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Thread: Lapping on dies

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  1. #1
    Join Date
    May 2015
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    Lapping on dies

    I have a Redding SB 6ppc die that sizes the base area about .0015 squeeze but the shoulder/body junction is .003 sized down. Id like .0005 squeeze up there and .001 at base. Is there any slick trick lapping/polishing that would make it more betterer? Maybe .003 is ok?? Seems a lot.

    Wally

  2. #2
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    If you have a lathe, you can use 250 grit Emory paper on a piece of round stock. It will cut the case hardened die. It will take a while, and you need to concentrate on the shoulder end to take more out in that area.

  3. #3
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    I had someone who has been well known for die work open up the shoulder of a PPC die and when I got it back, with a $60 bill that I paid, it was effectively ruined because of the runout of the sized cases. This was a long time ago, but based on that I think that I would stick with opening up the back of a die, or possibly the neck of a one piece die, but evidently working so close to the point of the shoulder involves more risk of failure.

  4. #4
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    Quote Originally Posted by jackie schmidt View Post
    If you have a lathe, you can use 250 grit Emory paper on a piece of round stock. It will cut the case hardened die. It will take a while, and you need to concentrate on the shoulder end to take more out in that area.
    For best results use a Silicon Carbide abrasive. An Emory abrasive is way too soft for steel.

    .

  5. #5
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    Quote Originally Posted by WallyDog View Post
    I have a Redding SB 6ppc die that sizes the base area about .0015 squeeze but the shoulder/body junction is .003 sized down. Id like .0005 squeeze up there and .001 at base. Is there any slick trick lapping/polishing that would make it more betterer? Maybe .003 is ok?? Seems a lot. Wally
    Wally, I'm an 'aggressive sizer' when it comes to the shoulder/body junction.....especially on cases with 30 degree and greater shoulder angles. For me, .002 would be the minimum and .003 would be perfect. -Al

  6. #6
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    May 2015
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    Makes sense !

    Quote Originally Posted by Al Nyhus View Post
    Wally, I'm an 'aggressive sizer' when it comes to the shoulder/body junction.....especially on cases with 30 degree and greater shoulder angles. For me, .002 would be the minimum and .003 would be perfect. -Al
    Since its a diameter we are actually talking .0015 clearance per side. Thats the size of my gray thinning hair. Talked me into it Al!

  7. #7
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    Quote Originally Posted by WallyDog View Post
    Since its a diameter we are actually talking .0015 clearance per side. Thats the size of my gray thinning hair. Talked me into it Al!
    Laffin', here! -Al

    P.S. The average diameter of a human scalp hair is .004, so you're waaaay safe.
    Last edited by Al Nyhus; 08-28-2020 at 11:49 AM.

  8. #8
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    Jun 2010
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    USA
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    AL, bring that pesky die down, and we'll lap it to within 0.000005", or, we'll have HIM buy U, "uh nu un". RG

  9. #9
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    Quote Originally Posted by R.G. Robinett View Post
    AL, bring that pesky die down, and we'll lap it to within 0.000005", or, we'll have HIM buy U, "uh nu un". RG
    Randy, I'm hackin' and slashing away at this hunk of steel trying to make something out of it that will squeeze a piece of brass to where I think it needs to go. A real machinist or a talented-type like yourself would either laugh or cry if you were to witness the carnage.

    Every time I fire up the lathe or mill, I'd swear John Wayne talks to me. Maybe He has taken up residence in some dark corner of the shop?

    Last edited by Al Nyhus; 08-28-2020 at 07:54 PM.

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