From: Marshall Burns (
Date: Fri Dec 14 2001 - 19:47:42 EET

From: "Bibb, Richard (PDR)" <>
> The problem with trying to come up with a system that evaluates RP systems
> is that it is in danger of comparing apples and bananas and not apples and
> apples. I suggest that a practical way forward is to compare RP system
> capabilities to product development objectives rather than comparing all
> systems to each other.

    One of the exciting things about this whole field of technology is that
there are so many different ways to accomplish its objective (to make a
solid object from a digital description and raw materials). I believe the
issue proposed by Paul Finelt in his "Stone Soup" e-mail has an even greater
long-term importance than deciding which *machine* to buy or use today.
Future machines will incorporate a variety of processes and the software
will have the challenge of determining which *process* to apply to creating
any particular shape and structure found in the CAD data.

    Perhaps a step forward for working on this problem from where we are
today is to develop a database of technology capabilities in terms of a
multi-dimensional matrix of materials, material properties, resolution
(in-layer and z), accuracy, solid formation rate, results repeatability vs
need for experienced operator, etc., etc. There's a wonderful book by M. F.
Ashby called "Materials Selection in Mechanical Design" that gives dozens of
two dimensional selection grids on the basis of many pairs of
characteristics. A computerized, multi-dimensional version of this technique
could help a user zero in on a desired domain of capabilities and the
processes/machines capable of working in it.

Best regards,
Marshall Burns
President, Ennex Corporation
Los Angeles, USA, (310) 397-1314

For more information about the rp-ml, see

This archive was generated by hypermail 2.1.2 : Fri Jan 04 2002 - 09:58:18 EET