3D Modelling Cookbook

Bitmap logo to vector form

1. autotrace -color-count 1 -output-format eps -output-file logo.eps logo.ppm
2. pstoedit -f "dxf:-polyaslines -mm" logo.eps logo.dxf

We use the intermediate postscript file because then pstoedit gives us some control over the DXF instructions that get generated. OpenSCAD seems to have incomplete DXF support and so we avoid feeding it unsupported DXF by using the pstoedit driver options.

Repairing mesh with bad properties

It is a necessary condition for printing that your mesh be manifold in a topological sense, but also, that it is realisable in 3 dimensions.

• Meshlab - has repair filters but I haven't worked out what to do here yet.
• Netfabb Basic - Alerts you with a big red triangle with exclamation mark inside it. With your part selected go Extras -> Repair. In the dialog box that appeared press 'Automatic Repair' then 'Default Repair'. Once the operation has completed you should see the statistics for edges, triangles and shell faults set to zero (press update to refresh). Remember to press 'Apply Repair' after to apply the pending changes.
• Slic3r - --repair Repair given STL files and save them as <name>_fixed.obj

Slicing complex objects on remote machines

slic3r.pl --load fine-cerberus.ini -o orbits-fine.gcode -j 8 --resolution 0.1 --scale 0.5 --print-center 0,0 orbits-smoothed-4.stl

It seems the GUI auto centres the mesh on the print bed, hence the --print-center to override the default of 100,100 mm for the Cerberus. I think the default is OK for the centre of Taz (?).

Setting resolution to 0.1mm avoids generating gcode that results in moves too small for the physical printer to cope with. Should speed up processing but not verified.