338 Mollett said:Good idea Eric,with the V block you can slide the bullet any where and measure it.Make a stop and measure base to ogive even.
amlevin said:338 Mollett said:Good idea Eric,with the V block you can slide the bullet any where and measure it.Make a stop and measure base to ogive even.
Add to the tool a precision ground cylinder that's the same diameter of the bullet (as designed). Put this "standard" in the v-block and zero the dial indicator. Then measure the bullet. Results will show as amount over or under the nominal bullet size.
Maybe a turning mandrel in a custom diameter for a quick, easy, and precision "standard".
jlow said:For that, you will have to take at least three measurements around its circumference using the micrometer.
jlow said:Using a gauge like what the OP is describing, I can envision an undersized bullet that is elipical in cross-section fitting perfectly through the optimal diameter gauge and the operator not knowing it is happening…. THAT is what I don't like about this idea of a go/no go gauge.
There used to be an example at a place I worked in the lab. Had a shaft ground to 1.3748 minus .0005. Measuring with a two point mic would get 1.3740 in three places and looked round but under. The part was not even close to fitting through a 1.375 ring gage. Wouldn't even start. Vee block and indicator showed multiple lobes and scanning on the cmm showed 5 distinct lobes with an extreme diameter of 1.376. Very eye opening for choosing the proper tool to measure. Form of shafts and holes are one of the hardest.
LRPV said:I'm ignorant as could be when it comes to all of this precision measuring you guys are talking about but I would like to try something like the op proposed. My thinking would be something similar to a neck bushing made from carbide but maybe it wouldn't be feasible.