Wednesday, May 15, 2013

Fab Academy: Machine and Mechanical Design

For our team machine design project we are building a Fabscan 3D scanner for the new Strathclyde University Fablab. I have taken on the task of adapting (very lightly) the files for 3D printing (a laser holder and turntable component) and printing them. These are Openscad files, available here . I found an alternative turntable component on Thingiverse here, that looked better in design so decided to use this as a basis. Having not used Opencsad much, it took a wee while to decode what bits of the script did what. Thankfully a lot of it is commented both in English and German. The radii for holes are in particular easy to find at the top of the script as constants as in this example from the laser holder file:

lhIR = 6; //this is where you define the radius of your laser module!
lhOR = lhIR+6; 
lhH = 8;

shIR = 2.5;
shXS = shIR+2*lhH;
shYS = 2*lhOR;
shZS = 15;

nutY = 2.6;
nutZ = 5.6;

I did have to edit the radius of the laser module to match the one that we ordered here.

Having edited other holes to match our stepper motors, I was ready to print. This was fairly straighforward, being quite experienced with out Ultimaker. I did encounter a wee extrusion problem caused by our filament being tangled on the reel - required me to cut it free, untangle and reload the filament. The trick to this is to keep the nozzle temperature at melting point (228 degrees for our PLA) and manually run the extruder to make sure it is properly gripped.

Having printed the parts, I found that the holes for the stepper motor spindles in particular were a good mm too small, so redrilled them. I would recommend doing this in any case to ensure they are completely circular. This was less necessary for the larger laser module hole.

The parts are ready to be assembled into the machine - more soon!

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