J Head Nozzle

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Revision as of 20:49, 5 May 2011 by Reifsnyderb (talk | contribs) (Introduction)
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J-Head Nozzle

Release status: experimental

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Description
J-Head Nozzle and Thermal Barrier Based on a combination of ideas from the Makerbot Mk 5 hot end, The Inline Heater Variation, some ideas from Brian Briggs, as well as myself.
License
GPL
Author
Contributors
Based-on
Categories
CAD Models
External Link


Introduction

UNDER CONSTRUCTION

More information coming soon.

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 piece of PTFE tubing, as a liner, was requested 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 the "Inline Heater - Variation" on the Extruder Nozzle Variations page. 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 meet the goal to reduce the number of custom machined parts to a minimum.

Eliminating a separate heater block and any heater barrel altogether removes many machining operations, reduces the number of parts, and should reduce the cost.

Bill of materials

Quantity Part Description
1 Brass J-Head Nozzle Machined Brass Nozzle/Heater Combination
1 PEEK Insulator Machined PEEK Insulator
1 PTFE liner 1/8" ID, 1/4" OD PTFE tubing
1 Heater Resistor Axial, 5.6 ohm, 1%, 5W (UB5C-5.6-ND)
1 Support Washer Optional 1/2" Fender Washer

Machined parts

More information coming soon

J-Head Nozzle

Thermal Barrier

Machining

More information coming soon

J-Head Nozzle

  1. Find the center of the axis of the nozzle. This can be done by various means ranging from using a milling machine to using marking fluid, a height gauge, and a surface plate.
  2. Mount the 5/8" brass bar stock in a 4-jaw chuck on a lathe. Adjust the chuck so that the nozzle axis is on center.
  3. Turn the threaded end of the nozzle down to 0.375 +0.000 -0.004.
  4. Thread the nozzle to 3/8-24 up to the shoulder of the heater section.
  5. Drill out the center of the nozzle using a 6.5mm drill bit.
  6. Turn off the last 2 to 3 threads at the end of the nozzle and cleanup the threads.
  7. Remove the work piece and mount it by the threaded end so that the threaded end is centered in the lathe.
  8. Machine the nozzle tip to the desired profile.
  9. Drill the nozzle orifice.
  10. Mount the nozzle in a milling machine and mill off the excess material in the heater section.
  11. Drill out the holes for heater resistor and thermistor.

Thermal Barrier

  1. Cut a piece of PEEK to length.
  2. Drill out the PEEK to within ___ of the end using a 6.5mm drill bit.
  3. Using a letter size Q drill bit, enlarge the end to a depth of 0.525 +-0.010.
  4. Internally thread the end to 3/8-24 using a bottom tap.
  5. On the end, turn a 0.500 -0.000 +0.003 shoulder for a distance of approximately 0.050. This is an optional step to center the optional support washer.
  6. Reverse the PEEK thermal barrier in order to machine the opposite end.
  7. Using a 60 degree center drill, or other means, drill a tapered filament entrance in the end.
  8. Finish the thermal barrier by drilling out the end to 3.5mm.

Support Washer

The support washer is optional. It can be drilled out with M3 holes and M3 threaded rod can be used in order to provide additional support for the hot-end. If the support washer is not used, the PEEK thermal barrier can be secured in the extruder by using other means.

Assembly

Notes

  1. While this nozzle is experimental, initial tests have proven to be very positive. At this time, the prototype has printed for well over 20 hours.
  2. It may be possible to adapt this extruder to 1.75mm by replacing the PTFE tubing with a piece of 1/4" PTFE that has been drilled out to 1.75mm.


See also: Extruder Nozzle Variations