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

From: Markus Hitter (
Date: Tue Sep 13 2005 - 11:59:26 EEST

Am 12.09.2005 um 17:08 schrieb

> I read some about studies

Are these available in the Internet? I'd be keen on reading them.

> on the use of a photopolimer film, instead to be
> cut by a knife or a laser,

One drawback of such an technology would be the enormous amount of
waste you'd produce. This doesn't hurt so much when you have to
dispose (almost) ordinary paper (LOM process), but if you have to get
rid of complex/hazardous chemicals, possibly even solved in some
fluid, it'll become an issue.

> exposed trough a lcd screen that project the corresponding shape
> onto the last layer.

I've heard about the usage of LCD screens a few years back as well.
At the time then, they seemed to have not enough contrast and not
enough resolution. LCD technology improved a lot since then, however.

> 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 donīt 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 layerīs shape.

Yes, great idea. I even know about a machine which intends to deploy
such black powder layers. Surely, there are challenges at the detail

  - You can modify a photocopier or laser printer. Such devices have
a lot of traps built in to make your life hard. Think about page
counters built into toner cartridges to make sure the user is forced
to replace the cartridge every 2000 prints. Think about all those
detectors built in to detect paper jams.

  - You could built such a device from scratch. Make sure you have a
friend with an excellent understanding of how to design high speed

  - Powder layers deployed by photocopiers aren't of even thickness
at all. If you want to use the powder as build material, you want
some precision milling capability as well.

  - If you want to use the powder as a light mask only, you have to
recycle the mask after each layer or you have the disposal problem
yet again.

  - If you want to use the powder as a catalyst only, you'll have to
remove it before building the next layer or to make sure it won't
continue to catalyze after some time. It could catalyze all your
build envelope after a longer time. If you need larger amounts of
catalysts, material strength can suffer.

  - Exposuring a laser beam to the photopolymer directly seems to be
much simpler. Requires an expensive high-power laser with a relative
thick beam diameter, though.

> For a new
> technology to be successful, it will have to solve some of the
> fundamental problems of
> RP today; for example: speed, accuracy, size or cost. Look at your
> solutions
> in terms of solving one or more of those problems.

That's easily said. You probably have to have a lot of money in your
back to compete against companies like 3D Systems, Z-Corp. or Objet
Technologies. Developing technical applications in an hobbyist
environment isn't as cheap as developing and testing e.g. Internet
search software (Google). You'll have to do quite an investment
before you have a first working "sample" of a machine you can show to
your fund raisers.

> Excuse me if I donīt know well the state of the
> art, take this words like a friendly chat with an ignorant guy.

Another way would be to keep a more amateurish status and join
projects like RepRap <>.
They seem to have good backing of a university (helpful for patent
research, getting some public research funding, having a central
"place") and are obviously very open to new ideas.


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Dipl. Ing. Markus Hitter

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