Just thought I'd share a video of my Roland 3D Digitizer.
I have had it for a while now and have produced some nice scans with it. The way it works is that it's got a fine needle connected to a Pizeo Transducer. When scanning, the Pizeo emit's a high pitch ringing that makes the needle vibrate like a tuning fork. If the needle touches something, the ringing is absorbed by the object touched, and the ringing stops. A sensor listening to the ringing detect's this change and stops the machine from moving in all 3 axis. The scanner then records this position in X Y and Z.
It then retreats and mooves accross buy the scan pitch distance and then continue's to scan the next point.
"http://www.youtube.com/watch?v=SqcLJ05qsls"]YouTube - Roland Pix-3 3D Touch Probe Digitizer
Here you can see the PIX-3 scanning a small plastic frog. The video is just showing a demo of how it works and then it shows the outcome of a full scan I did of the frog some time ago. The frog was scanned at 0.05mm scan pitch. If you look closely you will see and error that is created when scanning a hard surface. It appear's as a small ridge allong the side of the frog. The needle sometimes vibrates off to the side when it comes into contact with a hard part that is just the "wrong" angle. For instance the needle is touching the part at such an angle that it bounces off and the probe initally doesn't detect the touch because the needle is still ringing. In this case the probe continues on it's way down in Z untill it touches in a way that is more direct and the ringing stops. As soon as the probe stops ringing the digitizer stops and records it's position which in this case is incorrect. The frog is very small and the error line is extreemly small.
Besides this it works perfect.
Last edited by chich2; 09-05-2008 at 07:15 AM.