RepRap Mendel
How To Use the 3D Printer
1. Get a 3D Model (.stl file)
You can download an STL file, scan an object using a 3D scanner, or create one using a 3D modelling program.
Places to download 3D models from:
- http://www.thingiverse.com/ (recommended)
- http://www.georgehart.com/
- http://www.cs.duke.edu/~edels/Tubes/
- http://sketchup.google.com/3dwarehouse/
Ask Ben about his 3D scanner.
3D model editors:
- Google Sketchup 8 (available on 3D printing workstation)
- Blender
Sketchup doesn't support STL file format natively. You have to use "Import" and "Export". On Import, it's important to hit the Options button and set the units appropriately.
2. Convert the STL file to GCODE
A GCODE file contains opcodes that directly controls the behaviour of the 3D printer at a low level. The conversion from STL to GCODE is non-trivial, and there's a lot of fiddling you can do during the conversion that will make the difference between a good quality printout and a mess.
There are a number of different packages available for generating GCODE:
- Whatever package Kevin has been using. He has documented a number of problems and limitations in his blog post. http://www.kwartzlab.ca/2011/08/reprap-mendel-3d-printer-working-now/
- Skeinforge seems popular and well supported, and has lots of knobs for tweaking the conversion. Doug is planning to focus on mastering this program.
- Alex W mentioned some others: Pronterface, Sprinter SW
You specify the material when you generate GCODE. We currently have ABS. PLA is the other popular material, which we can mail order if there is interest.
- PLA is claimed to warp less during printing, and smell better (fumes less toxic). The printing temperature is lower. It's biodegradable. It's more brittle, and very hot water will melt it.
- ABS (what we have) is stronger, less brittle, more durable, has a higher melting point.
You specify the temperature when generating GCODE. Kevin has had success printing at 220 degrees (ABS).
- Lower temperatures are preferred for: small printed areas, large overhangs, or other situations where faster phase change is beneficial lower temperatures are preferred. Lower temperatures also reduce swell inside the extruder and decrease the extrusion after feedstock drive is stopped.
- Higher temperatures allow the build material to flow into printed areas and extrude faster, and bond to previously extruded stock faster. At the same the filament becomes more viscous and more plastic evacuates the extruder after drive is stopped. A fan can help the plastic solidify faster and improve performance.
Lots more parameters to tweak.
Skeinforge docs: http://fabmetheus.crsndoo.com/wiki/index.php/Skeinforge
