Texture mapping with feltpen carousel?



  • Hi guys,
    it's only a wild idea yet, but I need a reason to keep me from doing it. So please talk me out of it!
    The plan is to do texture mapping with felt pens dyeing the filament. The idea to add color by using feltpens isn't new, but I haven't heard of someone who actually tried to map an image to the outer perimeters or upper layer.

    The mechanical part consists of a pen-carousel with several pens of different color surrounding the filament above the extruder. Each pen has a solenoid to move it away from the filament.
    Defining different tools, it should even be possible to mix those pen colors.
    The whole arrangement rotates slowly around the filament, hence pen carousel. The rotation allows each pen to dye the whole circumfence.

    Now the firmware or post-processing part.
    Controlling the pens activity requires a lot of brain. The preprocessor needs to know the filament length between nozzle and the pen-carousel. (easy try and error)
    It also needs to know where in the gcode it can find the outer perimeters or the top layer.
    This can be done by defining a certain speed in the slicer exclusively for the tracks we want to dye. A postprocessor should be able to search for a line that contains G1 X...Y... F3456. (where F3456 is the exclusive speed that marks the surface)
    Now it has to calculate where in the gcode it has to insert the pen-tool directives to compensate the huge? nozzle-carousel distance. It sums up all the E-related lenght's that occure before the track in question. Retractions with G11 are no problem as long as the postprocessor knows the retraction lenght.
    Also the printspeed of the code, where the tool- directives are to be placed,is important.
    The pen-tools have to be in sync with the momentary filament speed and also be aware of retraction moves.

    I might have forgotten a few details, but this is the idea in general. I hope my lack of english tech-talk didn't confuse you too much and you got a picture of what I try to achieve and how.


  • Moderator

    I support your desire to try this. Sounds cool.


  • administrators

    @o_lampe said in Texture mapping with feltpen carousel?:

    This can be done by defining a certain speed in the slicer exclusively for the tracks we want to dye. A postprocessor should be able to search for a line that contains G1 X...Y... F3456. (where F3456 is the exclusive speed that marks the surface)

    This may work, except that is valid to send, e.g.

    G1 F3456
    G1 X100 Y100 E0.1
    G1 X101 Y101 E0.1
    G1 F2345

    etc

    So it would need to collect all lines until the feedrate changes. Better if you can, to get the slicer to make all lines as "outer permeter" or "top layer" with a comment.

    when i experimented with manually colouring filament with pens many years ago I found that, like with mixing nozzles, the transitions were not sharp. you ended up with a fade of pastel blue to pastel pink etc. YMMV with different pens and different plastics (that was with sharpies and natural ABS AFAIR).

    Before going to the trouble of making the hardware or coding the post processor I would try and see what the sharpest transitions you can get. I suppose you can add a purge area (and purge in infil as well)..



  • Thanks for the encouraging comments and handson experiences.
    @Phaedrux Is it the right subforum?

    I figured, it would be easiest to ink the filament in a separate process. The filament speed would be steady without retractions and such...
    Also it seems best to let the carousel turn 360 CW and 360 CCW. Wiring the solenoids is much easier then.

    Before I woke up my printer from it's 3 years beautysleep I've built a pen plotter from scratch. I made a short video, how the solenoid (12V car relais) and felt pen worked together.
    Maybe it's easier to dye the printed part with a multi-pen plotter. At least for flat top layer texture mappings....



  • Today I tried to get the latest news about THE post processing app for RRF3 and eg. PrusaSlicer. But informations were sparse.
    The manual of PS mentions a way to implement scripts and guided me to a github page with 4-9 years old examples. 😲
    I'm sure there has been a development going on in the last few years, especially with the SBC-option for Duet3.

    So what's your favourite post processing app on a Raspberry?
    It should have features like finding a string, replace and insert command lines, extract numbers and convert them from string2float.


  • Moderator

    I think there is more discussion of prusaslicer post processing on the prusa forums. I don't do much post processing myself but I do recall finding myself there at one point.



  • I tested 4 different felt pens from different brands with white PLA and 3 of them hardly stick to the filament or dry over time.
    Only a noname permanent marker did the job and I could extrude some colored filament in free air.
    The result was quite disappointing, I could hardly see a difference. Black turns into shades of grey 😉 and red gets pink.
    A mix of red and blue finally showed pale violet. I believe it was better because I used twice the ink.
    I also noticed that a lot of the color sticked to the nozzle and my hope is that the colors show more clearly when the nozzle actually prints something.
    I will build a carousel now for the pens I chose and see where a thick layer of ink leads to.


  • Moderator



  • @Phaedrux
    Thanks for the video, I knew it was possible!
    In the comments there where hundreds of replies regarding servos moving the pens, etc... I believe it's just a matter of time until we see a texture mapping of some kind.
    So I can finish my project and wait for others to come up with a solution. (much faster than I could with my limitted knowledge and budget)

    Maybe my idea is two steps forward in the agenda, but as soon as they come up with a color mixing sharpie-tool, they want to use it in sync with the print.
    Et Voila: Texture mapping.



  • @o_lampe said in Texture mapping with feltpen carousel?:

    Maybe my idea is two steps forward in the agenda...

    Let's get crazy and talk about step three in my agenda:
    Build a Delta printer onTop of my CoreXY and attach an effector that holds the feltpens and solenoids. (No carousel required)
    Then print a layer with CoreXY & park the printhead.
    Then dye the perimeters with the Delta using one felt pen at a time. The data is extracted from the original gcode and can include mixing colors and patterns.
    Then park the Delta and go on printing.

    Print-dye-print-dye (or PDPD) as I'd like to call it in my biography 😉

    Will it require two Duet boards or is it just a matter of toolchange?
    I wouldn't care since this is IMHO the best way to get brilliant color texture mapping without a multicolor mixing extruder.


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