[Shop-talk] Micrometers

[David Scheidt]

On Sun, Nov 1, 2009 at 7:56 AM, Arvid Jedlicka <arvidj at visi.com> wrote:

> Looking at your diagram, I disagee that 'A' must equal 'B'.
>
> Assuming you can 'zero' the caliper when the two 'B' jaws are together then
> the measurements should be as accurate as when you 'zero' the caliper when
> the two 'A' jaws are together and take a measurement.
>
> Note that this is different than saying "when the 'B' jaws are together
> then the 'A' jaws must also be together", which is what I think you are
> after.
>
>
Any caliper where this isn't true is junk.  It's true even on my insanely
cheap plastic calipers that I keep in the pen jar on my desk.  Same for the
depth probe.  Think about it.  Vernier calipers have no way to zero them.
All three measurements are read from the same scale.  So if one says zero,
they all should be at zero.  anything else is an inaccurate measure.