MK4 Electronics Box Cover (Manual MMU)

2024-07-29 Edit: When trying to use this technique in PS2.8.0 I started having weird extra extrusions happening right after color changes. I finally tracked it down to a deretraction happening due to a new setting for retraction length when tools are disabled. I've added the setting that needs to be zeroed out to the basic gist, below, and modified the 3mf file.

When printing this electronics box cover, I decided that I wanted the PRUSA name to show better than just being embossed into the print. I've used this manual MMU technique on other prints for the same effect so I decided to use that same technique here. (FWIW I don't have an MMU on my MK3.) If you are planning on printing on a different printer (MINI, MK4, XL, etc), you can use the following to adjust/create your own profile. If your printer doesn't support the M600 filament change command, adjust the tool change g-code to fit your printer.

The basic gist of the technique is as follows:

• Make sure you have “Expert” mode enabled.
• In Printer Settings/General increase the “Capabilities/Extruders” value to the number of different colors you plan on using. 2 in this case.
• Make sure “Capabilities/Single Extruder Multi Material” is not checked.
• In each of the "Printer Settings/Extruder #" pages, scroll down to the bottom and make sure “Retraction when tool is disabled (advanced settings for multi-extruder setups)/Length” is zero.
• In Printer Settings/Custom G-code insert the following into “Tool change G-code”:

{if layer_z>0 }
M117 Change to color {next_extruder}
M600; Filament change
{endif}

I've found that on my MK3 that if I don't use the if statement then there will be a filament change inserted between the purge line and the start of the print. Also, the M117 message will be over written by the filament change wizard once the extruder moves to the filament change location, so be sure to watch for the message if you use more than 2 filaments to know what color is up next.

• In Print Settings/Multiple Extruders make sure “Wipe tower/Enable” is not checked.
• Once you have assigned the different colors, if you have more than 2 colors create a chart to know which color number (starting with zero) is which spool of filament you plan to use.

When printing, you have to physically monitor the print so you can see the next color number and manually change the filament. Remember, on the MK3 M600 color change routine, there will be a small amount of extrusion when the extruder is returning to the print after you have confirmed that the color extrusion looks good. AFAIK this is a purge to help build the proper pressure for printing inside the extruder. I wait to pull the color change purge (and priming purge) off of the extruder until the nozzle is just about to touch the print.

When uploading this remix I spotted a similar one by @akashrpatel for use with an MMU2, so I cribbed his remix name.