I've remixed my old remix of the MK3S+ extruder modded for the Mini+. My old remix was a little bit flimsy. It is now a 2 part print. I've removed the filament sensor cavity as I prefer using the original filament sensor on the Mini. This way, no need for a custom firmware or messing with wiring to have the filament sensor inverted. I was not interested in the Bondtech extruder as some are still experiencing the same issues as with the original one. My way is much cheaper and it is dead silent and prints awesome! No load/unload issues. Compatible with Input Shaper.
*** For those interested in the old extruder (with filament sensor): https://github.com/CybergNetwork/Prusa-Mini-Mods/blob/main/Dual_Drive_Extruder_Prusa_Mini_Rev6.stl
PARTS
1 x MINIKS+ Extruder & Idler Door
2 x PC4-M10 Pneumatic Bowden Coupler
2 x M3-10
4 x M3-40
1 x M3 Hex Nut
1 x MK3 Bondtech Extruder Drive Gear Kit (1 x Spring, 2 x Bondtech drive gear, 1 x M3 Adjusting screw, 2 x Bearing & 1 x Shaft)
2 x Small tie wraps
1 x 335.5mm PTFE tube (Not shown on picture)
TOOLS
1 x 3mm Hex Key
1 x 10mm Socket
1 x 1.5mm Hex Key
1 x Sharp Knife
COST
Around $14 USD (Amazon)
*Bondtech Extruder is $75 USD (If in stock and it is NOT as reliable as my remix)
FIRMWARE
Minimum 4.3.3 for Experimental Settings or Minimum 5.1.0-Alpha1 for Input Shaper.
INSTRUCTIONS (Before you carry on with the instructions, I am assuming that you have removed the original extruder from the Mini)
Step 1 - Clean up Parts
Clean up the printed parts. Ensure that residues are removed from any filament path or holes on the extruder and idler door (recommend using the 1.5mm hex key and sharp knife)
Step 2 - Install 2 x PC4-M10 Pneumatic Bowden Coupler
Finger tight the PC4-M10 couplers to ensure alignment. Final tightening is done using a 10mm socket. Do NOT overtight!
Step 3 - Install 2 x Bearing + Shaft + Bondtech Drive gear & M3 Hex nut on Idler Door
Perform Step 27 to 29 from the MK3S assembly instructions: https://help.prusa3d.com/guide/5-e-axis-assembly_28536#29848
Step 4 - Install 1 x Bondtech Drive gear on the Stepper Motor
Insert the Bondtech Drive gear on the Stepper Motor shaft. Before tightening, ensure the screw is on the same side as the flat surface on the shaft. Using a 1.5mm hex key, tighten the screw, but be careful, you can easily strip it (We will adjust proper alignment of the filament path and the Bondtech gear later).
Step 5 - Assembly of the Stepper Motor to the Extruder Body (and Idler Door)
Insert the Stepper Motor inside the Extruder (ensure the wires are facing downward).
Add the Idler door to the Extruder.
Insert 4 x M3-40 screw and tighten them all in an X patern (Do NOT overtight). Use a 3mm Hex key.
Allign the Bondtech Drive gear with the filament path (Do NOT overtight). Use a 1.5mm Hex Key.
Confirm allignment of the Bondtech Drive gear by inserting a piece of scrap filament or the handy 1.5mm Hex Key through the PC4-M10 coupler. Make adjustment as necessary. Close the Idler door.
Insert the Idler Spring and M3 Adjusting Screw. Use a 3mm Hex Key.
Here is how much thread coming from the Hex Nut (yours might be slightly different).
Step 6 - Extruder installation & Cable management
Using a 3mm Hex Key and 2 x M3-10mm screws, secure the Extruder to the axis (Do NOT overtight).
Route 2 x Tie Wraps as shown on the picture.
Secure wires and ensure the locking piece of the tie wrap is facing back (yellow circles). If not, the Part cooling fan will interfere and the hotend will be restricted on its axis. Cut any excess from the tie wrap.
Step 7 - PTFE tube installation (I do not provide instructions on inserting the PTFE tube in the hotend as you may be using a 3rd party hotend. Refer to the hotend user manual).
*Don't forget to chamfer both end of the PTFE tubes and remove residues left inside
Insert the PTFE tube in the PC4-M10 coupler (push until you feel a resistance). This is the side where your filament is coming from the spool.
Insert the 335.5mm PTFE tube in the PC4-M10 coupler (push until you feel a resistance). This is the side where the filament is coming from the extruder to the hotend.
Insert the PTFE tube in the hotend
Step 8 - Change the Extruder Steps
On the Prusa Mini+ LCD screen, go in Settings. Push the Knob for about 1-2 seconds. You are now in the Experimental setting menu. Under Extruder Step, change the value to 139. Under Extruder Dir, ensure it is set to Prusa. Don't forget to save the new value. The printer will restart.
Step 9 - Filament Load/Unload
Load you favorite filament. If no noise is coming from the extruder, the idler screw is properly adjusted. If necessary, make any adjustment. Now it is time to unload to confirm adjustment.
Step 10 - Yeaahhhhh!
You are ready for your 1st print!
Demo (sorry for the background noise coming from my server rack)
The author remixed this model.
Removed the filament sensor cavity. Combined all parts but Idler door to make it a 2 part print.