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Measuring a reamer shoulder angle
- Thread starter Ksracer
- Start date
- Replies 11
- Views 2,325
You don't need a tenth indicator. Your compound is graduated in .001 increments, right? Then that is , at best , your resolution. Introducing a different resolution in a different direction will not improve that and will drive you crazy with the uncertainty that it will introduce.
Yes, measure the sine of the angle and the length. Then a calculator will tell you close enough. It isn't that critical anyway. Once the primer ignites they all conform to the chamber wall.
Yes, measure the sine of the angle and the length. Then a calculator will tell you close enough. It isn't that critical anyway. Once the primer ignites they all conform to the chamber wall.
johnoder
Diamond
- Joined
- Jul 16, 2004
- Location
- Houston, TX USA
Or in different words - there is a large diameter, an adjacent smaller diameter and a length along the bed ways.
The small dia subtracted from the large and divided by two gives one side of the triangle and the length along the bed ways gives a second side of the triangle
Manipulating these two values thru a calculator (or a cad program) will give you either an angle off center line or its complement
The small dia subtracted from the large and divided by two gives one side of the triangle and the length along the bed ways gives a second side of the triangle
Manipulating these two values thru a calculator (or a cad program) will give you either an angle off center line or its complement
Ok, thanks. That's probably a more accurate way. I was simply going to swing the compound until I could trace the angle with the indicator, and then read the degrees on the compound base. I'll try both methods and see if the answers agree.
The issue I'm having is that resized brass headspaces on the neck-shoulder junction, not the face of the shoulder. I beleive my reamer was cut to 30deg and the dies 31deg. It's a 6CompMatch, just FYI.
The issue I'm having is that resized brass headspaces on the neck-shoulder junction, not the face of the shoulder. I beleive my reamer was cut to 30deg and the dies 31deg. It's a 6CompMatch, just FYI.
michiganbuck
Diamond
- Joined
- Jun 28, 2012
- Location
- Mt Clemens, Michigan 48035
Having a sine bar you might attach the reamer long way.. then (Jo Block) build up the sine to get zero/zero on the angle with a test indicator.
But with not being able to roll the reamer under the indicator this would be some off.
But with not being able to roll the reamer under the indicator this would be some off.
I'm using bushing type dies, resizing brass that was cream of wheat fireformed in a different barrel cut for that purpose only. The bushing type dies may not even be resizing the neck-shoulder junction.... This is exactly what I plan on investigating next after I verify the angle. Thanks.
Just an update. I mounted the reamer between centers and swung the compound to 31deg and traced the shoulder. I had roughly a half-thousandth deviation. Then I ran the crosslide in until the indicator read '0' on the big diameter and zero'd the handweel. I moved the carriage .100" to the small diameter and ran the crosslide in until the indicator again showed '0'. The handwheel was now at .0595. .100÷.0595=1.681 The tangent of 1.681 is 30deg and 45min. I'd say the reamer has the correct angle. Thanks for the help!
Paolo_MD
Stainless
- Joined
- Apr 6, 2013
- Location
- Damascus, MD
Honestly, I'm a bit confused: you went through the hassle of having a different barrel to fireform your brass. I would expect that the chambers in the two barrels to be cut with the same reamer without any re-sharpening in between. Otherwise, the whole setup doesn't make any sense to me.
Paolo
akajun
Stainless
- Joined
- Jul 1, 2011
- Location
- Brusly, LA
You are getting what called a doughnut from your bushing die, it's not an uncommon problem with some bushing dies. Read up on accurate shooter on how to fix it.
Thanks, I'll do some reading on that later, it sounds very similar to my issue. The die I have isn't a good match on body diameter to my chamber, so I mailed off some fired brass to Widden today so they can make me a non-bushing die. I'm guessing it fixes my issue.
akajun
Stainless
- Joined
- Jul 1, 2011
- Location
- Brusly, LA
Yep that's the best way, John knows his business. Many people think Dounuts only form on the inside of the neck but they can form on the outside too.
