Diamond Hotend

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Crystal Clear action run.png
Diamond Hotend

Release status: working

Diamond Hotend Nozzle.jpg
triple filament hotend
See License section below
CAD Models
External Link

Diamond Hotend And Prints.jpg
Click image for credits

Compact multicolor printhead

Watch the video of the Prusa i3 Hephestos equipped with a Diamond Hotend printing the 3D-Hubs' mascot "Marvin" here


  • 3 pcs inputs for 1.7 mm filament
  • Common 0.4 mm nozzle orifice
  • Smallest possible mixing chamber for minimal waste and fast color change
  • Cutout for standard 40W heater cartridge and leaded thermistor
  • 3 pcs threaded mounting holes for state of the art E3D v6 HeatBreaks & HeatSinks
  • Combined mounting bracket and airguide for optimal cooling by a 50mm high efficiency fan
  • Optional pendant for attaching a 5015 blower fan for extrudate cooling
  • Weight of assembled hotend: 250 grams (nozzle, HeatSinks, cooling shield, fan, heater cartridge & thermistor)

The key feature of The Diamond Hotend is the diamond shaped nozzle. We have designed the nozzle to have smallest possible mixing chamber, to make color shifts as fast as possible and to avoid unnecessary filament waste. To ensure rapid nozzle heat up we have constructed the nozzle as compact as possible.
Diamond Hotend Nozzle.jpg

Benefits of this design

  • Easy calibration
  • Better precision compared to multi-nozzle printing
  • Prints with 3 different colors
  • Minimal filament waste

Diamond Hotend Closeup.jpg


These parts are recommended in order to construct a working Diamond hotend

Part list


  • 3 x PTFE Bowden tube (DO:4 mm / DI:2 mm /L:500 mm)
  • 3 x Bowden extruder (eg. MK9 bowden extruder)
  • 1 x Electronics capable of driving 6 stepper motors (eg. RUMBA)
  • 1 x Radial blower fan 5015S available from eBay in both a low and a high-power version (we found that the one with a label marked AV-5015S could deliver the most output)


Prusa i3 version

These instructions are written with Prusa i3 Hephestos in mind

  1. Diamond Hotend Step 1.png
    If you haven't already done so, or you want the one with the blower fan option, download and print out the Diamond Hotend Cooler Shield (http://www.thingiverse.com/thing:720520). For normal use we recommend printing the cooler shield in PLA. For printing with materials that require higher printing temperatures, we recommend printing the shield in ABS or another material with a higher glass transition temperature (Tg).

  2. Diamond Hotend Step 2A.JPGDiamond Hotend Step 2B.JPG
    Insert the two M3 nuts into the hexagonal holes at the rear of the printed Cooler Shield and press them into place. If necessary use a soldering iron to heat the nuts and melt them into place.
    The two holes are spaced 30.5 mm apart, hence it should fit most Prusa i3 printers, but check with your printer anyways - you may have to customize this part if your printer have different specifications.

  3. Diamond Hotend Step 3.JPG
    Apply a small amount of the thermal compound to the center hole of the Diamond Hotend.

  4. Diamond Hotend Step 4.JPG
    Insert the heater cartridge into the center hole of the Diamond Hotend and press it in as much as possible. Wipe off excess compound. If there's no excess remove the heater cartridge and repeat from step 3.

  5. Diamond Hotend Step 5A.JPGDiamond Hotend Step 5B.JPGDiamond Hotend Step 5C.JPGDiamond Hotend Step 5D.JPG
    Dip the thermistor tip into the remaining thermal compound and press it into the 2 mm hole in the Diamond Hotend along with some millimeters of the PTFE tubings, which will keep the thermistor locked in place.

  6. Diamond Hotend Step 6A.JPG
    Stack the three Thermal Isolator Sheets, feed the wire ends through their corresponding holes, then firmly press the sheets onto the Heat Breaks of the HeatSinks.

  7. Diamond Hotend Step 7.JPG
    Screw the HeatSinks loosely onto the Heat Breaks. Do not tighten yet, we will do this later.

  8. Diamond Hotend Step 8.JPG
    Grap the wire ends from the heater cartridge along with the thermistor wire ends and feed them all the way through the pointy end of the Cooler Shield orienting the shield in such a way that the thermistor is located closest to the Cooler Shield mounting plate. Press the small black Bowden Fittings in place.

  9. Diamond Hotend Step 9.JPG
    Making sure the wires remain in the central opening of the Cooler Shield, press the shield into the hotend assembly. The rear end of the HeatSinks must click equally into the grooves on the Cooler Shield. Retighten the HeatSinks but be careful not to over-tighten or the Heat Breaks might collapse.

  10. Diamond Hotend Step 10.JPG
    Use 3 cable ties to attach the HeatSinks onto the Cooler Shield and the fourth cable tie to attach the wires onto the rear part of the Cooler Shield (the side which has a groove where the cables will fit).

  11. Diamond Hotend Step 11.JPG
    Cut off any excess of the cable ties.

  12. Diamond Hotend Step 12.JPG
    Mount the fan using 4 pcs M3 x 20 mm countersunk screws. Make sure to orient the fan such that the airflow goes down into the Cooler Shield (label side of fan pointing into the assembly) and the wires coming out at the same side as the other wires.

  13. Diamond Hotend Step 13 Prusa i3.JPG
    Attach the hotend mount onto the carriage using 2 pcs M3 x 16 mm along with 2 pcs M3 washers.

  14. Diamond Hotend Rumba cut 12v.jpg
    To avoid filament clogging and/or meltdown of the Cooler Shield the fan must be constantly running. Be sure to connect it directly to 12 volt by cutting the heat shrinking tube into two pieces, sliding them over each wire (black and red) and soldering the bare leads onto the included extension cord. On a RUMBA board there is a 2 pin terminal referred to as 12V. Connect the black wire to - and the red wire to +.

  15. Diamond Hotend Rumba cut HE0.jpg
    Strip the outer 5 mm of the heater cartridge wire ends and mount them in the Hotend power output screw terminal. On a RUMBA board this is done via the terminal referred to as HE0. The thermistor plug goes to the pins marked T0.

  16. After heating up your Diamond Hotend the first time, you must carefully re-tighten the HeatSinks while hot. You may use a water pump size pliers but be extremely careful not to over-tighten. To avoid making marks or scratches on the HeatSinks you should put a piece of cloth in between.

  17. Done!
    Diamond Hotend Steps done 2.JPGDiamond Hotend Steps done 3.JPGDiamond Hotend Steps done 4.JPGDiamond Hotend Steps done 5.JPGDiamond Hotend Steps done 6.JPGDiamond Hotend Steps done 7.JPG
    Congratulations! You now have an assembled Diamond Hotend. You should now be ready for attaching 3 pcs 1.75 mm bowden extruders and the electronics.

Prusa i3 version with extrudate cooling

If you wish the benefits of actively cooling the extruded material while printing with your new Diamond Hotend (especially good for printing bridges and overhangs), we encourage you to browse to http://www.thingiverse.com/thing:720520. There you will find an alternate cooler shield file, this version features a pendant for attaching a 5015S radial blower fan.

  1. Download and print “diamond_cooler_shield_blower.stl”, and “bq_extruder_Tobera.stl”.
  2. Insert two M3 nuts into the cooler shield blower pendant.
  3. Screw the blower bracket in place using 2 pcs countersunk M3 x 10 mm screws.
  4. Screw the radial blower onto the blower bracket using 2 pcs M3 x 20 mm screws.
  5. Screw the blower nozzle onto the blower bracket using 1 pcs M3 x 15 mm screw.
  6. Extend the wires from the blower

Bowden tubes

You have to insert the Bowden tubes fully (approx. 53 mm) in all three E3D-(Lite6) HeatSinks before heating. If you do not, the HeatSinks will be get clogged - and after cooling the filament get stucked.

Firmware adaption

For the development of this hotend we have been using the RUMBA motherboard running Marlin

The necessary firmware adaptions listed below are centered on Marlin by Erik Zalm

In Configuration.h

#define MOTHERBOARD 80
#define EXTRUDERS 3
#define TEMP_SENSOR_0 6
#define TEMP_SENSOR_1 6
#define TEMP_SENSOR_2 6

In Pins.h (scroll down into the “RUMBA pin assignment” section)

#define TEMP_0_PIN 15
#define TEMP_1_PIN 15
#define TEMP_2_PIN 15

Electronics setup


If you are using a RUMBA motherboard to control your printer, here is how to set it up for the Diamond Hotend:

  1. Install the RUMBA TAURINO driver from RUMBA (scroll down to the RUMBA_USB_Driver_for_Windows section)
  2. Move the on-board jumper from Stand-alone to USB Power [2].
  3. Attach a MINI-USB cable.
  4. If you do not already have Arduino IDE installed on your computer, download and install it from http://arduino.cc/en/Main/Software. For general info on how to upload firmware onto the motherboard please see http://arduino.cc/en/Guide/HomePage.
  5. Using Arduino IDE, upload the Marlin (Stable) firmware to the motherboard. If you are using a different printer you might want to edit the firmware to fit your machine parameters.
  6. Move back the jumper to the Stand-alone position.
  7. Mount stepsticks into the sockets X, Y, Z E0, E1 and E2 on the Rumba motherboard. Caution: be sure to orientate them such that the corner pin marked EN is closer to the motor output terminals.
  8. Attach the thermistor to the T0 pin header.
  9. Power supply wires (12 volt) mounts in the MAIN-PWR screw terminal.

Note: if you are using the BLUE version of the Rumba board and want to connect a display via the EXP1 and EXP2 terminals, be aware that the silk print has those two connectors swapped, so you should connect the EXP1 cable to the terminal labeled EXP2 and vice-versa.


If your current electronics supports one or two extruders and has at least 6 GPIO pins in surplus you should be able to upgrade the number of extruders. Please see Adding more extruders.

Slicer settings


Print Settings tab:
Layers and perimeters → Layer height: 0.2 mm

Printer Settings tab:
General → Capabilities → Extruders: 3

Custom G-code → Start G-code:

M190 S[first_layer_bed_temperature]
M109 S[first_layer_temperature]
G0 Z5
G0 X0 Y0
G0 E8 F100
G0 E8 F100
G0 E8 F100
G0 X30 Z0 F1000
G0 Z0.1
G92 E0

Custom G-code → End G-code

M104 S0
M140 S0
G28 X0
G1 Z10 F1200

Extruder 1 → Size → Nozzle diameter: 0.4 mm
Extruder 1 → Position → Extruder offset: X: 0 mm
Extruder 1 → Position → Extruder offset: Y: 0 mm
Extruder 1 → Retraction → Length: 8 mm
Extruder 1 → Retraction → Lift Z: 0.1 mm
Extruder 1 → Retraction → Speed: 100 mm/s
Extruder 1 → Retraction → Extra length on restart: 0 mm
Extruder 1 → Retraction when tool is disabled → Length: 8 mm
Extruder 1 → Retraction when tool is disabled → Extra length on restart: 0.2 mm
(The same settings apply to extruder 2 & 3)

Alternative start code

This start gcode works very well with machines capable of fast Z-axis movements:

M190 S[first_layer_bed_temperature]  ; set bed temperature and wait until reached
M109 S[first_layer_temperature]
G28    ; home all axes
G91    ;Use relative coordinates
G0 Z3 E20 F100
G0 Y20 Z-3 F1000
G0 Z3 E20 F100
G0 Y20 Z-3 F1000
G0 Z3 E20 F100
G0 Y20 Z-3 F1000
G90     ;Use absolute coordinates
G92 E0


At the time of writing, triple-material slicing with Cura is not recommended. We tried, but the current version (v.15.01 at the time of writing) of Cura only works for dual material printing. However the developers of Cura has mentioned that this will become a feature from the next major version change.

Other slicing software

If you prefer using slicing software that has not been mentioned here and you have successfully applied workable settings, we encourage you to share these settings with the rest of the community by uploading them to one of the free online file sharing sites. Be sure to use the name Diamond Hotend either in the title, description or tags and add it to this section.

Multi-material printing with Repetier Host

  1. Diamond Hotend Printing Step 1.png
    Add your desired multi-material object (.amf file) using the encircled plus symbol on the right pane.

  2. Diamond Hotend Printing Step 2.png
    Again using the encircled plus symbol add “primetower.amf” then click the encircled areas and enter a Z-value to scale it in the Z-direction equal to the object in step 1.

  3. Diamond Hotend Printing Step 3.png
    Verify that the primetower is located behind the object to be printed as seen from View → Front View.

  4. Diamond Hotend Printing Step 4.png
    Choose Slic3r settings appropriate for the object you want to print and press “Slice with Slic3r...”.

  5. You can now print directly from within Reptier Host or choose to save your gcode to SD-card.

The primetower.amf file is accessible for download via the link mentioned in step 1 of the assembling instructions.

For further info on using Repetier Host please refer to the Repetier-Host Documentation: http://www.repetier.com/documentation/repetier-host/


The source code for the cooling shield is an OpenSCAD script that you can download here: thingiverse thing 720520
If you are making a Diamond Hotend mounting bracket for a different printer we encourage you to share your design with the rest of the community by uploading it to one of the free online file sharing sites. Please use the name Diamond Hotend either in the title, description or tags and add a link on this page.


The Diamond Nozzle is released under the Creative Commons CC-BY-NC-SA license. We chose this license because of the significant amount of man-hours invested in the project. The cooling shield and related parts that we have developed are released under the CC-BY-SA license. We intent to release the original project as a whole under the CC-BY-SA license, if and when we decide to publish a new or superior version of the project.

Revision History

Production batches: Rev. 0.1a (2 pcs produced for proof of concept)
Rev. 0.2b (10 pcs produced for beta testing)
Rev. 1.0

Fun facts

Beginning April 1st. a Kickstarter campaign were launched to initiate the production. A big thank you to everyone goes out to every one of the backers supporting this project by pedging in on the campaign. As of April 3rd. the campaign had reached its goal with still 27 days to go. At the end of the campaign the goal was met by over 400% of the original sum pledged (DKK150000).

How to get it

The Diamond Nozzle can be bought alone or as a Diamond Hotend kit at RepRap.me

Mounts for other printers