0.028...lemme see now...
divide by 25.4, multiply by something um...
0.7mm? um? thats a standard plug gap...
or 0.07? arrrrg!
you know i refuse to follow any plans that are measured in that horrible unit, though i always found it amusing to call a 4x2 a "3 35/64 x 1 49/64"...(finished size is 90x45 over here...)
the number of customers that were amazed i could use both units (when i worked in a timber yard) was astonishing. but thou just hurts my head... even if my lathe is imperial, i hate it hate it hate it! ever tried cutting metric threads on an imperial lathe? you cant take it out of gear! forwards, stop, backwards, stop, forget to back tool off, snap, regrind tool, re-align tool, snap, repeat process, give up and wait two weeks for a weird sized die to arrive off e-bay... M9x1? wtf?
nope, i still say as long as its about the same as a credit card is thick...its fine. never had an issue.
have burnt plenty of ignition coils out by going over 2mm though...