Panning Dual Hotend for Prusa I3

thingiverse

Hey Guys, I've designed a panning dual hotend for my printer. It can lift the unused nozzle to prevent contaminating the printed filament and reduce oozing. The filament cooling system is integrated as an air duct in the slider. You'll need to print the parts carefully, as they have some critical points. To build this system, you'll also need to purchase some additional parts: 2x 50mm Fans 3x IGUS RJMP-1-8 Linear Bearings 1x Graupner DES586BB Digital Servo Some M3 & M4 Screws 2x Hotends 2x Aluminium bracket 30x30x2 1x LJC12A3 Proximity Switch Some High-Temperature Silicone You can watch a video of the printhead in action on YouTube: https://www.youtube.com/watch?v=6Enaf-HHfRo Note: The nozzle might not move to its limit stop. If this is the case, it's possible that the servo isn't strong enough to bend the cables and filament PTFE tubes. Simply make the cable loop a bit larger and use longer filament tubes. Software Implementation There are two ways to implement this system in software: The first method is to use a tool change command like M340 P0 S[next_extruder] in Slic3r. You can then replace the S0 or S1 with a post-processing script. Here's an example of how to do this under Linux or OS X: ```bash #!/bin/sh file="$*" echo "Post-processing G-code file: $file" # Replace S0 sed -e 's/M340 P0 S0$/M340 P0 S1570/g' $file > "$file.tmp" # Replace S1 sed -e 's/M340 P0 S1$/M340 P0 S1850/g' "$file.tmp" > "$file" # Remove tmp file rm "$file.tmp" ``` The other way is to modify the firmware of your printer. I'm using the Repetier firmware, and only two small modifications are necessary. Add these lines to your configuration.h: ```c #define T0_SERVO_POSITION 1570 #define T1_SERVO_POSITION 1850 ``` These values will depend on how you assemble the servo. The other modification is in the "commands.cpp" file near line 2450: ```c else if(com->hasT()) // Process T code { Commands::waitUntilEndOfAllMoves(); Extruder::selectExtruderById(com->T); } // Addition for Panning Hotend if(com->T == 0) HAL::servoMicroseconds(0,T0_SERVO_POSITION,0); else if (com->T == 1) HAL::servoMicroseconds(0,T1_SERVO_POSITION,0); ``` Have fun! Henning