jeudi 12 août 2010


-> The aim of our project is to provide to the researchers a rapid prototyper which uses the Stereolithography(SL) technology.


In our case, we don't use a laser to trace each layers of the volume, we use a projector which project white patterns on a black background (second image above). That's why we will be able to print volume with a precision close to 1µm.
The SL process needs a photo-sensitive resin. The one we use is described here. We're still looking for new chemical formulas about this kind of resin. If you know one, this could be really helpfull for us, so don't hesitate if you want to post a comment.



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STL Chopper


STL Chopper is a software which has been created for the project. It allows to view, manipulate and slice STL files.
STL Chopper is always composed by two windows at least. The first one called "Visualisation" shows the STL file which has just been opened. You can manipulate the 3D object thanks to your mouse and you can move it by using ZQSD (on AZERTY keyboards). The up and down arrows settle the zoom and the left and right arrows move the cutting plane in the volume. Here is an important point. This cutting plane represent the position on the Z axis of the layer showed in the second window called "Impression" ( = Printing ). In this window too, you can move the drawing by using ZQSD and settle the zoom with up and down arrows. Moreover you can change the lines weights with O and L keys and you're able to change the gray level of the drawing using the mouse wheel when the visualization window is focused.
Actually, "Impression" is the window that should be projected on the resin during a printing. The liquid will become solid under the white pattern and thus you can reconstruct the whole volume by moving the layer. There is a short video demonstration of STL Chopper below.


If you press P, a parameter window will pop up. This window will ask you some values. The first and second fields may be filled and we advice to not change these values. In the third field you can set the number of layers that you want to cut the volume. Then you'll can choose how long each layer has to be projected on the resin. The two following fields are used to set how long should be the rest step (If you want X sec of rest, put X/2 in the these two fields). And to finish, the last field is the real volume's height in millimeters.



All those parameters are usefull for the printing. Thanks to them, STL Chopper can print any volume automaticaly. Moreover, STL can provide png images of each layers of the volume.



STL Chopper has been written with the Processing language based on Java, and that's why a JVM is needed. The 3D rendering requires an OpenGL compatible video card. unlekkerlib is used for the STL import. The source code is available here.
Creative Commons Licence STL Chopper by Quentin Perret is licensed under a Creative Commons Attribution 3.0 Unported License.

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We move the structure which is being print on the Z axis thanks to a step-by-step motor and a long screw. We tied a flat to the screw with a nut. This flat can only move along the Z axis. Therefore, the motor+screw rotation moves the plate. The engine is piloted by an Arduino card. The source code is available here.
Creative Commons Licence Step Arduino Code by Mathieu Savy is licensed under a Creative Commons Attribution 3.0 Unported License.