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Non-stop extrusion for changing the feedrate

Posted: 04 Jan 2020, 20:51
by diego.cuevas
I'm traying to 3d print with variable feedrate depending on the blacks or whites of a picture. That part of the gcode is not a problem. The question is:
Instead of providing a value for E (Flow) for each line of G1 code, can any of you figure out a way on the gcode to have a constant extrusion?
Like if the extrusion would be 'out of control'... constant, no matter the distance between points.
I'm not sure if I explain myself. Like a 0 or 1 or ON-OFF for the extruder independently of the gcode.
Any idea is very welcome.

Re: Non-stop extrusion for changing the feedrate

Posted: 06 Jan 2020, 10:15
by tgala
Hi @diego.cuevas,
The 3D printer considers the extruder just another axis. Lets say you want the printer to move from (0,0,0) to (1,2,3) while extruding 5 mm of filament, the G-Code would be something like:
G1 X0 Y0 Z0 E0
G1 X1 Y2 Z3 E5
You might be able to do what you want by writing some kind of script that calculates the distance between two points and then multiplies that distance by an extrusion rate and then modifies your input G-Code to accept this modifications.

You might not be aware of this, but if you import a black and white PNG picture to Cura, it can generate a 3D file height map (i.e.: a 3D representation of that PNG where darker shades represent lower heights and lighter shades represent "higher" hights). That might help what you're trying to achieve :)

Re: Non-stop extrusion for changing the feedrate

Posted: 07 Jan 2020, 15:58
by diego.cuevas
That is what I was expecting...I mean, not to be able to split the movement from the extrusion. Ok, I will try another way.
Thanks for the tip of the Cura. I didn't know it was so advanced. I do those lytophanies modelling it in Rhinoceros.
Thanks for replying!