Another Roland drag knife mount

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This topic contains 6 replies, has 4 voices, and was last updated by  Mark 7 months, 1 week ago.

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  • #86326

    Alexander Pruss
    Participant

    I adapted the Roland-style drag knife holder mount that I had made for my 3D printer to work with the MPCNC. It has a plastic spring (ABS recommended, unless you want more tension) for pushing on the tension button at the top of the holder. I haven’t tested it yet with the MPCNC. Back when I used it with my 3D printer, I drove it with my [gcodeplot](https://github.com/arpruss/gcodeplot/) python script, which I’ve adapted to work with MPCNC.

    https://www.thingiverse.com/thing:3388793

    dragknife

    #86333

    Ryan
    Keymaster

    That looks pretty good, if you spring mount the body instead of the blade you can use the body to limit depth (for things like cutting vinyl and not cutting the backing) and the spring to control overall tension for different materials.

    #86335

    Alexander Pruss
    Participant

    Good point. I should experiment more.

    #86343

    Jeffeb3
    Participant

    That software looks pretty cool. Do you have some images you can share of what it’s capable of?

    #86351

    Alexander Pruss
    Participant

    There are some pictures here: https://www.instructables.com/id/Use-3D-Printer-As-a-Plottercutter/

    1 user thanked author for this post.
    #87352

    Alexander Pruss
    Participant

    If you’re interested in using the software, on my github I included two sample mpcnc configuration presets: mpcnc-10-10 and mpcnc-5-10-overcut1.

    python gcodeplot.py -c mpcnc-10-10 filename.svg > filename.gcode

    is for drawing. It generates gcode that assumes that the pen starts in the lower-left corner of the page, 10mm above the drawing position. (I prefer that to starting with the pen right on the page, so it doesn’t need to make a mark. One strategy I’ve used is to put some aluminum foil on the page, adjust the z position on top of the foil for good tension, lift 10mm in Repetier Host, remove foil, print.) It cross-hatches shaded areas by default. Cross-hatching density corresponds to how dark the color of the polygon is, and can be adjusted in the code. (I haven’t tried it, but one could presumably calibrate the density so that a marker shades blacks completely.)

    Coordinates are reset by the gcode to be 0,0,10 at the starting position.

    For cutting:

    python gcodeplot.py -c mpcnc-5-10-overcut1 filename.svg > filename.gcode

    This preset assumes the cutter starts in the lower-left corner of the page, 10mm above the cutting position, and turns off cross-hatching (!).

    Any text in the svg files needs to be converted to outlines in Inkscape. Also, if there are any overlapping polygon in the svg, hidden features in the lower polygon will also be drawn. (To get rid of overlapping polygons, you can use this version of the path ops extension in Inkscape with the Trim option: https://github.com/quintesse/inkscape-extension-pathops )

    I still need to learn how to use Estlcam. I find its UI intimidating.

    #89067

    Mark
    Participant

    This is the one I want, for both a pen and the drag knife: https://youtu.be/HciNR-tskwQ

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