Prusa Mk3s Vinyl Cutter

Are you tired of 3d? Wanna go 2d? :)

This is a holder for a drag knife I designed for the Prusa Mk3s so you can cut vinyl. For me, I wanted to make a few stickers for my scuba tanks... and it was really easier than I thought. I designed it to be attached to the hotend fan shroud and be tucked in nicely to the extruder assembly, but not so close as you won't be able to turn the drag knife depth adjustment knob.

3/23 Update: I now have a right and left facing bracket to clear different cooling shrouds. I recently upgraded mine to an "Delta-P fan duct V2" from teookie on printables. Noticed my original bracket would no longer fit. Flipped the bracket and good to go. Enjoy!

Printing suggestions:
If you use PETG, turn your fans on a little (35% or so) and print slowly. The fan bracket is pretty thin and PETG is sticky so it might want to pull it around a bit. Go slow and you'll be fine. Don't worry about the strength of the bracket. It's plenty strong and the main force (if any) is on the lower screw and the top is just there for alignment.

You can leave the bracket on all the time while not cutting... but you should remove the drag knife when not in use. It will hang lower than the nozzle so it's in the way normally.

You'll need:
* This design, of course.
* Inkscape (free)
* J-Tech laser tool plugin for Inkscape, to create the gcode.. (https://jtechphotonics.com/?page_id=1980)
* A suitable cutter. I'm not affiliated at all with this, but here's the cutter I used. It was cheap and had plenty of blades: (https://smile.amazon.com/gp/product/B07G97TL5Z)
* Recommended: A dedicated print bed plate with a tack pad glued to it to make sure the vinyl sticks down uniformly. This helps keep the vinyl flat, but also gives about .5-.7mm of clearance between the knife and build plate... in the off chance you have the knife a little too far out and cut through the vinyl backing. Less chance of breaking something or cutting into the build plate.

Again, not affiliated. This is just what I purchased myself to use:
Cutting mats: https://smile.amazon.com/gp/product/B07RZHYQT5
Spare build plate: https://smile.amazon.com/gp/product/B07LBQ57WV

Here's a video tutorial that was key for me: https://www.youtube.com/watch?v=CuWZWAfBsm8

MAKE SURE YOU EDIT THE LASER.PY file. Can't stress this enough. Also, if you forget the "W" on that G28 command (below), you're going to have a bad day...mmmmkay? If you forget, the printer is going to autolevel the bed... and will rip off the bracket when it goes to do the 4th check as the drag knife sits lower than the print bed initially. The W just means home the axis, but don't autolevel.

This is the header and footer I use in my laser.py file instead of the video's 10 second timer... which doesn't really look nice with the prusa... says "sleep" instead of that nice countdown... eh. Don't need it anyway.

'header': """
G28 W
G90
G0 Z20
M117 Cutting...
""",
'footer': """
G0 Z20
G0 X0 Y210 F10200; present bed
M18
M117 Done.
"""

BEFORE CUTTING...
Ignore the part of the video where he says copy the values from the JTool dialog exactly and it'll work for you -- they won't. He's using a pen which needs a little pressure so he kinda rams the pen into the bed and lifts high to get the pen off the paper. You can do better. The "Laser on" values are FAR too close to the bed. He says .5? Uhh no. I STRONGLY recommend on your first attempt... print with a very high Z to see the printer run around the design first before actually cutting anything.

My Laser ON Command started out being "G1 Z3.5 F1200"... while I watched. I slowly lowered the value and repeated the run until the blade finally contacted the vinyl. I adjusted a bit lower and settled on Z1.5 for me. I have the blade sticking out about 1mm from the cutter. YMMV.

Also, when you're ready to try that first attempt. Keep your finger close to that reset button to make sure nothing will contact. I initially forgot the "W" on the G28 command but managed to catch the printer before contact. Again... DON'T forget to add that!

To secure the knife, I used a single M4 screw and hex nut (fits the design) to clamp the knife. The fan mount uses longer M3 screws (should be a few in the spares bag). If you don't have a suitable M4, a M3 might work (haven't tried though)

If you found this useful, please donate what you think it is worth to my paypal.me. Help cover the time of design.

-