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