shims

[richard bies <bies@infobahn.icubed.com>]

Before we leave this thread, let us assume the person has no experience
with micrometers, buys one, extracts the offending shim, and sets-out to
measure it, expecting a precise result to fall-out unambiguously....

And then he finds he can vary the measured thickness by several thousanths
depending on how tight he turns the barrel......

It takes practice with known standards, or experience to read the damned
thing even to one thousanth.  The small diameter knurled end is what one
is supposed to tighten with (not the larger barrel).  But it is the
difference which counts -- tighten on the offending shim and on the
proposed replacement to the same pressure -- the <difference> in readings 
should make-up the discrepancy noted in checking the clearance (the
distinction between <accuracy> and <precision> -- how thick either shim
actually is is of no consequence, but the replacement must precisely
compensate for the noted discrepancy).

r.m.bies