Fake Digital Clock

This model is for single extruder printers. If you have ever done a filament change at a certain layer, you can handle this! There are a total of two color changes (three if you count the superfluous one in the very beginning). When it first starts it will ask you to change the filament. You'll want to load the color black. It will print the background, and then ask you to swap filaments. Insert whatever color you want the digits to be printed in, and it will print two layers of the digits, and then it will prompt you to switch back to black to finish the rest.

The model prints face down on the print bed, so ensure your first layer is properly tuned to look good. I used the scroll wheel on my Prusa to slow the print speed down to 50% so the first layer came out even smoother than usual.

In the Printer Settings tab, I copied and pasted the Color Change G-code into the Tool change G-code so it functions like a “Manual MMU”. If you have an actual MMU, you can just use your MMU profile.

Recommended Print Settings

• Printer Settings
  • General - Capabilities - Extruders: 2
  • Custom G-code - Tool change G-code: M600
  • Extruder 1 - Preview - Extruder Color: Black
  • Extruder 2 - Preview - Extruder Color: Green
• Print Settings
  • Multiple Extruders - Wipe tower - Enable: true
• Set model sub-parts named Frame and Stand to Extruder 1, the rest of the pieces to Extruder 2
• 0.2mm layer height
• 0.2mm first layer height
• 15% gyroid infill
• 99 perimeters for all parts of the digits, the standard 2 perimeters for the Frame and Stand
• Optional - 100% flow for first layer (you can change this as it prints the skirt in the Tune menu by pressing the scroll wheel). This might give you a better first layer.
• Optional - Reduce print speed for the first layer to 50% using the scroll wheel to give a better surface finish.

All of these settings should already be set up in the 3mf file. If you would rather hang it on a wall, instead of standing it up on a desk, you can delete the Stand sub-part in the list on the right before slicing and printing, or just use the fake-digital-clock-single-extruder-without-stand files.

If you have a MK3S, or MK3S+ feel free to use the provided G-code.

Manual MMU Tips and Tricks

I typically hold a sheet of paper below the extruder when it does the color swaps, and I have a pair of tweezers handy to grab any filament still stuck to the nozzle after a color swap. You can even wipe the tip of the nozzle with a clean section of the paper if you are quick. Just don't accidentally shove the big pile of filament that it extruded onto the paper up onto the nozzle!

If you are using the scroll wheel to slow the print down for the first layer, keep in mind that it will reset back to 100% after a color swap, so while it is printing the wipe tower, that's when you should slow it back down if you want a higher quality first layer.

If you notice any stringing that is across the segments of the digits before those print, you can quickly dab them up using a piece of blue painter's tape while it's printing. If they don't come off with a quick dab, you can try a gentle swipe with the painter's tape. Just avoid the hot extruder!

If you want an in-depth look at how to extrude multiple colors on a single layer, I highly recommend this video by HackMonkey.

Please Share Your Makes

I'd love to see your makes, so don't forget to like and post a photo! If you have any other ideas on how to get a super-clean first layer, please let me know.