Friday, September 14, 2012


Colour Mix Progress

Pia Taubert, who has been working for the past few months in the RepRap Lab at Bath on the colour mixing project, has got continuous control of the mix working.  See the video above.

The proportion of the mix is specified in the G-Codes.  So we have a cheap and cheerful way to experiment: read in a G Code file for a conventional monochrome object, then replace the E fields with a mix proportion and write it back out again.  Make that mix proportion a function of the X, Y and Z G-Code values.

That isn't a sensible way to do things properly, but it does allow a lot of experiments to be done quickly because the function can be anything that can be put in the program: linear change, sine waves, cliff edges etc. etc.

Superb progress, the gradients are lovely. having gcode controll over gradients is a big step.
For this to be truely usefull for easy creation of grayscale (or bluescale in this case) there is more to research. (from back to front)A transition from stl to something that supports colour information. Slicers to process the files. (open source) cad programs to create the files.

Interesting developments ahead, I feel incapable to help but nontheless looking forward to the little steps.

Good luck on the road ahead!
@bitflusher: the AMF format (Additive Manufacturing File format) supports color specification: .

I believe (but could be wrong) that Slic3r also supports this format - although I guess it probably doesn't generate gcode for color transitions at present.
The color mix needs to be generated as a percentage of F with each filament added using A% B% C% D% E% =100% and extruding their individual volume of F(as a example of CYM+BW) and should be derivable from computer color definitions to a certain extent.

The gradients are very nice! But is it capable of doing sudden shifts for something like a checkered pattern? Has anybody experimented with this?
I was explaining your process to a friend the other night and he came up with an intriguing alternative, why not use only natural filament and inject the dye into the extruder? The mixing issue is the same, ensuring the dye and plastic is fully mixed, but the colour density of the dyes should be consistent. I did a little research but couldn't find much one dye supplier and the EU standard

European OGD’s dyes are regularly tested and based on the analytical results they meet the following regulations.

Europe Resolution AP 89-1
Europe EU Standard EN 71

Has any one considered this method already?
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