Prometheus V1.1 Assembly Instructions

Please read this entire document and follow ALL instructions carefully!
Assembly Time: < 30 minutes

Kit Components

Machined Parts:
  • 1x: 1-Piece Stainless Steel Nozzle (0.4mm orifice)
  • 1x: Aluminium Heater Block
  • 1x: Aluminium Heat Sink
    • 7x: Aluminium Hex Nut
    • 1x: Black Plastic Spacer (for Heat Sink)
    • 1x: 100mm PTFE Tubing (for Heat Sink)
    • 2x: M3x30mm Socket Head Cap Screw
    • 1x: M3x4mm Socket Head Cap Screw
    • 2x: M3 Hex Nut
    • 2x: M3 Washer
    • 1x: M2.5 Hex Wrench (for M3 Socket Screws)
    • 1x: 50x150mm Sheet of Aluminium Foil (for Resistor assembly)
      • 1x: 5.5x12mm 4.7Ohm Wirewound Resistor Heater (for 12V systems)
      • 1x: 100KOhm Semitec 104GT2 NTC thermistor
      • 1x: 12V 25x25x10mm 4CFM Cooling Fan (for Heat Sink)
      • 1x: Pair of Deans Connectors (for Resistor Wiring)
      • 1x: 50x170mm Sheet of Kapton Tape
      • 1x: Pair of 1000mm Thin (24AWG) Red and Black wires (for Thermistor Wiring)
      • 1x: Pair of 1000mm Thick (18AWG) Red and Black wires (for Resistor Wiring)

        Required Tools and Skills

        • Soldering Iron, Solder, and Basic Soldering Skills (Third-Hands are also very helpful)
        • Small Pliers (or ideally a very small Spanner)
        • 8mm Spanner
        • 12mm Spanner
        • Wire Strippers
        • Flush Cutters

          Safety Precautions (Important!)

          • Please follow ALL instructions in this document! If anything is unclear please contact me before trying something that may damage the product or harm the user.
          • Electricity can be dangerous! Ensure that your power is unplugged when you are hooking up the electronics.
          • Be careful with the 1-Piece SS Nozzles! While these Nozzles are quite strong, they do have a fairly thin wall of material. They will withstand all the normal stresses of operation, but please be careful when using heavy tools.
          • Be careful with the thermistors! The thermistor leads are very small and delicate and the bead is made of glass. To avoid shearing the thermistor leads or crushing the glass bead please handle this little thermistor like a newborn baby.
          • This “Hot End” gets pretty hot! Please do not touch the Heater Block while the hot end is in operation. It will hurt...

              Assembly Steps

              • You will receive two bags containing the kit components. Make sure you have everything:
              • "Melt-Zone" Length Assembly: The first step involves assembling the length of the "melt-zone". The "melt-zone" length is configured by threading aluminium hex nuts against the heat sink. Adding additional hex nuts increases the length of the "melt-zone". The "melt-zone" can be adjusted from about 12mm to 20mm in length. A shorter "melt-zone" results in more precise extrusion and retraction, and less "ooze" (stringing) at the expense of a lower maximum feed rate. A longer "melt-zone" results in a higher maximum feed rate at the expense of less precise extrusion and retraction, and more "ooze" (stringing). You may customize the "melt-zone" length according to your specific needs.
              • For beginners, I recommend a 14mm "melt-zone" for the 1.75mm hot end (use 2 additional hex nuts), and a 12mm "melt-zone" for the 3mm hot end (use 1 additional hex nut). You can always reassemble your hot end at a later time to change the "melt-zone" length so don't worry about this.
              • In the image below, I am assembling a 1.75mm hot end with a 14mm "melt-zone". Thread the Nozzle into the Heater Block and then thread 2 hex nuts against the Heater Block on the end of the Nozzle closest to the orifice:
              • While holding the heater block with a spanner, tighten each hex nut with another spanner. Individually tighten down each hex nut hard but be careful and make sure your hand doesn't slip!

              • "Transition-Zone" Length Assembly: Now we are going to set the length of the "transition-zone". For high performance and reliability, I recommend a very short 2mm to 3mm "transition-zone". This prevents jamming especially when printing with PLA. I am going to assemble a short "transition-zone length in these instructions.
              • Thread an additional hex nut onto the other end of the Nozzle until it is about 2mm to 3mm from the Heater Block:
              • Now thread the Heat Sink onto the nozzle until it touches the hex nut:
              • While holding the Heat Sink with a spanner, use pliers or (ideally) a very small spanner to tighten the hex nut against the Heat Sink hard. Be careful not to strip the hex nut if you are using pliers, and make sure your hand does not slip!
              • Installing the Cooling Fan: Insert the two M3x30mm Socket Screws into the two holes between the top two fins of the Heat Sink.
              • Thread these screws through the holes on the Cooling Fan so that the black sticker on the Cooling Fan faces the Heat Sink. It is important that you assemble the fan with the black sticker facing the Heat Sink to ensure that the fan will blow air through the Heat Sink. You may need to use the supplied M2.5 hex wrench to thread the screws through the Cooling Fan holes as it may be a tight fit.
              • Thread the two M3 Hex Nuts onto the ends of the screws and tighten them against the cooling fan using the supplied M2.5 hex wrench. This will secure the Cooling Fan against the Heat Sink: (NOTE: DO NOT use the M3 Washer at this point. It is necessary for the next assembly step)

              •  Now thread the small M3x4mm Socket Screw with an M3 Washer into the M3 threaded hole in the Heater Block. This will be used to secure the thermistor leads later in the assembly so don't tighten it down. There is an extra M3 washer in the kit in case you inhaled the first one.

              • Electronics Assembly: Remove the tape from the resistor leads.
              • Cut a 30mm strip of Kapton Tape:
              • Carefully wrap the Kapton Tape around the Resistor:

              • Try inserting the Resistor into the 5.5mm hole in the heater block and you will find that it is a little loose:
              • Cut an 18mm wide strip from the Aluminium Foil:
              • Carefully wrap the Aluminium Foil around the Resistor:
              • Try inserting the Resistor into the hole in the Heater Block: If it is too loose, cut another strip of Aluminium Foil, wrap it around the resistor, and try again. If it is too tight, cut a little off the aluminium foil and try again until you get a snug fit:


              • Cut a 10mm strip of Kapton Tape and then cut the strip in half:

              •  Wrap each piece of Kapton Tape around the Resistor leads close to the heater block. This will help secure the Aluminium Foil and prevent the Resistor from slipping out of the hole. 

              • Bend the Resistor leads at 90 degree angles. This will prevent the resistor from moving in the Heater Block: (Now is a good time to start heating up your Soldering Iron)
              • Take the Deans Connectors and fit them together as illustrated. This will ensure that we don't accidentally solder to the wrong connection:

              • Bend the Resistor leads as illustrated so that they can be soldered to the Deans Connectors:
              • Use a Third Hand or some sort of clips to hold the Resistor leads and Deans Connectors steady so that you will be able to solder the connection:
              • Solder the Resistor leads to the Deans Connectors:

              •  Take the thick red and black wires and use your wire strippers to remove about 5mm of the insulation sleeve. It is important that you use the thicker red and black wires supplied in the kit:

              • Use a Third Hand or some sort of clips to hold the Deans Connectors and the thick Red and Black wires steady so that you will be able to solder the connection:
              • Solder the Deans Connectors to the thick wires:

              • Cut two 20mm strips of Kapton Tape:
              • Wrap each strip of Kapton Tape around the soldered connections as illustrated:


              •  The hot end should now look like this:
              • Take the thin red and black wires and strip about 15mm of the insulation sleeve. Bend the wires into a loop as shown:

              • Take the little Semitec thermistor and (carefully!) spread the legs and bend the ends into loops:
              • Wrap the loops on the thermistor legs around the loops on the thin red and black wires and hold them steady so that you can solder the connections:
              • Solder the thermistor legs to the thin red and black wires:

              • Cut a 50mm strip of Kapton Tape and cut the corners off one side as shown:

              • Carefully wrap the thermistor leads in the piece of Kapton Tape. Make sure the leads are separated from each other and that the Kapton covers up to the bottom of the glass bead:

              • You may want to wrap an addition piece of kapton covering up to the bottom of the thermistor bead to ensure that the thermistor leads will not short to the Heater Block:

              • Carefully insert the bead of the thermistor into the thermistor hole at the top of the Heater Block closest to the Heat Sink and tighten the M3x4mm Socket Screw using the supplied M2.5 Hex Wrench. Make sure there is an M3 Washer between the head of the screw and the thermistor leads to avoid shearing the leads! Also, check that the glass thermistor bead is completely inserted into the hole before tightening to avoid crushing the bead. Please be careful!

              • Take the tie wrap from the Cooling Fan leads and use it to secure the Thermistor leads, Resistor leads, and Cooling Fan leads together to provide strain relief. Secure the leads past the Deans Connectors so that you will be able to easily disconnect the Deans Connectors if you want to disassemble the bottom half of the hot end to adjust the "melt-zone" length. Finally, bend the Resistor leads so that the Dean Connector is in front of the Cooling Fan. The airflow from the Cooling Fan will help cool the solder joints and prevent them from overheating:

              • Your nearly assembled hot end should look like this:
              • Standard Configuration: The following instructions are for assembling the Prometheus Hot End in Standard (NOT Bowden) Configuration. If you plan on using Prometheus in a bowden setup then skip the next few steps and you will see the instructions for Bowden Configuration.
              • Your kit included a small laser cut black acrylic Spacer (illustrated below). Inspect the spacer and you will see that the edges are slightly beveled. Insert the narrow end of the spacer into the top of the Heat Sink:


              • Take the 100mm long piece of PTFE tubing and cut a tiny bit off one end using your Flush Cutters to get a good flat edge. Insert the flat edge of the piece of tubing into the top of the Heat Sink:
              • Push the tubing all the way into the Heat Sink as far as it will go and then mark the top with a thin marker. This PTFE tubing will facilitate a smooth filament path from your extruder directly into the Nozzle, so make sure you have pushed the tubing all the way into the Heat Sink before marking it. You may have to use some force.
              • Take the tubing out of the Heat Sink and cut along the mark:
              • Once you have cut your piece of tubing, use an knife to bevel the inside edge of the top of the tubing. This is where the filament will enter the hot end so the bevel will allow for a smooth filament path from your extruder.
              • Now that the bottom of the tubing is cut straight and the inside edge of the top of the tubing is beveled, insert the tubing into the top of the Heat Sink with the beveled edge at the top of the Heat Sink:

              • Your hot end is fully assembled. You are now ready to hook it up to your electronics and configure your firmware. Proceed to the Electronics/Firmware Configuration steps below. Please DO NOT skip these steps!

              • Bowden Configuration: The following instructions are for assembling the Prometheus Hot End in Bowden (NOT Standard) Configuration. If you plan on using Prometheus in a Standard setup then scroll back up the page and you will see the instructions for Standard Configuration.
              • If you ordered a bowden coupler, you will receive a black coupler (for 1.75mm hot ends) or a beige coupler and black spacer (for 3mm hot ends). Thread the coupler into the top of the heat sink. If you are using a 3mm version, use the black spacer. See pictures below:
              • 1.75mm version:
              • 3mm version:
              • Now cut the end of your bowden tubing using your Flush Cutters to get a clean flat end. Push the tubing through the coupler as far as it will go. You may need to use some force.
              • 1.75mm version:
              • 3mm version:
              • To release the bowden tubing, simply push down on the black (1.75mm) or grey (3mm) collet while pulling on the tubing. Your hot end is now fully assembled. Proceed to the Electronics/Firmware Configuration steps below. Please DO NOT skip these steps!

              Electronics/Firmware Configuration

              • Wire the Cooling Fan directly to your 12V power supply, red wire = (+), black wire = (-). This will ensure that the fan runs continuously at full speed to provide optimal Heat Sink cooling. DO NOT connect the fan to your controller board "Fan" output as this output is used to control fans for cooling the printed part, NOT hot end fans that must always be running. Please ensure that this Cooling Fan is always on!
              • Wire the Resistor Heater and Thermistor to your controller board. This Heater MUST run on 12V!
              • Reconfigure your firmware for the Semitec 104-GT2 Thermistor: 
                • In Marlin this means using thermistor definition number 5#define TEMP_SENSOR_0 5
                • In Repetier Firmware use thermistor definition number 8#define EXT0_TEMPSENSOR_TYPE 8
                • In Smoothieware use thermistor definition “Semitec”temperature_control.hotend.thermistor Semitec
                • For RepRapFirmware use the Beta value 4267K.
              • Upload the new firmware to your electronics board.
              • Connect to your printer and run M303 PID Autotune. If your firmware does not support this feature, calibrate your PID manually.
              • Set the hot end to 280C. Using your pliers (or small spanners) check each hex nut to make sure they are all tight. If any of the Hex Nuts are loose, tighten them up. 
              • Mount Prometheus to your printer and start printing!


              CAD Drawings for the Prometheus V1.1 Hot End