Prusa i3 Dual Extruder Setup Issues

  • I have a Folgertech Prusa i3, on a Ramps 1.4 with Marlin and I use Repetier-Host to control it. I am attempting to convert it to a dual extruder Bowden setup, and I can't seem to get the second extruder to work, although the first works just fine.

    This is my problem:

    I am not getting a reading in Repetier-Host for the thermistor of the second extruder. It is at a constant 100C.
    When I turn on the cartridge heater for the second extruder in Repetier-Host, the cartridge heater does not heat up.

    This is what I have done:

    For the second extruder, I connected the wires from the thermistor to the pins for T2 and the wires for the cartridge heater to D9.
    I have not updated anything in the Marlin firmware.
    In Repetier-Host, I selected that there are two extruders, and a second extruder is indicated under the 'manual controls' tab.

    This is what I have double checked:

    I confirmed the second thermistor works because it indicates a proper temperature reading when plugging it in both T0 and T1.
    I confirmed the second cartridge heater works because it heats up when connected to D10.

    I apologize in advance if this is an amateur question, but I can't seem to find an answer anywhere. If somebody could at least point me in the right direction, or let me know if there is something I did not include in my post, I would really appreciate it, and hopefully it would help somebody else coming across a similar problem.


    i think you would need to recompile the firmware and set `#define EXTRUDERS 2` then `#define TEMP_SENSOR_1 ` etc etc. there are plenty of tutorials on the net

    It sounds like you need to modify various settings for the 2nd extruder. They are in Marlin, mainly in Configuration.h and pins.h. It's a bit of a pain since there are many #ifdef switches for different boards, printers, etc. Be sure you keep spare copies as you work. Try to work out just which #defines are getting applied in your situation, or just change all of (for example) the TEMP_SENSOR_1 #defines. It's tedious but doable.

    @TextGeek I appreciate the comment, and the direction to examine my firmware. That was indeed where my problem was. I now have it working.

    @fukanchik I appreciate the comment, and the direction to examine my firmware. That was indeed where my problem was. I now have it working.

  • Thanks to the comments, I was able to narrow down the specific issues in the firmware. The firmware version was really out of date, so I recommend finding the latest stable version.

    Therefore, I found the latest stable version of Marlin, downloaded it, and created my own edited version. I went line by line in configuration.h and configuration_adv.h, with the old version I had side by side to the newer version, making any and all appropriate changes. Below are the lines I found most important to evaluate when setting up a second extruder.

    Make sure the you have the right board selected from boards.h:

    #define MOTHERBOARD 34

    Make sure the # of extruders is specified:

    #define EXTRUDERS 2

    Make sure the sensor is active:

    #define TEMP_SENSOR_0 6
    #define TEMP_SENSOR_1 6
    #define TEMP_SENSOR_2 0
    #define TEMP_SENSOR_BED 6

    This should be considered:

    #define HEATER_0_MAXTEMP 240
    #define HEATER_1_MAXTEMP 240
    #define HEATER_2_MAXTEMP 240
    #define BED_MAXTEMP 90

    Everything under this comment should be looked at:

    // Preheat Constants

    These would allocate the second extruder for other motors:

    #define DUAL_X_CARRIAGE

    I'm sure there are other parameters I may have missed, and these are specific to my Prusa i3, but I hope this helps out anybody else in the future.

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Content dated before 7/24/2021 11:53 AM