This nozzle is a combination of ideas from other nozzle designs combined with a goal to reduce the number of custom machined parts to a bare minimum. By reducing the number of machined parts, it is hoped that the cost of this hot-end can be kept down while improving the reliability.The use of a machined piece of round PTFE, as a liner, was requested in one of two designs by Brian Briggs.

The idea of using the PTFE tubing as a liner, from the Cold End to the tip, was borrowed from the Makerbot Mk V extruder design. The PTFE tubing also acts to "bridge" the joint between the PEEK insulator and the brass nozzle/heater. By not having the filament in contact with this joint it is hoped that any possibility of leakage will be completely eliminated.

The use of a combination heater and nozzle was borrowed from ParCan's Inline Heater Nozzle Variation. However, instead of the heater resistor being mounted parallel to the path of the filament it is mounted perpendicular to the path of the filament. This was done to both reduce the length of the nozzle and to make it a little easier to run the leads from the heater resistor. Combining the heater and nozzle also helped to meet the goal to keep the number of custom machined parts to a minimum.

J-Head MKIV Hotend Advantages:

• 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.
• If necessary, the PTFE liner can be replaced by using an off-the-shelf piece of PTFE tubing.
• The PTFE is not stressed nor used to provide support. This reduces a point of failure that is part of other designs.
• A resistor is used as a heater. There is no need to wrap nichrome wire or to bake a heater core.
• Heat transmission is improved as there is no thermal junction where a separate heater screws onto the nozzle.
• With most versions weighing in at under 25 grams and the lightest version weighing in at under 13 grams, this design is very light.

Each MakerGeeks.com J-Head MKIV Hotend Includes:

• 1    J-Head Nozzle (v1.x)    Machined Brass Nozzle/Heater Combination, Version 1.x   
• 1    Nozzle Holder (v4)    Machined PEEK Nozzle Holder, Version 4   
• 1    PTFE liner (v1)    1/8" ID, 1/4" OD PTFE tubing, Version 1
• 1    Heater Resistor    Axial, 5.6 ohm, 1%, 5W    UB5C-5.6-ND
• 1    Thermistor 1    EPCOS 100K    B57560G104F
• 1    Hollow-lock socket set screw    5/16-24 hollow-lock socket set screw