I have just bought myself a new digital micrometer, it's this one here
from pvrdirect:-

http://www.pvrdirect.co.uk/productin...s&catref=52426

I'm not sure if it's supposed to have instructions with it, but it
doesn't, and the link to instructions from the above web page is broken.

The last time I used a micrometer was at school (a *very* long time
ago!). I know the basics and have made the measurements I bought it
for OK but there are a couple of things I can't work out.

What's the little lever above and left of the digital read out
for? Ah, I think I've worked it out, it clamps the reading so one
can measure something inaccessible, clamp the reading and then
withdraw the micrometer to actually see the reading.

I can't quite work out the action of the ratchet knob. It's OK
for getting correct/reasonable pressure on the measured object,
rotate with the knob on the end and just wind until it clicks.
However I think it usually does something for mechanical zeroing
as well but all I can make it do is the ratcet action and, if I
hold the main knurled ring and unscrew the end one it just
unscrews, it doesn't seem to allow mechanical zeroing.

There is a strange little 'hooky spanner' sort of tool comes with
the micrometer. It latches into holes on the large round bit and
the small round bit (just inside the knurling). Presumably it
allows on to rotate/unscrew these but why would one want to? Is
*this* for machanical zeroing?

--
Chris Green