Re: rp definition

From: Advantage Prototype Systems (
Date: Mon Feb 05 2001 - 21:03:08 EET

Good one, Terry. I think the problem lies in the 'Gee Whizz' factor. When
the first grinding wheel was invented, it likely caused a bit of excitement.
(I'm speculating, here. I wasn't actually there at the time.) At that point
the grinding wheel would have properly been categorized as a 'Rapid
Prototyping device', if there were such a term, and inclination to
categorize. As this became a common tool, the 'Gee Whizz' wore off, and also
the categorical fit. Perhaps this discussion should have been completed back
when we were all too busy to talk about it, and it was less of a commodity
Tom Husting

----- Original Message -----
From: Terry T. Wohlers <>
To: RP-ML <>
Sent: Monday, February 05, 2001 12:16 PM
Subject: RE: rp definition


This is an interesting thread with good comments and suggestions. More
food for thought: Is a grinding wheel a part of the technology that many
of us refer to as RP? Of course it's not, although it's much faster than
shaping an object by hand with a file, so one could argue that it is. What
about an EDM machine or a CNC-controlled flame cutter? Laser machining?
These and many others are forms of fabrication that are faster, when used
correctly, than alternative methods. How would/should we communicate with
one another when we are referring to the group of technologies that include
SL, SLS, FDM, 3DP, etc.? Do we broaden its definition to the point where
it loses its meaning? No one wants that. One could attempt to change its
name, as you suggest, but ....... you think we have confusion now .......

Best regards,


Terry Wohlers
Wohlers Associates, Inc.
OakRidge Business Park
1511 River Oak Drive
Fort Collins, Colorado 80525 USA
Fax 970-225-2027

Message text written by "Jeff Katz"
>What's wrong with using CNC machining to do "Rapid Prototyping?" In some
cases, depending on material and finish level, CNC machining is actually
more "rapid" then RP. If the question is how do you rapidly produce parts
directly from 3D CAD data, CNC should logically be included in the
classification, otherwise it's an arbitrary distinction.

We lump CNC and EDM in with all the others in our Rapid Manufacturing
marketplace. If you really want to distinguish SLA, SLS, FDM, etc. from
CNC, you really need to change the name from Rapid Prototyping to Additive
Prototyping or even Fabbing. Right, Marshall?

Jeff Katz
773.477.7374 x203
Fast, Free, Secure

-----Original Message-----
From: []On Behalf
Of Terry T. Wohlers
Sent: Friday, February 02, 2001 9:46 AM
To: Elaine Hunt; RP-ML
Subject: rp definition

Message text written by Elaine Hunt
>The Rapid Prototyping Report in 1992 defined RP as

The Fabrication of a physical, three dimensional part of arbitrary shape
directly from a numerical description (typically a CAD model) by a quick,
highly automated and totally flexible process.

Does this definition define what you do with rapid prototyping? Should it
be expanded and if so how would you change it?<


I've been using the following to briefly define/describe RP:

Rapid prototyping (RP) is a relatively new class of technology used for
building physical models and prototype parts from 3D computer-aided design
(CAD) data. Unlike CNC machines tools, which are subtractive in nature, RP
systems join together liquid, powder and sheet materials to form complex
parts. Layer by layer, RP machines fabricate plastic, wood, ceramic, and
metal objects based on thin horizontal cross sections taken from a computer


Terry Wohlers
Wohlers Associates, Inc.
OakRidge Business Park
1511 River Oak Drive
Fort Collins, Colorado 80525 USA
Fax 970-225-2027<

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