Robin S. wrote:
"Jim Stewart" wrote in message
.. .



I noticed that in order to get them to wring
together, the surfaces had to be close to
perfectly clean. I assume they have to be
re-oiled after use.


I usually wipe the working surfaces on a clean sheet of paper. I've found
the wring the best using this simple cleaning process. Laying the paper on a
clean surface plate does an excellent job.

While I've heard paper is abrasive, I'd be surprised if you could actually
do any damage to the blocks (just in case anyone wants to object). The gauge
blocks at work are subject to an environment rife with abrasive dust, as
well as what some would call abusive use, and they still wring.

I can speak somewhat authoritatively on the
subject of paper, having served as project
manager designing high speed ballot counters.

As trees grow, silica matter is picked up
from the soil and gets tightly embedded into
the cellular structure of the tree. The silica
stays there even through normal paper production.

A piece of mild steel or AL, pressed against
quickly moving paper, can have thousandths
sanded off in a surprisingly short time. Likewise,
a glass window will get scored quickly.

Whether one or two swipes with a gauge block
would do any damage over the life of the blocks,
I don't know. I'd probably not do it if I
were using the blocks frequently.

Does anyone know what the accepted procedure
is for testing mikes and calipers? Some
sort of progression of blocks that serves
as a worst-case test?


Those gauges that Peter mentioned are pretty neat. I have to ask though, are
you doing work that will hinge on the last .0001" or so of your mic's
accuracy? Seems excessive unless the mic you're checking is very old or well
used.

No, not at all. What I'm more interested in is
whether or not my import calipers are reading
right over their full length of travel. The
calipers only have to be accurate to a couple
thousandths for my work. Lenny's advice of staying
away from even intervals is probably all I need
to do.