Re: [CAD_CAM_EDM_DRO] Re: low cost linear encoders

Hi,

At a slight tangent to these discussions, does anyone know how the Mitutoyo
digital vernier works? Mine has a bit of the scale torn off at the very end
and under it appears to be a length of something like printed circuit board
with diagonal cuts across it. I assume they must use some form of quadrature
sensing on these copper parallelograms but I can't think of either how they
would sense the presence or absence of copper without touching it (it's
under the thin plastic adhesive scale) or how they would get the required
resolution of better than .0001" with something which seems so crudely made.
Perhaps this method could be adapted for our linear DROs? Making the linear
strip would seem to be quite possible in the home shop, probably by making
an indexing jig with a guide for a knife to cut the copper of thin PCB, and
the fact that it is a non-contact method which is also non-optical should
mean that it would be relatively immune to the mess around a machine -
certainly my vernier seems to work OK in such an environment as it is
usually lying under a pile of muck in the lathe drip tray and I have to wipe
it off each time I want to use it (This one's only my rough measurer which
cost me the princely sum of 5UKP at a boot sale - my other tools get treated
better!)

Ian

--
Ian W. Wright
Sheffield UK

----- Original Message -----
From: Bill Phillips <cad@...>
To: <CAD_CAM_EDM_DRO@onelist.com>
Sent: 15 March 2000 21:27
Subject: Re: [CAD_CAM_EDM_DRO] Re: low cost linear encoders


> From: Bill Phillips <cad@...>
>
> >> From: stratton@...
> >>
> >> > several people have asked for higher resolution encoder strips
> >> > for similar purpose as the US Digital strips. I just got a magazine