ViScan 2D camera

[[Pa...]]

Anyone have any experience with the Zeiss Viscan camera used as XXT stylus on a Contura or Accura?
Software edge routines work well? Accuracy? Etc.
Most importantly, does it correlate to hard probe data from a part? (i.e. can some true positions in a program be touch probed while others are measured with the camera and the measurements "sync up"). I understand this is the way it is supposed to work, but I tried a couple years back and could not get good correlation.
thank you.
PaulS

[[No...]]

I don't know about the camera you mention, but on an O-Inspect it's no problem to switch between stylus and camera within the same program. You can even change the strategy of optical features to tactile and vice versa (or define an alternative optical/tactile strategy for both). But this doesn't mean you'll have the same amount of measurement uncertainty. Optical measurements are very different from tactile probing and generally less accurate (but don't ask a number). They depend on a lot of factors, proper lighting being only one of many (but the most important). The edge routines are simple and work well if the lighting situation is good. Light from below is the best option if it suits the measurement, as you have a well defined bright/dark transition. With light from above it all depends on whether you're able to create enough shadow at the right spot. Surface texture can have a great influence on the result. Depending on your parts you may often meet a situation where 10 people around the machine could immediately identify an edge on the screen with their eyes, but the machine won't find it because there's not enough contrast.

[[Pa...]]

Norbert, very good. Thank you.

[[Al...]]

We use a Viscan on our Contura G2 with RDS. The only stylus we qualify is #1 (-Z). We don't use it for tight tolerances because qualifying with a 8mm ball is not that accurate. That is also why we only use the one position; 2-5 are not easy and less accurate.

If using the #1 stylus only, you would need to use the tactile/optic program that is used on the O-Inspect to get accurate readings. This means getting a light table and the 16mm ring gage. On our O-Inspect, I get no more than a 2 micron deviation in X and Y values at all magnifications using the offset program.

[[Pa...]]

Alan,
Thank you for the info. I see Viscan sell on EBAY now and again for semi-reasonable prices. I was thinking of using for true positions of .75mm thru holes with .1mm tolerance.

[[To...]]

You need to look into whether or not your machine is configured to accept the ViScan. In other words, it may not be wired for it.

[[Pa...]]

Ahh, a possible catch. Thank you Tom.

[[Al...]]

And you will need the proper frame grabber card ($4K+) and other associated computer hardware. If buying from eBay you need to know how old it is to get all the right stuff to get it to work.

A Position value of 0.1mm diameter is pretty tight for a low power optical sensor, in my opinion.