Caliper technique - Page 2

F. Guffey · May 4, 2011, 07:02 AM

I will recuse myself, I do not belong in this discussion, no mention of standards, transfers etc., etc.. the companion tool to the press, the feeler gage and another tool/transfer/gage/standard, a/the parallel, for those that use light to measure a gap, use light, me? I use the feeler gage.

And as I said before, I took a picture of my gages and micrometers, the picture weighed 400 + lbs.

F. Guffey

wncchester · May 4, 2011, 08:21 AM

Jim243: "Wncchester, now what rifle case is 12 inches long? (LOL) I knew you were loading some strange stuff, but 30mm rounds?(LOL) (just joking)"

I wasn't joking but I was a bit 'tongue in cheek' when addressing the idea that we can do much real measureing without a micrometer. Not all reloaders have a micrometer at all and most of those who do only have a 1" model. I do have a 2" mic but even it's too small to do much in reloading so I laffingly used the 12" caliper example you quote, it's very handy for checking the OAL of a 20mm round.

Don P · May 4, 2011, 01:00 PM

Quote:

Calipers are always more accurate deepest it the jaws (less play).

If the above is happening then a new caliper is needed. No one should be trying to apply that much pressure to a item being measured to obtain "play". My caliper will only tighten so much then it stops.
Quality calipers will not perform as stated in the quote.

As a side thought, is .001 going to make the world collapse with regards to case length

Inspector3711 · May 4, 2011, 01:33 PM

Quote:

If anyone is checking aircraft parts with the tips of calipers, I don’t want to be on that plane. Real precision requires the use of micrometers, indicators or electronic measuring equipment

Written like someone who doesn't know much about aircraft.

I'll try not to be offended here.. I have 25 years of aerospace experience. I work for what is arguably the finest aircraft company in the world and have reached the pinnacle of being at the highest level (FAA Coordinator in the Test Division) as an inspector in a work force of 150,000+. I also have 10 years as an FAA inspector on my resume.

I'm probably familiar with at least the level of precision you are, having inspected everything from hydraulic cylinders and turbine blades to close tolerance holes in a fuel pump.

The drawing tolerance dictates what equipment is used to measure the part feature. That tolerance can be +/- .0015" or +/-.200", and I can run across both in the same day.

On any given job I'll use a 6" scale, a micrometer, a million dollar CMM, or a set of calipers. Not everything on an aircraft has a tight tolerance. How much would carpet cost if we measured it with a CMM?

Greg Mercurio · May 4, 2011, 03:01 PM

Inspector3711: Well stated!

Mike / Tx · May 5, 2011, 05:08 AM

Like has been stated the user can influence the reading to some degree. The ideal situation is to develop a feel for measure things and keep fresh with it. Myself, I use the fat part of the blade just behind the tips, with the outermost portion of the case head setting right against where the blade starts to thin. As mentioned it gives a nice flat base so that the case can be held securely in place for a repeatable measurement.

I started my work career off to be a machinist, but due to the economy at the time I moved into the industrial mechanical field as a millwright. As such the facility where I have worked for close to 30 year at, required the parts I inspect, and draw up to be machined or replaced, to be accurately measured. To some degree there are tolerances built into everything, just like in reloading ammunition for specific firearms. There is a SAMME "standard" by which things are specified, but these are only a standard and folks adjust them to their specific needs.

May 4, 2011, 07:02 AM	#26
F. Guffey Senior Member Join Date: July 18, 2008 Posts: 7,249	I will recuse myself, I do not belong in this discussion, no mention of standards, transfers etc., etc.. the companion tool to the press, the feeler gage and another tool/transfer/gage/standard, a/the parallel, for those that use light to measure a gap, use light, me? I use the feeler gage. And as I said before, I took a picture of my gages and micrometers, the picture weighed 400 + lbs. F. Guffey

May 4, 2011, 08:21 AM	#27
wncchester Senior Member Join Date: December 1, 2002 Posts: 2,832	Jim243: "Wncchester, now what rifle case is 12 inches long? (LOL) I knew you were loading some strange stuff, but 30mm rounds?(LOL) (just joking)" I wasn't joking but I was a bit 'tongue in cheek' when addressing the idea that we can do much real measureing without a micrometer. Not all reloaders have a micrometer at all and most of those who do only have a 1" model. I do have a 2" mic but even it's too small to do much in reloading so I laffingly used the 12" caliper example you quote, it's very handy for checking the OAL of a 20mm round.

May 4, 2011, 03:01 PM	#30
Greg Mercurio Senior Member Join Date: December 5, 2010 Posts: 151	Inspector3711: Well stated!

May 5, 2011, 05:08 AM	#31
Mike / Tx Senior Member Join Date: April 8, 2000 Posts: 2,101	Like has been stated the user can influence the reading to some degree. The ideal situation is to develop a feel for measure things and keep fresh with it. Myself, I use the fat part of the blade just behind the tips, with the outermost portion of the case head setting right against where the blade starts to thin. As mentioned it gives a nice flat base so that the case can be held securely in place for a repeatable measurement. I started my work career off to be a machinist, but due to the economy at the time I moved into the industrial mechanical field as a millwright. As such the facility where I have worked for close to 30 year at, required the parts I inspect, and draw up to be machined or replaced, to be accurately measured. To some degree there are tolerances built into everything, just like in reloading ammunition for specific firearms. There is a SAMME "standard" by which things are specified, but these are only a standard and folks adjust them to their specific needs.