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In article <2826@pur-phy> piner@pur-phy (Richard Piner) writes:
>
>A couple of days ago I got a call from a chap down in Indy who
>has an interesting problem. He needs to measure the shape of
>a molding in three dimension to within 0.025". And he needs to
>do it fast. What they want to do is take a molding of a piece of
>human bone and machine an implant from the molding. He says
>that the CNC milling machine can do the cutting in under an
>hour. The problem is getting the digital information to program
>the mill.

Quite true.  Back when I worked at Computervision (now owned by
Prime), writing Numerical Control Postprocessors, one of our customers
was doing exactly that for replacement knee joints.  They were
matching the replacement part to the existing bone-end for a more
comfortable fit.

>So, does anyone know of a commercial system that can measure
>the shape of an object in three dimensions and do it quickly.
>Most machine vision systems are not fast enough or accurate
>enough. Anyone know of a 3d profileometer system that is up to
>this task?

Sure, they're called "Coordinate Measuring Machines" (CMM's).  Like NC
machines, you program them to move around your part.  Instead of a
tool, however, the head ends in a ball-end probe of a known accurate
radius.  When the probe touches the part, the current coordinate of
the machine can be stored.  Like NC machine tools, they're very
expensive, very heavy, and very accurate.


Copyright 1989 Greg Wageman	DOMAIN: greg@sj.ate.slb.com
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