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Concentricity Gauge

 
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  #15  
Old 12-11-2012, 01:41 AM
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Join Date: Apr 2012
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Re: Concentricity Gauge

Handloader1, thanks for the suggestion. Is there a sure fire method of squaring dies or should I go with the rubber O ring method. All input is appreciated.
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  #16  
Old 12-11-2012, 11:23 AM
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Location: greenwood, IN
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Re: Concentricity Gauge

Quote:
Originally Posted by Brno308 View Post
Handloader1, thanks for the suggestion. Is there a sure fire method of squaring dies or should I go with the rubber O ring method. All input is appreciated.
Kinda depends on the style of press you use as to how you square the dies, but in the end it all comes out the same. With a Forster you simply loosen the lock ring, and put the die under good pressure. I use a square block of steel that I know is extremely square, but have done this with a case in the die as well. I prefer the block method. With a conventional press your pretty much locked into running a case thru the die under pressure and then tighten the jam nut. Problem with that is in making adjustments (actually both methods). Quite honestly I don't have a favorite way to do this as none have completely satisfied me. Just too many variables, and no way to take most of them out. Then to add insult to injury, you get your die so square that it ought to be gold plated, and you get a tight case. Back to square one again

It's Tuesday, and I'm long over due for a rant!
gary
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  #17  
Old 12-12-2012, 07:49 PM
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Join Date: Oct 2006
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Re: Concentricity Gauge

I have the Sinclair concentricity gauge.
I don't use it much, but I do a lot of things based on what I learned from using it.

A) The expander ball [pulling] used in the same step as FL sizing with FL die [in original configuration with neck not honed out] can bend the necks so bad that all other sins pale in comparison.

FL sizing with the same die with the expander ball removed, and then using expander ball [pushing ] in a separate step makes only 1/4 as much neck bending.

B Dies matter
1) Redding FL "S" dies cost the most and look the best, but are the worst for concentricity.

2) Forster FL dies with the neck honed out at the factory to my spec is in the middle.

3) Lee collet neck dies cost the least, look the worst, but make the best for concentricity.

C) Chambers matter
A tight neck no turn reamer is much better than a loose neck chamber made with a SAAMI reamer.

D) Brass matters.
How the S die bends necks is that it floats toward the side of the neck with thicker walls.
Lots of long range matches are won with unturned necks, but they sort for low run out in thickness.

Turning brass on the lathe takes skill. Sometimes I get .0001" and sometimes .0010"
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  #18  
Old 12-12-2012, 09:42 PM
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Join Date: Sep 2012
Posts: 41
Re: Concentricity Gauge

Brno308:

I have always used the washer method; here is a link which explains the procedure scroll down near the bottom >> exterior ballistics . Good luck.
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  #19  
Old 12-13-2012, 11:40 AM
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Join Date: Jun 2010
Location: greenwood, IN
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Re: Concentricity Gauge

Quote:
Originally Posted by Clark View Post
I have the Sinclair concentricity gauge.
I don't use it much, but I do a lot of things based on what I learned from using it.

A) The expander ball [pulling] used in the same step as FL sizing with FL die [in original configuration with neck not honed out] can bend the necks so bad that all other sins pale in comparison.

FL sizing with the same die with the expander ball removed, and then using expander ball [pushing ] in a separate step makes only 1/4 as much neck bending.

B Dies matter
1) Redding FL "S" dies cost the most and look the best, but are the worst for concentricity.

2) Forster FL dies with the neck honed out at the factory to my spec is in the middle.

3) Lee collet neck dies cost the least, look the worst, but make the best for concentricity.

C) Chambers matter
A tight neck no turn reamer is much better than a loose neck chamber made with a SAAMI reamer.

D) Brass matters.
How the S die bends necks is that it floats toward the side of the neck with thicker walls.
Lots of long range matches are won with unturned necks, but they sort for low run out in thickness.

Turning brass on the lathe takes skill. Sometimes I get .0001" and sometimes .0010"
I can't get anything round with the Lee collet dies, and that bugs me to death. Perhaps with different brass, or maybe mine are just on the big side.

The Forster full length die has always just been a few tenths behind the Wilson dies at my house. I get very concentric necks with them.

I turn necks with a Sinclair neck turning tool (have two). Not my favorite by a long shot, but also all that I have. Once I get the diameter I'm after it seems to repeat very consistently. I rough turn with one tool and finish with the other (removing about .002" on the finish). What I don't like about it is that the cut follows the mandrel, and the mandrel has to have some clearence. I'm thinking about trying the Wilson outside neck turner in the near future
gary
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  #20  
Old 12-13-2012, 05:00 PM
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Join Date: Oct 2006
Posts: 455
Re: Concentricity Gauge

The Lee Collet neck dies must be adjusted.
A big advantage for them with unturned necks is that the inside diameter of the neck is what ends up concentric, not the outside diameter.

~ 10 years ago I broke an RCBS rockchucker with a Lee Collet neck die adjusted to make the press just cam over at 100 pounds force on the knob. That makes infinite internal force, minus friction, in the press.
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  #21  
Old 12-14-2012, 11:33 AM
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Join Date: Jun 2010
Location: greenwood, IN
Posts: 3,546
Re: Concentricity Gauge

Quote:
Originally Posted by Clark View Post
The Lee Collet neck dies must be adjusted.
A big advantage for them with unturned necks is that the inside diameter of the neck is what ends up concentric, not the outside diameter.

~ 10 years ago I broke an RCBS rockchucker with a Lee Collet neck die adjusted to make the press just cam over at 100 pounds force on the knob. That makes infinite internal force, minus friction, in the press.
you may have answered the question about not getting round necks. I'm having to crank the collet down to the extreme to get what I want, and then it's not round due to the collet being over stressed. But just as bad is that if you check the case body on a shadowgraph you will see ridges that run parallel to the centerline of the case. Kinda tells me that the collet I.D.'s are a few thousandths oversize.
gary
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