuck. So THAT'S what that means?
All these years and I never knew.

[attachment=4322]

Willie,

That poor chuck (and it's holder, the lathe) appear to have never done any serious machining. Get to it man!

Just kidding!

The guys that pick up my trash might argue that point Ken.



Besides, you can't see the "zero" mark on the chuck from down here.