Well… At first I wanted to mill an extruder from aluminum, use proper gears and so on. I still want to do that. Sometime…But time is precious and starting with stuff which actually works makes things easier. When it is working fine you can start to meddle with certain parts being sure to have your sources of error limited.
Anyways, I ended up buying an extruder at the reprap fab. It’s a Wades Extruder modified by a guy called Greg and it’s got a custom build hot end produced by the reprap fab. It comes ready to run, just add a stepper motor, 4 m3 bolds + washers, an adapter to fit it in a 43mm chuck and some cable.
I used Qcad to make a simple Adapter Design and milled it from 5mm MDF (Middle Density Fibre Board). It’s cheap, sold virtually everywhere and easy to machine. The .dxf file can be downloaded from thingiverse.
The Assembly is pretty straight forward: Use woodscrews and the predrilled holes to bolt it together. Grind away any part of the screws which would collide with the chuck. The picture above shows a slightly outdated ver sion, the “hole” for the cables has been changed:
Assembled on the mill:
The bracket holding the connectors is also on thingiverse: http://www.thingiverse.com/derivative:21032
Attaching it with magnets makes it pretty easy to put it aside when using the spindle: