Chucking up a barrel question?

B

bigngreen

Guest
I've been struggling getting my barrels set up through the headstock and concentric to the bore in less than a couple hours, I get close ( like under .001) then blow it and start jumping back and forth, I eventually get it but dang it is frustrating! I'm thinking that I tighten the 4-jaw and the rear spider to tight is causing the problem, but I don't want to have anything get loose either. Could someone give me a torque spec for the chuck and spider? I make my living with a torque wrench so my brain is kind of hard wired to find a torque range and work with in it, once I know what I'm feeling for I'm GTG!
 
Do you have something between the jaws and the barrel? If not you are bending the barrel. It would help to have aluminum or copper wire between the jaws and the barrel. I don't use a torque wrench or much torque for that matter. You are not hogging metal in chambering.
Butch
 
Thanks for the response! I use small strips of copper between the barrel and bolts in the spiders or jaws. It just seems by the time I get it dialed in and just about get the last few ten thousandths out I either have a jump or the jaws are so tight I have to back the opposite on of a little and then it's like starting all over again. I wish one of you all were close enough to me that I could just feel how much you tighten stuff, a torque is the only way I could think of getting the info I need.
 
Big....you need to start using about 40-50 inch pounds untill you learn..Remember when using a 4-jaw or spider don't try to remove your high point by tightening...swing the chuck 180 degrees and remove tension on the low point first then swing it 180degrees to tighten the high point (half value)...use minimum torque until you get down to the .0005 range then you can remove the high points by torquing...
You just need more practice on the 4 jaw/spider...you will get faster with practice...keep the torque low until you master the setup..

Eddie in Texas
 
Big....you need to start using about 40-50 inch pounds untill you learn..Remember when using a 4-jaw or spider don't try to remove your high point by tightening...swing the chuck 180 degrees and remove tension on the low point first then swing it 180degrees to tighten the high point (half value)...use minimum torque until you get down to the .0005 range then you can remove the high points by torquing...
You just need more practice on the 4 jaw/spider...you will get faster with practice...keep the torque low until you master the setup..

Eddie in Texas
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Click to expand...

This is the best way I have found and I struggled with the same problem you are having.
 
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eww1350 said:
Big....you need to start using about 40-50 inch pounds untill you learn..Remember when using a 4-jaw or spider don't try to remove your high point by tightening...swing the chuck 180 degrees and remove tension on the low point first then swing it 180degrees to tighten the high point (half value)...use minimum torque until you get down to the .0005 range then you can remove the high points by torquing...
You just need more practice on the 4 jaw/spider...you will get faster with practice...keep the torque low until you master the setup..

Eddie in Texas
Click to expand...

Perfect!! Thanks!! Being a mechanic I can relate to your numbers, ya I'm being way, way to aggresive and more in the ft-lbs range by the time I get it down under .001 and leaving myself no where to get the final few to be on the knats rear end.
 
Well, that video only tells a small part of the story. You have to, sooner or later, have the piece chucked tight enough to do any machining operations without it moving. And of course, while he has it radilly true, it might not be any where near square. That is an entirely different animal.

This seems to be another one of those things that in reality, is a simple common sense procedure, but can be overcomplicated by "overthinking" the situation.

By the way, if he is going to do any machine work on that brass piece, by the time he gets it tight enough so that it is secure enough as to not move, it will be distorted by the pressure of the chuck jaws. When he unchucks the piece, the part that he machined will in all likelyhood out of round.

Of course, I am aware that he is using this solely as a demonstration, but as I said, he is only telling a small part of the story...jackie
 
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