J-Head Mk 8

J-Head Mk 8
Brand: Reifsnyder Precision Works
Product Code: s-m8
Reward Points: 0
Availability: In Stock
Price: $56.99

Available Options

* Heater Cartridge Voltage:

* Orifice:

   - OR -   


The following is a list of just some of the improvements made to the J-Head Mk 8 over the Mk V-BV:

  • By using an axial thermistor, thermistor installation is easier and it will not fall out.
  • Heater cartridges are used so as to ease assembly.
  • There are now 2 internal seals.  Leaks are practically impossible.


This hot-end easily interfaces with the most popular RepRap extruders, including Wade's Extuder, Greg Frost's Hinged Accessible Extruder, etc.

Please note:  The maximum operating temperature is 247 degrees Celsius as PEEK will soften above 248 degrees Celsius.  Due to many variables, affecting the accuracy of the temperature readings and settings, caution is recommended when extruding at temperatures approaching this limit.

In the event that black PEEK is unavailable, tan PEEK may be substituted for the nozzle holder.

  • Internally, the filament path is identical to that of an already proven design.
  • The design is simple as the number of custom machined parts is kept to a minimum.
  • By using a one piece for a heater block, nozzle, and melt zone, leaking is practically impossible and heat transmission is greatly improved.
  • The PTFE is not stressed nor used to provide support. This reduces a point of failure that is part of other designs.
  • A heater cartridge is used to heat the melt zone.
  • Heat transmission is improved as there is no thermal junction where a separate heater screws onto the nozzle.
  • While recommended for PLA, a cooling fan is optional.


  • Assembled J Head MK 8 Hot-End.
  • Heater Cartridge
  • Honeywell Axial Thermistor, 100k (135-104QAD-J01 or similar)
  • PTFE Insulation for the thermistor
  • Hex key to tighten heater cartridge set screws.


  1. Insert the heater resistor into the proper hole and tighten the set screws by gently tightening the bottom set-screw first then tighten the top, hollow set-screw, against the bottom set-screw.
  2. After putting the ptfe insulation on the thermistor leads, Insert thermistor into thermistor hole such that the thermistor is centered inside the hot-end.  Bend the thermistor leads so as to keep the thermistor centered.
  3. Solder the heater cartridge leads and thermistor leads to appropriate wires/connectors as required by your electronics.
  4. See RepRap J Nozzle Wiki for attachment of assembled J-Head to extruder.

Links For More Information

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