Re: [CAD_CAM_EDM_DRO] Re: Re: Digitizers, Renishaw (for bill phillips)

Hi Ballendo
I have no idea how the Roland probe works but have often wondered along
similar lines. All the probes I have heard of using piezo's were passive.
The piezo acting more like a strain gauge.
Conventional probes use a rigid stylus with a very hard tip, with the
sensor buried away in the probe body. Seems to me that some kind of sensor
on the tip which could detect a touch might be capable of very good
accuracy. However I am dreaming because :
Piezo's have rotten temperature and moisture stability. (need frequent
calibration)
The wiggle would need to be in 3D, unless you are only going to probe in
one dimension.
The wiggle will set up resonances and vibrations in the structure that will
need to be filtered out. I would expect that a DSP chip to filter the
signal and some very careful mechanical design would be required.
Just to throw another wobbly. What about different surface textures,
cleanliness of the part, vibration from the machine etc.

Of course I may be being too pesimistic, if your are prepared to accept
sensible accuracy levels it may just work. Any idea what accuracy Roland
claim?

Any idea where small piezo's might be unearthed from? I would guess the
smallest buzzer I have would be around 10mm diam. Too big for a probe tip.

Regards
Bill Phillips

>Since you're here :-)
>What are your thoughts re: "the piezio being used to 'wiggle the
>probe', watch for freq. shift on contact" technique that roland
>appears to use? I can see ways to easily overcome the issues noted
>above. What am I missing?
>
>Thank you in advance.
>
>Ballendo