Re: [CAD_CAM_EDM_DRO] Re: Easy DRO For Lathe

totallyrc wrote:

> --- In CAD_CAM_EDM_DRO@yahoogroups.com, "Jim Reed" <jsreed@...> wrote:
>
>>Look up wiki.linuxcnc.org/cgi-bin/emcinfo.pl?PyVCP . It has a 3
>
> axis

SNIP

>>
>>>Best regards
>>>Kris
>>>
>>
> A roller type I believe is how my SWI dro works on my mill. It
> bassically has a rubber? wheel which rides on the flat surface of the
> table and has an encoder connected to it, as opposed to a rack and
> pinion or a glass scale.
> The roller type is great for inexpensive machines as I would assume
> that it will not hold position after many cycles back and forth, but
> for Joe average, who does 3 or 4 pieces and then changes setup, it
> works out real well.
>
> Mike

The roller is hardened steel wheel with a radius on the OD and tiny
grooves ground around this radius. The radius is to let you tilt the
reader head up or down to change the efective diameter of the roller so
you can calibrate it, the grooves roll a tiny "gear rack" into the
surface it runs against. After the head has been traversed a number of
times the readout will give very consistant readings. I have one on the
Z of a manual lathe and have not seen it drift at all with many
traverses. I have a small HBM with them on three axis and it also
repeats. Ed.