"Ernest Christley" wrote in message m...
: RST Engineering wrote:
::
: I *BEG* your pardon? In my part of the world, 0.0 is within 50 mils, 0.00
: within 20 mils and 0.000 within 5 mils.
:
:
: I have only a couple measurements on my set of plans that call for a
: specific tolerance. One is for the pins locking the gear leg halves
: together. The other is for the wing lock pin. The rest are just
: measurements with the smallest being with 1/16". Everything broken down
: into feet, inches and fractional inches. But no "plus or minus"
: anywhere. So I asked a recently retired machine shopman and sheetmetal
: worker, because, heh, if you can't trust somebody that's been doing it
: 40yrs, who can you trust? He told me 1/32" if not specified. Does the
: difference come down to how the numbers are specified? Fractional
: inches resolve to 1/32, and decimal inches have the tolerances you state?

Where I work , unless otherwise stated, we tolerance to:
Fractions ±1/64
0.0 ± 0.010 (10 mils)
0.00 ± 0.005 (5 mils)
0.000 ± 0.001 (1 mil)
We do make assemblies where we hold clearances of 50 micro-inches (µin) (Oh no, not another one!)