"CAMCOMPCO" wrote in message
ups.com...
Hi Dave,

Not following ya here. I have purchased precision Brown and Sharp
1-2-3 blocks, they all read, 1-2-3 to the 1.000 with the last +/-
0.0005 stuck on zero. I have found that the secret to using calipers
is to wiggle them into the product you are measuring while you apply a
bit of pressure (light) on it, take the smallest reading you get, and
that is the diameter. Now, i am not a machinist, won't be for 20 more
years I imagine, so no argument intended here, just don't follow ya.
Wouldn't I expect to get variance from 1.000 on any of the "Chinese"
calipers if they weren't as accurate as they are stated to be? Not
talking tenths here, just the stated "round to the nearest 0.0005".


You actually are talking tenths. If a drawing specifies +/-.001", a measured
dimension of +.0011 is out of tolerance. Obviously if your calipers read to
only five tenths, they'd probably tell you +.001" which would be wrong.

Ideally, your measuring instrument should be ten times more accurate than
the tolerance it's evaluating. Sometimes this will drop to between two and
five, depending on the actual tolerance, method of measurement, speed, etc.,
etc., etc.

Regards,

Robin