Cat Address Numbers - Two Colors (MMU not required)

House address numbers using cat silhouettes.  Two colors are used, with a screw in retention wedge to keep the numbers in place without any visible screws.  The numbers are approximately 155mm high.  

The prints require a total of four color changes at the beginning, before reverting to a single color, make this an easy print for those of us that do not have an MMU.  Instructions for printing without an MMU follow.  As these will typically be outside, using PTEG or ASA is recommended over PLA.

Retention wedges should be printed at 100% infill.  Lower infill can be used, but be careful when screwing them in as they could collapse.  The cat numbers can be printed at 10% infill.

Screws should be tapered head, size #8 or M4.  Whenever possible, the retention wedges have been located directly above the center of gravity (COG).  Where they could not be installed above the COG, it was placed below the COG, but centered vertically.

Final tightening should be done with a screwdriver to allow for accurate angle adjustment.   Final tightening with an electric screw driver may make it difficult to set the retention wedges properly.

Optional single color mounting guides have been included to facilitate the screw location.  These are relatively quick prints that hold the retention wedges in place and allow for the screws to be tightened, while still seeing the number layout.

The numbers are intended to be printed face down, so that the numbers look reversed until they are pulled from the printer.  The black and white cat versions are loaded at the same time.  A message stating “Multi-Part object detected” should pop up.  Choose “yes” to load the files and treat them as two colors.  See below for instructions printing two colors without an MMU.

Dual color printing instructions using PrusaSlicer without an MMU.  Skip this if you already know how to print using two colors.

There may be another way to do this, but after some research and some banging of my head against a wall, this ended up working for me.  Please note that these changes need to be completed before importing the black and white colored cats for the slicer to identify them as multi-part objects.  

This may seem like a lot of information, but I want to be sure that it is easy to follow and have provided a lot of detail.  Let me know if anything is confusing and I'll try to clarify the process.

Set up Filament: When the “Single Extruder Multi Material” option is selected in the dual print process, the only filament setting available shows up as “- default -”.  Before proceeding, you will need make a copy the relevant filaments and edit the dependencies as follows:

1. In the upper right corner of PrusaSlicer, select “Expert Mode”.  This will be necessary to access the needed settings.  The other two options shown will be “Beginner Mode” and “Normal Mode”.

2. Under the Filaments tab, select the material that you will use for the print.  In the example below, Overture PETG is selected.  Click the  icon and save the filament as a user preset with an appropriate name.

2. Still in the Filaments tab, select Dependencies and look at the “Compatible printers condition”.  Delete the entire line.  If you have been printing with that Filament in the past, it is compatible for the dual color prints.

Before:

After:

Set up printer

• Under the Printers tab, General: set Extruders to 2 and select the “Single Extruder Multi Material”.  Selecting the Single extruder multi material will hide all of the filaments, other than the ones set up above, as they will now be considered incompatible.

• Under the Printers tab, Custom G-code: Scroll down to “Tool change G-code” and insert “M600”, without the quotes.  M600 the G-Code command that initiates the filament change procedure. Save the Printers Tab with another name.  For example, “2 color original Prusa”.

Set up Print Settings

• Under the Print Settings tab, Multiple Extruders: deselect the wipe tower “Enable” (turn it off).  Save the Print Settings to another name.  For example, “0.15mm Quality @MK3 - Multi Color”.  

Check/select filament

• Select the Filaments tab and verify that the correct material is being for both Extruders. 

Time to import your files for printing.

• Save the numbers that you want to print.  Make sure to save both the black and white files of the cats.  In PrusaSlicer, import both of the files at the same time.

• If both black and white files are opened at the same time, a Multi-Part object message will pop up.  Select “Yes”

• The number should be reversed, with the cutout for the retention wedge showing up at the top.

• On the right-hand side, you will see the two files associated with the extruders.  In order to make the identification of each part easier, Select the filament for each color by clicking on the color under the “Filament:” section.  For the black cat portion, you should use a dark color, such as dark blue instead of black, since black will be difficult to see in the preview tab.  The white cat color can be set to white. 

• The stl file associated with extruder 1 will be the first to print.  For info, the extruder can be changed by right clicking on the stl file and selecting “change extruder”.   If you start with the blackcat file as extruder 1, there will be one less tool change.
• I suggest using variable layer height to reduce the print time, but it is not necessary.

Slice the Cat and print

• Export the G-code and load it into the printer.
• Make sure you have the two colors ready to go.
• Start the print.  It does not matter which filament is loaded in the printer to start.  It will unload the filament after bed leveling.
• The head will move the front right corner of the bed, start beeping, and prompt with “Please press the knob to unload filament”.  Click on the knob and remove the filament.
• After it unloads a message will appear “Was filament unload successful?”
• After clicking yes, the message “Insert filament and press the knob” will show.
  • Make sure the end is cut (not globby) and insert the first color to load.  
  • If it doesn't load properly, don't worry.  Just wait until the message and select unload filament and try again.
• Once the filament is loaded properly click “Changed correctly” and the head will extrude a little more material before moving. Grab hold of the little glob when the head starts to move and give it a quick pull to disconnect the string from the print head. This produces a cleaner print.
• Once the color is done, it will move back to the front right corner to swap colors again.

For these prints, there are two layers of black, with the rest of the prints in white.  You will need to babysit the process for the first 15-20 minutes and then let it complete the print on its own.  You will know the color changes are done when the border color starts overlapping the inner color.

I've included PLA and PTFE versions of each print, just in case.

That's it! Please post a review if you like the information and files I've created.  Enjoy!