Sintering and Stereo Litography

As a technological concept, SLA printing (Stereo Lithography Apparatus) and SLS printing (Selective Laser Sintering) are superior to FDM printing (Fused Deposition Modelling): the object is supported by the resin (in SLA printing) or the powder (in SLS printing) during the printing process. There is no need for a scaffolding construction on overhanging parts.

Both concepts use curing the printing material, rather than melting it, so heat plays a smaller part. The objects won't warp as much due to cooling down.

On the downside: both printing concepts are more expensive (especially SLS), and tend to get pretty messy, with resin and powder dust all over the place. In an educational environment (especially in the over regulated environment of the Netherlands), that can be an issue.

This project has quite limited experience with SLA printing (Stereo Lithography Apparatus) - the machines are now printing for some 6 months, but the first results are 'promising' as one would put it.

As for the SINTRATEC SLS (Selective Laser Sintering) printer, a Swiss Indiegogo startup project, that one arrived a week ago, as four big boxes filled with all kind of metal parts and screws and electronics and cables… It's an IKEA project on steroids, with a 500 pages construction manual.

We'll keep you posted on the building of this thing (good luck, Eric Steenman…)…

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Printing Eifel towers

It seems almost all FDM (Fused Deposition Modelling) printers are very good at printing their 'logo-model'. These are as a rule, small, symmetrical objects. And that's no accident: due to the thermodynamic limitations of the printer's concept, non symmetrical object warp out of shape quite quickly, while printing. Only at very low printing speeds, more complex non-symmetrical objects can be achieved. To sum it up: the Eiffel tower is the wet dream of any 3D printer: perfectly symmetrical, designed to counteract all warping stress within the model.

That's pretty visible when one watches the '3D printing Star objects': as a rule, these are perfectly symmetrical objects (Martin Zampach's vases and lamp shades are a nice example):
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This has to do with FDM technology: similar to a hot glue gun, the print head is layering heated plastic. These layers shrink while cooling down, causing the object to warp out of shape, especially when it's not symmetrical.
In order to print quicker, these layers have to cool down almost instantly before a new layer is applied. If not, the next layer will smear into the previous one, resulting in a pastic blurb.This cooling process - with some ventilators attached to the printing head - is very difficult to manage: it depends on the shape itself, room temperature, the plastics used and even the color (black radiates heat quicker than white).
Warping can cause the object to detach itself from the base, resulting in 'spaghetti in outer space'…

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Calibrating the FDM printer as such is a very haphazard process, which has to be redone for almost each different object, each material, each color, each room temperature… At least, it teaches students (and teachers alike) to work in a very methodical organised way. Logging all the settings and their results, is crucial.

That's the inevitable thermodynamic paradox of FDM 3D printing: plastic should cool down from some 200°C to room temperature instantly, which of course, it doesn't. Especially in larger objects, where heat accumulates during the printing process, it will ruin the print. The only solution is slowing down the proces to an excruciating slow pace: printing overnight to produce one, small object is the rule, not the exception.

Will FDM printing revolutionise 3D prototyping? Definitely not, in spite of the popular press. But it will become a fascinating designing tool, with it's own weird limitations and rules. It can produce some marvellous object, but the machine (and technology) itself dictates to a large extend the rules of the designing game. Well, that's not so different from fresco-painting, after all…

Peter Missotten nov. 2016

Student reports

We asked students to document their experiments in 3D printing. In return, the professorship TDA pays for the printing material, creating a classic win-win situation.
That gives quite an about of interesting reports on all kind of experiments in 3D printing.
We post them on this site, here.

...that all printers are created equal...

After printing over a year now with 3 very different (both in specs and cost) FDM printers, it turned out all of these printers have their quirks. Print quality and reliability is not hugely different. Even the cheap Wanhao Duplicator's prove to be of quite good quality (at least, 3 out of 4) and print quite decently, in so far as a FDM printer will ever be able to print decently.
The Ultimakers are the most popular ones, due to the very user friendly software and their reliability. But costing almost twice as much as a Wanhao (which is a double head printer), they should…

It is pretty amazing how slow this over-hyped 3D printers marked evolves: it took Ultimaker 'ages' to come out with a double head printer. This double head is pretty crucial for complex designs, where you need to print a 'scaffolding' for overhanging parts of the object. One head prints a soluble scaffolding, the other head prints the object itself.

In the next years, we want to reflect with students and teachers alike on their symbiotic relationship with this new technology. How do they manipulate the technology and how does the technology manipulate them? How to deal with this symbiosis - how to describe and how to master it. In short: how to lead the dance…