Pen plotter attachment for Prusa MK4

prusaprinters

This is a attachment that that turns your Prusa MK4 into a pen plotter. It clips on to the hotend fan and requires no disassembly of the printer toolhead.It's fairly rigid and can plot fine details (e.g. printed text) with a fine tip ball-point pen.You'll need3x M3 threaded insert (max 4mm deep)3x M3 screw 6mm4x M2 threaded insert (max 4mm deep)4x M2 screw (length up to you, depending how thick your pens are)a rubber band (or the printed spring part)Toolhead Clip and Spring (if not using a rubber band) should be printed in PETG or better. I got good results with 0.15 mm layer height and 5°C above the default temperature. Other parts can be printed in PLA, though ymmv.Assembly instructionsPress M3 threaded inserts into the Toolhead Clip partAttach the Rail onto Toolhead Clip  with M3 screws.Press M2 threaded inserts into the CarriageAttach the pen/pencil with the screw-on clips. It should be positioned so that the tip of the pen is a couple millimeters below the nozzle when installed. Slide the carriage into the rail and tension it with the rubber band.Clip the whole assembly onto the hotend fanYou can print multiple carriages & pen clips to quick swap the pens for multi-color plots.You can try the attached pikachu.gcode file for a test print. You'll need a paper attached securely onto the print bed (e.g. with strong magnets). To create the gcode for plotting, I used jscut. You can use the following default settings: https://gist.github.com/tibordp/5ed30ad2ba71e5bae9dc89c81df53107IMPORTANT: When creating gcode for the plotter, insert G28 as the first instruction to home the printhead before printing. Notes:The carriage should fit snugly in the rail, but move freely in the Z direction. You may need to apply a small amount of lubricant (e.g. silicone spray) so it doesn't catch with weaker tension. You can also print a looser-fitting version of the carriage that has 0.2mm clearance from the rail if it is too tight.You can leave the attachment on when 3D printing, but it's not recommended, as it may affect heatbreak cooling and input shaping parameters. It should be easy to clip on and off. The Y offset from the nozzle is about 50 mm (depending on the thickness of your pen)Onshape CAD model is available here:https://cad.onshape.com/documents/f6a20d1da26d52ada585dadd/w/3487466d66fbd70d56b143b1/e/e69840e50822861201722fe7?renderMode=0&uiState=6609b83735bd9b645909bc99