Re: Knuth DRO's from Singapore on EBAY - has anyone bought them?

Hi Jon,

Thanks for the head's up on the scales. The .0001 that I was quoting
was based on their stated specs. But even if it were worse than that,
it would be fine by me. The only off-the-shelf alternative in the
price range is the Shooting Star system, which sounds like people are
using and happy with, is .0005.

Based on the comments, I guess nobody here has dealt with this company
so it's a crap-shoot.

Thanks again,
Ted

--- In CAD_CAM_EDM_DRO@yahoogroups.com, Jon Elson <elson@p...> wrote:
>
>
> Ted Inoue wrote:
>
> >I've recently stumbled across the following EBAY ad:
> >item number 2570941080
> >
> >They have 2 and 3 axis, Knuth DRO units with glass scales, rated at
> >0.0001".
> >Looks like a decent unit and the prices can't be beat for the
> >features. $549 for 2 axis, $779 for 3 axis, plus $88 shipping
charges.
> >
> >
> Note that just because the readout DISPLAYS 4 digits to the right
> of the decimal point does not mean it actually has that resolution.
>
> People in the industry have told me than nobody makes actual
Imperial
> (Inch) scales since the late 1960s! So, all the scales are actually
metric,
> and they do a conversion to inches in the readout box. Unless you
pay
> a fortune, the best scales you can get are typically 5 uM, which
gives
> a resolution of roughly 0.0001969". That is about .0002", but not
> EXACTLY .0002". Therefore, if you fiddle with one for a bit, you
> will find there are certain readings you CAN'T get to! This drives
some
> Inch-bound machinist slightly batty.
>
> Jon