RE: 3D printing

From: Karl R. Denton (
Date: Mon Jul 14 1997 - 14:59:12 EEST


YES to all of the items that you mention, however...the models that have been produced on the concpt moderel were either so small it gave no indication of hor the part would acutally be or the model(s) would build bad and start delaminating on completion. We use one of our "real" rp machines to produce full scale verifaction models that IF prove to be correct will be investment cast. There is no possible way that this can be done with the "concept" modeler.

Your last comment "The most important is that these models must be ready within say a coffee break" NOT onece did the concept modeler finish a part by the time we had a coffee break! In fact it, even the designers that have used the equipment have complained about the length of time it taks to build even a small model! You seem to forget some of my previous comments: The designers (the guys and gals that you clame need such a device) have stopped using this equipment on their own. Thay have four that it is more usefull to wait untill they get a design close enough and have us build a full size model to review. One of the problems being that the modeler was so rough that it would drop features smaller then a given size, not good.


From: Delft Spline Systems[]
Sent: Monday, July 14, 1997 8:01 AM
To: Karl R. Denton
Subject: RE: 3D printing

Karl Denton wrote
>I have always made the statement that a "concept modeler" is a useless
machine. And that seems to be the case with ours. I can not understand why
RP manufacturers think that companies should want to buy a machine that lets
designers (the guys/gals that get paid to design and presumably to "see"
the 3D of their design on the screen) pop out desk ornaments all day. The
concept modeler that we have and the new machine cost nearly the same. One
produces parts that good for setting next to the coffee cup and the other
produces parts good for highly detailed investment castings.

I cannot resist to comment on this.

Karl, it is obvious that you are not the guy that gets paid to design and
see 3D one the screen.

Have you ever:
- tried to see and imagine the actual 3D situation for a real complex
CAD design you were working on
- tried to discuss this with a college, pointing with your finger on
the screen (creating the well known dirty spots)
- tried to evaluate the quality (smoothness) of a freeform surface using
graphical tools only
- tried to imagine how a new say shaver would feel in your hand
when looking to a rendering only
- tried to present 5 different concept designs to the management
using renderings only
- idem to marketing, idem to a user panel
- do imagine the pre-cad situation, where each designer uses a
drawing board. The other designers can see what he/she is doing
and discussions will start that enhance the quality of the design.
Now the current cad situation. Each designer is seated in front of
a monitor, zoomed in at some minor detail. Nor the colleages nor
the chef can see what he is doing, so the discussions will not
start. Finally do imagine the difference of one or more concept
models located at every desk.

All these activities are needed in an early stage of the design
process (read any design handbook). The most important is that
these models must be ready within say a coffee break. The
concept modeller must thus be directly available: being used only
20 % of the time is OK: when this would be over 50 you need a
second machine. Do imagine the percentage for your desktop
printer or copier.

The key point of course is the price: This can only be true in case
a concept modeller is as cheap as a 2D printer or copier. Current
systems like the Actua are still far too expensive (at least a factor 10).

Finally (sorry, cannot resist this one too) take a look at the lowcost
Modela concept modeller to be used for styling block models in foam.
It uses CNC milling technique and can be found at
This one is sufficiently low priced (less than your color monitor).


Lex Lennings.

Delft Spline Systems, The Netherlands.
Active in CAD/CAM, Rapid Prototyping and NC milling
Email :
Web :

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