RE: [rp-ml] A lot of questions..

From: Marshall Burns (
Date: Mon Sep 12 2005 - 21:23:29 EEST




            Thank you for your interesting post, and I apologize for the
difficulty of colloquial terms for the international audience. I generally
pay a lot of attention to this and do my best to make the meaning of my
writing clear without knowledge of “Americanisms.”


            I am way overdue to compile the responses to my surveys on
terminology and open source, and I’ve been fairly quiet on the list until I
get those done. But I got such a chuckle from your question about
“whatchamacallits” that I just had to reply. The fact is, I actually checked
the spelling of this “word,” if it qualified to be called one, before using
it. And these days, the only place I check spelling is also available to
you. So if you type that term into
<> , you will find out that it means “something
whose name has been forgotten or is not known.”


            I’d like to address the more important technical questions in
your post, but that will take more effort and will have to wait a while.
Some others will probably beat me to it.


Best regards,

Marshall Burns <>






From: [] On Behalf
Of Guillermo Theus
Sent: Sunday, September 11, 2005 09:48
Subject: [rp-ml] A lot of questions..


Dear list

I´m an Argentine man (excuse my bad english) who the crisis push to search
other horizons, I´m living now at Málaga, Spain. I had in Buenos Aires a
little enterprise dedicated to medical equipment, now I´m working in
architectural servicies. I use Autocad both at 2D and 3D to translate
architectural planes into files for laser cutting or STL to build scale

Please let me say a little word especially to the friends from USA : think
at everyone who need to deal with english!! In this list I see people from a
lot of countries: India, Turkey, Brazil, Uruguay, and so on, please think
that you often use a lot of colloquial words we never found in a dictionary,
e.g. what means “watchacamallitis”?? Perhaps if sometimes appear between
brackets a little explanation on such words... Even so, let me vote on

RP shows still working (look at these list name), perhaps it became

3D printing I feel is a term that quickly approachs this tech to people that
is not in manufacturers field (think at people you meet that ignores yet
wath is CNC milling), it describes well the desktop, cheaper machines.

Additive manufacturing. I vote for it looking ahead, it likes a more
comprehensive description of these processes.

More than eleven years ago I feel interested in the posibilities of RP
technologies, we made then a little piece in a SLA machine. I´m an “amateur”
in this field, now I´m working in architectural scale modelling, making
several projects through service bureaus in different technologies. It´s a
hobby for me think at better and cheaper methods on 3D printing, for this I
want to make to the list a few questions:

I read some about studies on the use of a photopolimer film, instead to be
cut by a knife or a laser, exposed trough a lcd screen that project the
corresponding shape onto the last layer. An other approach could be the
projection of the layer shape trough a lcd cannon, always thinking in avoid
the XY scan over the film. Perhaps this method has the trouble of the light
dispersion on borders, and the precise control of the depth of

Does somebody knows if exists a photopolimer that meets these requirements?
It should be inexpensive and easily to remove in a solvent, thinking always
in a stack of sheets to avoid support structures, then we need to remove
easily the waste material.

Another idea: if we have a polimer film that needs a little of catalyzer to
activate polimerization (or photo activated pol.), we could use a kind of
photocopier cylinder to spread a black powder (like a toner) that contents
the catalyzer. If exists a powder than itself polimerizate the exact shape
of the layer, wonderful! Then we don´t need light..

If we need light (UV or visible), a black catalyzer powder spread over a
transparent film would help to avoid the polimerization through previous
layers, moreover than we only need an illumination over the whole layer,
instead a XY scan over the layer´s shape. Excuse me if I don´t know well the
state of the art, take this words like a friendly chat with an ignorant guy.

Best regards

Guillermo Theus

Málaga - España


This archive was generated by hypermail 2.1.7 : Mon Jan 02 2006 - 08:09:20 EET