"Mechanical Magic" wrote in message
...
snip----

Where I disagree: measuring a smallish hole with calipers. To suggest
that +-.005" is to be expected, is leading the inexperienced down the
wrong path. I have tried all my calipers with a .2000" ring, and they
ALL read a smaller diameter, by different amounts. I don't believe a
hole measurement to within .010"

Dave

Grin!

I was trying to avoid an ugly confrontation with those the seem to think
that a caliper, particularly a digital, is the ultimate in precision. I've
had conversations with such individuals, and they rarely will be denied
their opinion. What fools they are. I have used a decent scale
(Starrett C305R) with as much precision as I've achieved with calipers.
I use them only when it clearly does not matter. They're great for checking
the size of raw stock.

I got baptism by fire, violating my own rules of not trusting a caliper.
Some time ago, I purchased a Wilson Rockwell hardness tester off ebay. Got
it right, but it had no weights, and had to make new lenses for the
indicator and its cover because they had been warped. Looks like the
instrument had been stored in a hot location, or it had been in the
proximity of a fire, although with no fire or water damage.

I have a fair amount of 4" diameter 304 stainless, a material that I do not
enjoy machining. I knew I'd likely never choose it for a project, so using
some of it for making the weights was a great idea. The design is one of
my own creation, although similar to that of the original maker. I
wanted a counterbore to fit a shouldered turn, so when the weights were
stacked in use, they'd be fairly concentric, and remain on center as they
should. I used an old Helios caliper I've owned since late '57. I know
damned well they aren't perfect, but figured I could use a little Kentucky
windage and achieve a loose slip fit. That's what I got-----but too
loose. I would have been pleased with two or three thou----but had to live
with ten.

Will I ever learn? :-(

Harold