ntsqd
Well-Known Member
The new tool that started this is a Mitutoyo digital micrometer with resolution to .00005" To me that last digit is the round-off direction, not an actual size measurement; if it is 0 then I round low, if it is a 5 then I round high. The other tool is a Porter Precision Products expander mandrel system. Porter sells the pins in two sizes for each caliber and I bought both sizes for each since I don't yet know what I'm going to want for neck tension. My thanks to whomever it was that posted a link to their page a while back, truly impressed with the product & wish that I had known about it before buying the Sinclair system.
That said, out of curiosity as to what diameter they actually are and to try out the new mic than anything else I mic'd a couple of the Sinclair TiN coated expander mandrels. I found them to vary in diameter by as much as .0005" I really wasn't expecting that. I guess the question is, is a .0005" out of round acceptable?
So then I mic'd some of the gauge pins that came with the Porter expander mandrel system and I got the same exact reading each place that I measured any of those pins. If the pin was marked ".223+" and I got .22305" in one location, I got ".22305" in all locations that I measured on that pin. I really would expect that given what gauge pins are normally used for.
That said, out of curiosity as to what diameter they actually are and to try out the new mic than anything else I mic'd a couple of the Sinclair TiN coated expander mandrels. I found them to vary in diameter by as much as .0005" I really wasn't expecting that. I guess the question is, is a .0005" out of round acceptable?
So then I mic'd some of the gauge pins that came with the Porter expander mandrel system and I got the same exact reading each place that I measured any of those pins. If the pin was marked ".223+" and I got .22305" in one location, I got ".22305" in all locations that I measured on that pin. I really would expect that given what gauge pins are normally used for.