> For the complete documentation index, see [llms.txt](https://tools.desmoinesmaker.space/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://tools.desmoinesmaker.space/tool-areas/3d-printing/mk4s-and-mmu3.md). # MK4S and MMU3 ## About
{% hint style="info" %} The MMU3 is open for training and general use. {% endhint %} ## Approved Materials Due to the loading and unloading process being very sensitive, the following materials **ARE PROHIBITED**: * Flexible Filament * Glow in the Dark Filament * Filled Filaments (wood, CF, metal, carbon fiber, etc) * "B" grade filament from extrusion transitions Additionally, the list of approved filaments is **limited to**: * ABS/ASA, PLA, and PETG from Hatchbox, Overture, Push Plastic, 3D Fuel, IC3D, Prusament, ColorFabb, Polymaker, Essentium, HSP Layer Line, and MatterHackers. Exceptions may be approved with a steward's permission. ## Slicing We use [PrusaSlicer](https://www.prusa3d.com/prusaslicer/) and the built-in profiles for this machine. The [Prusa Knowledge Base](https://help.prusa3d.com/en/category/prusaslicer_204) has additional information on configuration settings and advanced use. ### Multi Material Slicing Visit to learn more about multi material slicing. Members are recommended to use multi-part models so that individual parts can be easily colored. Meshes with distinct faces can also be easily colored with the smart fill multi-material tool in the slicer. {% hint style="warning" %} When printing with one material, select the MMU3 profile and use only one filament, the wipe tower will not be included in the slice. When printing with multiple materials, select the MMU3 machine profile and choose multiple materials. {% endhint %} ## Prusa Connect and PrusaLink [Prusa Connect and PrusaLink](https://help.prusa3d.com/article/prusa-connect-and-prusalink-explained_302608) are wireless options for saving and printing to the Prusa printers at Area 515. PrusaLink is a local network solution for loading and printing wirelessly and each printer has its local IP address and login information posted in the space. Members get access to the local network at Area 515 when they join. Prusa Connect is a full cloud suite which requires members create a prusa3d account and get invited to Area 515's team; this is completed during training. ### Saving to USB MK4 and newer printers use USB storage instead of SD cards. Members can use the USB if they prefer sneakernet. {% hint style="info" %} Please save your files in a folder named after you. Orphaned files may be removed. Feel free to add sub-folders to your folder as needed. {% endhint %} ## Use {% hint style="danger" %} The MMU is prone to jamming with certain filaments. Many issues can be avoided by using good quality filament with minimal moisture content. Consider drying PLA/PETG for a few hours before printing to ensure jam-free operation. {% endhint %} ### Operation The LCD menus are easy to navigate on this printer, and it does most of the work for you. Clicking the encoder wheel in will get you into the menu from the status screen, and rotating it will allow you to navigate the menus. ### Build Plate Always consult the [filament material guide](https://help.prusa3d.com/filament-material-guide) to know which sheet to use with which filament. There are printed guides at the space stacked with the build-plate holder. Using the incorrect filament will permanently damage the sheet. ### Abrasive Materials Abrasive materials, such as filaments with carbon fiber or glow-in-the-dark additives must only be printed on a printer with a hardened nozzle. The MK4S = MMU3 has a standard flow non-hardened nozzle and cannot print abrasive materials. ### Loading/Ejecting Filament Most of the time when using the MMU, you will be either using the `Preload to MMU` menu option or the `Eject from MMU` menu option. `Load to nozzle` and `Unload filament` are often unnecessary, as the printer will load and unload filament to/from the nozzle when it needs to. #### Loading Filament To load filament, orient your spool of filament so that its hub (the hole in the middle of the spool) is parallel to you and the filament would unwind downward. Screw the filament spool holder into the hub with the gears on the right. Place the spool you would like to load onto the appropriate position in the auto-loader and then feed the filament into the tube below the holder. The weighted arm of the auto-loader will raise and gently bounce at the top of its motion. Feed the filament until it is near the MMU. Then, on the printer, select the `Preload to MMU` option in the menu. Choose the position of your filament and in the menu click to cycle through to the type of filament you are using. When you are ready, scroll to the bottom and select the command to submit changes. The MMU will then move the requested slot and be ready for loading. Gently feed filament into the tube until you feel the MMU grab onto it, and then let go and wait for the MMU to finish the loading process. Use a light touch for this, it can be difficult to tell when the MMU has grabbed the filament otherwise. If you have selected multiple filaments the MMU will automatically move to the next position. #### Ejecting Filament Select the `Eject from MMU` option in the menus and then select the material you will be ejecting so the MMU can preheat. Once it is done preheating, the MMU will move the selector out of the way of the filament slot and push filament out of the front of the MMU. Cut the end of the filament off so it doesn't get stuck in the tube and then retract the filament by pulling on it from the spool end. {% hint style="info" %} The MMU will preheat when ejecting in case the filament you would like to eject is loaded to the nozzle. Sometimes jams happen or the MMU looses track of where filament is, so it will always do this to stay safe. {% endhint %} ## Troubleshooting {% hint style="info" %} MMU errors result in the print getting paused. The printer will keep the bed at temperature until you return to resolve the issue so the part won't delaminate. The extruder will be turned off to prevent further issues though. {% endhint %} {% hint style="info" %} Check out the Prusa i3 MK3S [Prusa i3 MK3S](/tool-areas/3d-printing/prusa-i3-mk3s.md#troubleshooting) section for general troubleshooting tips {% endhint %} ### MMU Jams If filament jams in the feed tubes the MMU may not be able to retract it. In this case, the coupling on the MMU may need to be removed to resolve the jam. Please report a jam to the 3D printing stewards. ### Filament breaks in feed tubes Most issues like this can be avoided by using good quality filament that has been properly dried. PLA is particularly susceptible to cracking when exposed to the air for long periods of time. Filament stuck in the guide tubes going into the MMU can be removed by first ejecting the filament in that tube, and then feeding another material like ABS, PETG, or nylon into the tube to eject any leftover pieces of filament. Filament stuck in the feed tube going from the MMU to the nozzle will require some disassembly of the printer. Please contact a 3D printing steward for help with this. ### MMU Error Codes Prusa's website has a full set of troubleshooting guides on the MMU3's error codes. If the error requires maintenance or tools, please consult a steward before proceeding. {% embed url="" %}