Re: Digitizers, Renishaw

Hi Fred,

Thanks for the comments. I can't afford one either, but did you read
the post from Peter? Not THAT sounds like something we could make! If
we scan like we are cutting cross sections, then I think we'd have
contours to cut. We might be able to generate "scan contours" in
vector, and then the output points would be arranged in contours... I
think.

Fred Smith wrote:

>
> --- In CAD_CAM_EDM_DRO@egroups.com, Alan Marconett KM6VV <KM6VV@a...>
> wrote:
> >Hope this makes some sense. Any other ideas? I'd love to
> > watch a digitizer program run!
> >
>
> I had a chance to play with some Picza files a couple of years ago.
> I was trying to import the scanned files into Bobcad or Vector and
> then do something useful with them. The files were DXF 3D face
> entities. I wrote a VB program to translate them into a series of
> cross sections, in the X-Z plane. The cross sections were planar &
> either Bobcad or Vector could apply an offset curve to the contour so
> that it could be cut with a cutter of any desired size.
>
> MicroKinetics has a command G26 that makes a conditional branch,
> based on some switch setting.
>
> Flashcut has an M100 that sppears to be similar.
>
> You could probably even use the axis limit switch sensing to control
> the probe contact.

Getting a switch contact read is not hard, but I have not seen any Gcode
words that would save a data point to a file.

>
> A good setup to me would be to use one of these digital indicators
> with an Spc output. If you had one with say a sizable range, you
> could calibrate at full depth against the table=0 say , then pick up
> the Z axis, position to a defined place on a grid, and move the head
> down to the zeroing Z height, that would zero out the indicator if
> there was no contact, or record some vertical displacement if the
> object being measured was contacted. Pause at this depth until the
> measurement is recorded, then use a macro to continue to the next
> position. Sony makes a 2.36" travel digital indicator with .00005
> resolution and RS-232 that is available from MSC for about $500. I
> expect that this would be a more reliable solution than the MaxNC
> probe which some have complained about the quality.

Wouldn't the digital indicator still be a single axis of motion? OK if
you control the approach (rotary table?), but a lot of work. I'll bet a
clock maker could replace the needle of a "Last Word" dial test
indicator with an encoder disk, and then we'd have something similar. I
need a dial test indicator first!

Alan KM6VV

>
> >
> > Found a site for Renishaw, I dare not ask the price:
> >
>
> MSC has them for $3000-$8000, Fowler has one for about $1000. Out of
> my price range.
>
> Best Regards,
>
> Fred Smith
> IMService