Re: [CAD_CAM_EDM_DRO] Re: Simple DRO sensors - Cheap !

> > > They also cary linear encoder strip, but making protective housings is
> > > a real pain.
>
> > Wouldn't these be the best choice for accuracy? It seems to me using data
> > from a linear strip would eliminate the problems arising from
> > ballscrew/leadscrew tolerances, or rather would allow the software to
> > compensate for it in a way that a rotary encoder couldn't.
> >

Yes, glass scales are very good. unfortunately, these are Mylar film, and Mylar
has a HUGE humidity coefficient of expansion, as well as a large (compared to
glass or steel) thermal coefficient. Accumulate several feet of expansion, and
it could be quite an error buildup.

>
> > My concern though is that "CPI" resolution... the highest was 360, does this
> > mean it would only read to 1/360 = 0.00277..... inch? As even low end
> > ballscrews have runouts around 0.004", it wouldn't seem to be much of an
> > improvement, if that is the case.

In quadrature, it is 4 x 360 or 1440 counts/inch = 0.0006944" per count.
The CPI they refer to is Cycles per Inch of the black/clear pattern.

Jon