Prusa i3 MK2 as a plotter by maxstrauch

Last crawled date: 3 years, 1 month ago

I wanted to label a CD and had only my Prusa i3 MK2 3D printer on hand. Since I didn't wanted to create a permanent installation I designed this part to simply slip over the extruder stepper motor. As it turned out I did not need a screw at all to clamp the holder to the stepper motor - it works fine only by friction. The pen is held in place by some holders which I hot glued on.
It uses two rubber bands to hold the pen. This works better than I expected since the rubber band gives enough flex (in z direction) so that the pen can move slightly up and down so that it is not pressed hard against the plotting surface and therefore damages nothing.
This was the first 3D part I designed and printed. Therefore it is not ultra high quality and contains some flaws like the unnecessary screw terminal. If a screw presses the semi-halfs together the whole part warps and is then crooked.
See it in action: https://www.youtube.com/watch?v=YQdHdr4Irz8
Workflow to plot something:
To plot something I created an SVG file with the image to plot (in the case of the video the outline of the DVD with the text) and then used http://www.makercam.com/ to generate the G-code. I then open the G-code file and
add the G28 X Y command (G28: Move to Origin (Home), see http://reprap.org/wiki/G-code)
remove any T and M commands (e.g. T0 M6 and M3) in the file
See the following example file (unmodified):
(Generated by PartKam Version 0.05)
G21 G90 G40
(profile 1)
G0 Z15
T0 M6
G17
M3
G0 X40 Y22
G1 Z-1.5 F800
G3 X42 Y24 I-11 J11 F1500
And now modified:
(Generated by PartKam Version 0.05)
G28 X Y
G21 G90 G40
(profile 1)
G0 Z15
G17
G0 X40 Y22
G1 Z-1.5 F800
G3 X42 Y24 I-11 J11 F1500
You really need to experiment a moment to get everything right and also consider the z movement to "activate" the pen. I do this directly in Makercam and usually use a save height of 5 mm and no plunge depth at all.
Another tip: if you use the Makercam G-Code straight on the 3D printer I got many errors and figured out that the numbers (a line usually looks like "G3 X44.24111675126903 Y39.01015228426396 I-13.98984771573604 J-2.6675126903553297") are too long. So I wrote a little cleanup PHP script (cleanup-script.php) which rounds the numbers to less decimals (the line looks afterwards: "G3 X87.8122 Y95.9645 I46.0305 J46.0305"). This works fine.
I use the latest Prusa i3 MK 2 firmware on my printer, the 3.0.9 version. And I use Pronterface to stream the G-code to the printer (connected via USB).