Prometheus System - User Guide

Table of Contents

      1. User Guide
        1. Connecting Hardware and Electronics
        2. Firmware Setup (Marlin and Repetier)
        3. Host/Slicer Setup (Repetier Host - Cura)
        4. First Print (Repetier Host - Cura)
        5. Printing Temperatures
        6. Part Cooling
        7. Cleaning the Nozzle
        8. Cleaning the Drive Gear
      2. Troubleshooting
        1. Underextrusion
        2. Overextrusion
        3. Oozing
        4. Delamination
        5. Jamming
        6. Stringing
        7. Purging
        8. Switching
      3. CAD Drawings
        1. Prometheus V2 Hot End
        2. ProFeeder
        3. ProStruder

User Guide

NOTE: This User Guide is a work-in-progress. Please check back regularly to see the most recent version.

Connecting Hardware and Electronics

  • Wire the 25mm hot end Cooling Fan and the (2) 40mm extruder Cooling Fans directly to your power supply, red wire = (+), black wire = (-). This will ensure that the Cooling Fans runs continuously at full speed to provide optimal cooling for the hot end and extruders. DO NOT connect the Cooling Fan to your controller board "Fan" output as this output is used to control fans for cooling the printed part. Please ensure that these fans are always on!
  • Wire the Cartridge Heater and Thermistor to your controller board. This Heater MUST run on the rated voltage!
  • Plug the 4-Pin Stepper Motor Cable from each extruder into the pins for extruder 1 (E0 on RAMPS 1.4) and extruder 2 (E1 on RAMPS 1.4) on your controller board. The wiring will be BLACK = 2B, GREEN = 2A, RED = 1A, BLUE = 1B. If the stepper motors turn in the wrong direction, you can easily reverse the direction by reversing the wiring: BLUE = 2B, RED = 2A, GREEN = 1A, BLACK = 1B. If the above motor wiring does not work for you, try BLACK = 1A, GREEN = 2A, BLUE = 2B, RED = 1B.
  • Secure the ProStruders to the frame of your printer and mount the Prometheus V2 Hot End to your carriage/end effector. For delta printers, mounting the ProStruders in a "flying" configuration with short bowden tubes will decrease hysteresis and increase the quality of your prints.
  • Below is a picture of the Prometheus System mounted on one of our custom delta printers with flying extruders and short bowden tubes:

  • While we suggest mounting the ProStruders in a "flying" config for delta printers, we cannot provide detailed instructions for creating a flying extruder setup because every printer is different. A simple approach would be to buy some bungee cords and wrap one end around the ProStruder and attach the other end to the top of your printer frame.
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Firmware Setup (Marlin and Repetier)

The following steps outline the firmware configuration for Marlin and Repetier Firmware:

  • Configure your firmware for the Semitec 104-GT2 Thermistor
    • Marlin - Configuration.h:
      • #define TEMP_SENSOR_0 5

 

      • // #define HEATER_1_MINTEMP 5

    • Repetier - Configuration.h:
      • #define EXT0_TEMPSENSOR_TYPE 8

      • #define EXT1_TEMPSENSOR_TYPE 8

      • Set EXT1_TEMPSENSOR_PIN equal to EXT0_TEMPSENSOR_PIN

    • Smoothieware: temperature_control.hotend.thermistor Semitec
    • RepRapFirmware: Beta value = 4267K.
  • Configure your firmware for Dual Extrusion:
    • Marlin - Configuration.h:
      • #define EXTRUDERS 2

    • Repetier - Configuration.h:
      • #define NUM_EXTRUDER 2

  • Enable "cold" extruder moves and lengthy extrusion:
    • Marlin - Configuration.h: Disable the following lines of code using //:
      • // #define PREVENT_DANGEROUS_EXTRUDE
      • // #define PREVENT_LENGTHY_EXTRUDE

    • Repetier - Configuration.h: 
      • #define MIN_EXTRUDER_TEMP 0

      • #define EXTRUDE_MAXLENGTH 400

  • Set 500 steps/mm (1/16 microstepping) or 1000 steps/mm (1/32 microstepping) for the extruder steps, 60 mm/s for the X-axis jerk, and 15 mm/s for the E-jerk:
    • Marlin - Configuration.h: 
      • #define DEFAULT_AXIS_STEPS_PER_UNIT {X-STEPS, Y-STEPS, Z-STEPS, 500, 500}
      • #define DEFAULT_XYJERK                                      60.0
      • #define DEFAULT_EJERK                                        15.0

    • Repetier - Configuration.h: 
      • #define EXT0_STEPS_PER_MM 500
      • #define EXT0_MAX_FEEDRATE 100
      • #define EXT0_MAX_START_FEEDRATE 15
      • #define EXT0_MAX_ACCELERATION 2000
      • Repetier EEPROM settings:
      • #define EXT1_STEPS_PER_MM 500
      • #define EXT1_MAX_FEEDRATE 100
      • #define EXT1_MAX_START_FEEDRATE 15
      • #define EXT1_MAX_ACCELERATION 2000
      • Repetier EEPROM settings:
      • #define MAX_JERK 60.0
      • Repetier EEPROM settings:
  • Tune the stepper driver current to about 1.2A for the ProStruders:
    • Manual Tuning:
      • Start at a low current and increase the current gradually until the stepper motors start skipping steps, and then reduce the current slightly to ensure that the stepper motors will operate consistently without skipping steps.
    • Marlin - Configuration_adv.h:
      • #define DIGIPOT_MOTOR_CURRENT {185,185,185,215,215}

    • Repetier - Configuration.h:
      • #define MOTOR_CURRENT {185,185,185,215,215}

  • Upload the updated firmware to your electronics board.
  • Connect to your printer and run M303 PID Autotune:
    • Repetier Host - Manual Control Panel:
      • G-Code: M303 E0 S250 C8
  • Copy the final values for Kp, Ki, and Kd from the PID Autotune and enter them into your firmware:
    • Marlin - Configuration.h:
      • #define DEFAULT_Kp  21.45
      • #define DEFAULT_Ki  2.34
      • #define DEFAULT_Kd  49.2

    • Repetier - Configuration.h:
      • #define EXT0_PID_P  21.45
      • #define EXT0_PID_I   2.34
      • #define EXT0_PID_D  49.20

  • Re-upload the firmware to your electronics board.
  • NOTE: The thermistor is delicate so you should not attempt to remove the thermistor after heating the hot end. If you need to reassemble the hot end just unscrew the heat sink to avoid removing the thermistor or heater cartridge.
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Host/Slicer Setup (Repetier Host - Cura)

  • These instructions outline the steps for configuring Repetier Host and Cura for dual extrusion with the Prometheus System. Please input all values EXACTLY as shown in the images below, unless otherwise highlighted in RED text.
  • NOTE: Simplify3D support is still in development. The Simplify3D software still has some quality issues with dual extrusion prints and we are working with the Simplify3D team to sort these out as soon as possible. For now you will have to use Repetier Host and Cura to slice your models.
  • Install Repetier Host with CuraEngine Slicer
  • In Repetier Host, open Printer Settings - Printer and set the manual extrusion and retraction speed:

  • Open Printer Settings - Extruder and configure your settings for dual extrusion:

  • NOTE: For all of the G-Code scripts below, please copy the code highlighted in RED as this is the most up-to-date version of the scripts. The G-Code shown in the images may be out-of-date and it is only meant to be used as a visual reference. 
  • Open Printer Settings - Scripts and configure Script 1 (PURGE-RETRACT) and Script 2 (FEED). Copy the updated G-code below:
    • PURGE-RETRACT
      G91  ; relative positioning
      G1 E20 F600  ; 10mm/s purge
      G1 E-20 F3000  ; 50mm/s retract
      G1 E-14 F1500  ; 25mm/s reshaping
      G4 P1000  ; 1s cooling period
      G1 E-110 F1500  ; 25mm/s long retract

    • FEED
      G91  ; relative positioning
      G1 E130 F1500  ; 25mm/s feed
      G1 E5 F300  ; 5mm/s feed

  • We will now configure the settings for Cura. You can simply download and import the Cura - Print Settings.rcp file included with the Purge Trail Base (0.3mm) STL download. The Cura print settings are also outlined in the steps below.
  • In the CuraEngine settings, configure the Print - Speed and Quality settings:
  • NOTE: All objects should be printed at 60mm/s with 0.2mm layer height and a 0.3mm first layer.

  •  Configure the Print - Structures settings:

  • Configure the Print - Extrusion settings:

  • NOTE: For all of the G-Code scripts below, please copy the code highlighted in RED as this is the most up-to-date version of the scripts. The G-Code shown in the images may be out-of-date and it is only meant to be used as a visual reference. 
  • Configure the Print - G-Codes - Before Extruder Switch settings. Copy the updated G-code below:
    • Before Extruder Switch
      G90  ; absolute positioning
      G1 X25 Y60 F{TRAVEL_SPEED}  ; move to purge zone
      G1 E0 F4800  ; feed filament
      G91  ; relative positioning
      G1 X-50 E5 F6000  ; purge trail
      G1 Y1 F6000  ; Y shift
      G1 X50 E5 F6000  ; purge trail
      G1 Y1 F6000  ; Y shift
      G1 X-50 E5 F6000  ; purge trail
      G1 Y1 F6000  ; Y shift
      G1 X50 E5 F6000  ; purge trail
      G1 Y1 F6000  ; Y shift
      G1 X-10 E-20 F1500  ; drip trail
      G1 E-14 F1500  ; 25mm/s reshaping
      G4 P1000  ; 1s cooling period
      G1 E-110 F1500  ; 25mm/s long retract

  • Configure the Print - G-Codes - After Extruder Switch settings. Copy the updated G-code below:
    • After Extruder Switch
      G91 ; relative positioning
      G1 E130 F1500 ; 25mm/s feed
      G1 X-40 E4 F900 ; prime trail
      G90 ; absolute positioning
      G92 E0 ; reset extruder position

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First Print (Repetier Host - Cura)

  • Our first print will be the simple DisTech Dual Color Keychain featured in our Kickstarter campaign:

  • Slice the objects using CuraEngine Slicer. You should see a print preview that looks like this:

  • Note that the Purge Trail needs to align with the Purge Trail Base as shown:

  • You can adjust the X and Y position of the purge zone by changing the coordinates in the line of G-Code highlighted below and re-slicing the model:

  • You can adjust the size of the Wipe and Prime Tower (purge volume) by changing the highlighted value below. 45 mm^3 is usually more than enough purging for clean color transitions. However, if you are printing support material or colors with high contrast (ie. Black and White), you may want to increase the purge volume.

  • The control panel can be used to manually control the extruders. The red boxes highlight the extruder selection drop down menu and the buttons for Script 1 (PURGE-RETRACT) and Script 2 (FEED):

    • Script 1 (PURGE-RETRACT): runs the first half of the filament switching G-Code which rapidly purges the hot end and retracts the filament to eliminate stringing. The filament tip should look like the image below after it is retracted using Script 1. *Note*: Remember to dry your filament overnight before printing to ensure reliable filament switching without stringing!

    • Script 2 (FEED): runs the second half of the filament switching G-code and feeds the filament back into the hot end after it has been retracted using Script 1.
  • NOTE: We HIGHLY recommend you start by printing single color objects to determine the optimal temperature settings and extrusion multiplier for your filament. This will simplify the initial troubleshooting process.
    • NOTE: We HIGHLY recommend you start your dual extrusion prints using ABS filament. ABS has low melt flow viscosity so it is easy to purge on each filament switch (Colorfabb nGen is also a good choice). This will simplify the initial troubleshooting process. 
    • NOTE: You MUST dry your spools of filament overnight before printing. Excess moisture leads to stringing and swelling of the filament tip, both of which cause jamming during filament switching. We suggest using the drying method outlined on the Taulman 3D website
      • Prepare to start your print:
        1. Heat the Hot End and Heat Bed to the temperatures required for your thermoplastic.
        2. Select Extruder 2 from the extruder selection drop down menu.
        3. Load filament into ProStruder #2 and slowly extrude the filament using the manual controls until it starts extruding from the nozzle tip.
        4. Send Script 1 using button #1 on the Control Panel to purge and retract the filament loaded in ProStruder #2.
        5. Load filament into ProStruder #1 and slowly extrude the filament using the manual controls until it starts extruding from the nozzle tip.
        6. Wipe the extruded strands of filament from the nozzle tip.
        7. Start your dual extrusion print!

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        Printing Temperatures

        The printing temperature can have a significant impact on layer adhesion, bridging, overhangs, and "ooze" (stringing). Higher printing temperatures generally result in stronger layer adhesion, but at the expense of a loss of performance in other aspects of your print.

        The effects of printing temperature are listed in the table below:

        Change in Printing Temperature Layer Adhesion Bridging/Overhangs "Ooze" (stringing) Maximum Feed Rate
        Increased Stronger Worse Increased Slightly Increased
        Decreased Weaker Better Decreased Slightly Decreased

        A range of recommended temperatures for printing various thermoplastics with the Prometheus System are listed below:

        Thermoplastic Recommended Printing Temperature
        PLA, PVA 200 C - 220 C
        PET, PETG 230 C - 250 C
        ABS 240 C - 260 C
        Nylon (Taulman) 250 C - 270 C
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        Part Cooling

        Enabling a part cooling fan can have a positive impact on the quality of bridges, overhangs, and corners of your print, especially when printing PLA. However, there are also some detrimental side effects of a part cooling fan, especially with regards to layer adhesion. 

        The below table lists the effects of part cooling on a print:

        Change in Part Cooling Layer Adhesion Bridges, Overhangs, and Corners
        Increased Weaker Better
        Decreased Stronger Worse

        In general, PLA prints benefit from increased part cooling with minor negative effects on layer adhesion. On the other hand, optimal ABS print results are achieved with minimal part cooling. Excessive part cooling on ABS prints can cause severe layer delamination. 

        *Important*: If using a part cooling fan you must ensure that the air flow is NOT blowing over the nozzle tip. Excessive cooling of the nozzle tip can result in inconsistent extrusion and increased extrusion pressure.

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        Cleaning the Nozzle

        The Nozzle can become clogged from foreign debris in your filament or from dust that has accumulated on the filament. The symptoms of a blocked nozzle are inconsistent extrusion and periodic clogging which can lead to "filament grinding" and "air printing".

        Please DO NOT:

        • Soak the nozzle in a solvent
        • Burn the nozzle with a torch
        • Hit the nozzle with a hammer (I am not sure why anyone would do this?? but just don't...)

        The solution is the "Cold-Pull" method. (PLA Pipe Cleaner method). This involves heating the hot end slightly above the Tg of the plastic and pulling the entire length of filament out of the Melt-Zone. This conveniently removes any debris in a non-destructive manner.

        The PLA Pipe Cleaner method is detailed here on NopHead's Blog.

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        Cleaning the Drive Gear

        • The ProStruder Drive Gear can be removed for cleaning by loosening the set screw using the M1.5 Hex Wrench as shown:

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        Troubleshooting

        NOTE: This Troubleshooting guide is a work-in-progress. Please check back regularly to see the most recent version.

        Underextrusion

        • Do you have your extruder steps/mm set to 500 for the ProStruders?
        • Have you measured the correct diameter of your filament using a caliper and entered that number into your slicer settings?
        • Do you have your extrusion multiplier calibrated correctly?
        • Have you ensured that your part cooling fans are NOT blowing air over the nozzle tip? This causes excessive cooling of the nozzle tip and is the most common cause of underextrusion and jamming.

        Overextrusion

        • Do you have your extruder steps/mm set to 500 for the ProStruders?
        • Have you measured the correct diameter of your filament using a caliper and entered that number into your slicer settings?
        • Do you have your extrusion multiplier calibrated correctly?
        • Do you have part cooling fans set up to cool the object as you print each layer? If layers are printed very quickly, heat buildup can cause deformation of the printed object and give the impression of overextrusion.

        Oozing

        • Have you properly set up your retraction? You should have the following settings configured for your ProStruders:
          • Retraction Jerk (Start Speed) = 15.0 mm/s
          • Retraction Speed = 80mm/s
          • Retraction Acceleration = 2000 mm/s^2
          • Retraction Length = 4mm (3mm to 4mm is usually enough retraction)

        Delamination

        • Are you printing hot enough? ABS suffers the most from poor layer adhesion. We have had good results printing ABS at 260C (no part cooling) with the Prometheus System.

        Jamming

        • Do you have your Prometheus V2 Hot End properly configured with a 2mm Transition-Zone as indicated in the assembly instructions?
        • Have you ensured that your part cooling fans are NOT blowing air over the nozzle tip?
        • Is the 25mm Heat Sink fan operating at full speed? Please ensure that this fan is always operating at 100% speed by wiring it directly to the 12V/24V output from your power supply.
        • Have you properly dried your filament overnight before printing with it? Extra moisture in the filament can lead to jamming.

        Stringing

        • Have you properly dried your filament overnight before printing with it? Extra moisture in the filament can lead to excessive stringing during filament switching which can cause jamming as the filament re-enters the hot end.
        • Are you using the most up-to-date filament switching G-code from the User Guide above?

        Purging

        • Are you printing hot enough? If your printing temperature is too low, it can result in increased extrusion pressure and melt flow viscosity which prevents effective purging during the filament switching process.
        • Are you using the most up-to-date filament switching G-code from the User Guide above?

        Switching

        • Are you using the most up-to-date filament switching G-code from the User Guide above?
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        CAD Drawings

        Prometheus V2 Hot End

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        ProFeeder

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        ProStruder

         

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