CMYK Prusa XL | Open Source | Research Paper

Hello, here's my personal project I did with Prusa XL printer it comes it an open source software, research paper, and some instructions. I am a second year computer engineering student at community college. This instructables will talk a about my paper and how to do it. Here 's the link to the code, paper, and photo. https://github.com/Cmd-8/CMYK_Prusa

1. Prusa XL 2T - 5T
2. Prusa Slicer
3. PLA filament
4. Computer
5. Time haha

I was at our college fabrication lab when Patrick was printing a trophy with an XL Prusa. The print had different color sections, and when the printer switched colors, it made a purge tower (a small structure printed to clean the nozzle). The fab lab staff and I noticed from a distance that the colors seemed to blend!

That day, I quickly tried to make some prototype with AI that created a Python script to change the G-Code (the printer's instruction language). It didn't work because it gave a red screen on the Prusa. This is a common issue that people trying to add new G-Code to their files have discussed in online forums. This led me to investigate further. The next few days, I researched how to pick up and switch the tool-heads.

I found the Prusa G-Code command document, which showed the tool-head number command "T0." I then looked at the G-code file itself. I searched for "T0" and found commands like "P0 S1 L2 D0" (which parks the tool-head) and "T0 S1 L0 D0" (which picks up the tool-head). Instead of creating entirely new G-Code, I decided to replace the existing "T#" commands. In the slicer (the software that prepares your model for printing), I made two tool-heads switch back and forth every layer. This created a "T" command for every layer, which I could then replace with the specific tool-heads I wanted to use. While I was coding this, I tested out different print settings using this slicer method. I continued to make a couple of variants, experimenting with color changes over time, striped patterns, and randomized sequences.

The color changing involved tool-head sequences, like (T0, T1, T2, T3, T4) which would translate to (1, 2, 1, 3, 4), where each number represented how many layers of each color to print. These would also go through group sequences like (1, 2, 1, 3, 4), then (3, 1, 1, 0, 3), and so on. For color changes over time, I'd set up sequences like (3, 0.25, 0, 0, 0), then (3, 0.5, 0, 0, 0), then (3, 0.75, 0, 0, 0), then (3, 1, 0, 0, 0), before moving to a new set like (0, 3, 1, 0, 0), and so forth.

Step 1: Prepare Your 3D Model

1. Import Model: Load your 3D model into Prusa Slicer. I imported a default box model by right clicking the plate.
2. Make sure 5T or 2T Prusa XL is chosen for printer.

Step 2: Key Print Settings for Blending

1. Layer Height: For the best color blending and to minimize visible layer lines, set your layer height to 0.05mm or smaller. This is crucial for the optical blending effect.
2. Print Speed: Use the "SPEED" preset in Prusa Slicer. This helps the plastic fuse together better.
3. Wipe Tower & Brim: Set the wipe tower to 70mm and the brim to 6mm. These help keep your print stuck to the bed and stable during frequent tool-head switches.

Step 3: Set Extruder Sequence for Color Blending (Prusa Slicer)

This feature in Prusa Slicer is where you control your color mixes.

1. slice the object next.
2. Click the gear icon in the bottom right of the print viewer to open this setting.
3. Click “Set extruder sequence for the entire print”
4. Make sure the layer switching is at 1 layer and minus on the extra tool if not using them.
5. Two-Color Blending (e.g., Light Blue):
6. To blend colors (like blue T1 and white T2 for light blue). This makes the printer alternate T1 then T2, etc.
7. To get more blue, add more T1 layers (e.g., T1, T1, T2). For more white, add more T2 layers.
8. Important Note: The total thickness of your mixed color layers (e.g., T1 + T2) must not exceed 3mm. Go over this, and colors will look separate.
9. At 0.05mm layer height, two colors give you up to 13 different shades!
10. Three-Color Blending (e.g., Light Teal):
11. To add a third color, like green (T3), for a light teal, try a sequence like T1, T3, T2 (Blue, Green, White).
12. Remember the 3mm total layer height limit.
13. Three tool heads (like RGB) can make 19 new colors at 0.05mm!
14. Four to Five-Color Blending (CMYK Fun!):
15. This needs a 4-tool head or 5-tool head Prusa XL. You can use Cyan, Magenta, Yellow, and Black (CMYK).
16. Four colors give you 15 blends; add black/white, and you get 30 (total 54 shades with 5 filaments)!
17. Stripes & Random Blending: In the same menu, you can also create random color sequences or define stripes by changing the "layer change" value (e.g., 3 or more layers per color).

Step 4: Slice and Print!

1. Reslice: Always reslice or reload your object after changing settings. This updates the G-Code for your printer.
2. Watch Out For:
3. Small Bumps: Might mean your tool heads need calibration (alignment).
4. Color Bias: One side of your print might have more of a certain color, especially on larger models.
5. White/Black Dominance: These colors are strong! You might need to add more layers of the other colors to balance them out.
6. Print Failures: More complex or larger prints can be trickier to get right.

Step 5: After Printing (Future Exploration: Annealing)

"Annealing" is a technique where you heat the finished print. This can help fuse the colors even more, potentially reducing visible lines and improving the overall color mix. It's something exciting for future experiments!

My tests show that color blending with multi-tool head printers like the Prusa XL has huge potential! Keeping your machine calibrated and optimizing settings are key to good results.

Key findings:

1. Layer Height: 0.05mm or smaller consistently gave the best color quality and fewest print issues.
2. Print Speed: The "SPEED" preset in Prusa Slicer worked better for blending, likely due to better plastic fusion.
3. Print Size: Smaller, simpler prints were more successful.
4. Color Dominance: White and black filaments tend to overpower other colors, so adjust layer ratios carefully.
5. Print Time: Adding a second color adds more print time, but adding more colors after that doesn't significantly increase it further.

There are exciting next steps for color blending:

1. Smarter Software: Imagine slicers that show you exactly what mixed color you'll get, or even let you "paint" colors onto your model layers!
2. Better Printers: Future printers will have even faster and more precise tool-head switching.
3. Material Blending: We could even blend different types of plastic to create parts with unique properties, like being strong in one area and flexible in another!
4. Annealing: More research into annealing could lead to perfectly smooth, line-free color transitions.

While I've had success with color blending, there's always more to learn and improve. That's the fun of 3D printing!

Annealing source

https://blog.prusa3d.com/how-to-improve-your-3d-prints-with-annealing_31088/