J Head Nozzle

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J-Head Nozzle

Release status: working

Jhn mk4 b.jpg
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, and some ideas from me.
License
GPL
Author
Contributors
Based-on
Categories
CAD Models
External Link


Introduction

Jhn mk4 b.jpg

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.

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, this design is very light.

Disadvantages

  • Considerable machining is required.

Suppliers

Parts List

Mk I

Jhn mk1.jpg

Quantity Part Description Part Number
1 J-Head Nozzle (v1) Machined Brass Nozzle/Heater Combination, Version 1
1 Nozzle Holder (v1) Machined PEEK Nozzle Holder, Version 1
1 PTFE liner 1/8" ID, 1/4" OD PTFE tubing McMaster-Carr 5033K31
1 Heater Resistor Axial, 5.6 ohm, 1%, 5W UB5C-5.6-ND
1 Thermistor 100K B57560G104F
1 Support Washer Optional 1/2" Fender Washer McMaster-Carr 91090A114

Mk II

Jhn mk2.jpg

Quantity Part Description Part Number
1 J-Head Nozzle (v1) Machined Brass Nozzle/Heater Combination, Version 1
1 Nozzle Holder (v2) Machined PEEK Nozzle Holder, Version 2
1 PTFE liner 1/8" ID, 1/4" OD PTFE tubing McMaster-Carr 5033K31
1 Heater Resistor Axial, 5.6 ohm, 1%, 5W UB5C-5.6-ND
1 Thermistor 100K B57560G104F
1 Hollow-lock socket set screw 5/16-24 hollow-lock socket set screw McMaster-Carr 91301A150
1 Support Washer Optional 1/2" Fender Washer McMaster-Carr 91090A114

Mk III

Jhn mk3.jpg

Quantity Part Description Part Number
1 J-Head Nozzle (v2) Machined Aluminum Nozzle/Heater Combination, Version
1 Nozzle Holder (v3) Machined PEEK Nozzle Holder, Version 3
1 Heat Sink Machined Aluminum Heat Sink
1 PTFE liner 1/8" ID, 1/4" OD PTFE tubing McMaster-Carr 5033K31
1 Heater Resistor Axial, 5.6 ohm, 1%, 5W UB5C-5.6-ND
1 Thermistor 100K B57560G104F
1 Hollow-lock socket set screw 5/16-24 hollow-lock socket set screw McMaster-Carr 91301A150
1 Support Washer Optional 1/2" Fender Washer McMaster-Carr 91090A114

Mk III-B

Jhn mk3 b pic.jpg

Quantity Part Description Part Number
1 J-Head Nozzle (v1) Machined Brass Nozzle/Heater Combination, Version 1
1 Nozzle Holder (v3) Machined PEEK Nozzle Holder, Version 3
1 Heat Sink Machined Aluminum Heat Sink
1 PTFE liner 1/8" ID, 1/4" OD PTFE tubing McMaster-Carr 5033K31
1 Heater Resistor Axial, 5.6 ohm, 1%, 5W UB5C-5.6-ND
1 Thermistor 100K B57560G104F
1 Hollow-lock socket set screw 5/16-24 hollow-lock socket set screw McMaster-Carr 91301A150
1 Support Washer Optional 1/2" Fender Washer McMaster-Carr 91090A114

Mk IV

Quantity Part Description Part Number
1 J-Head Nozzle (v2) Machined Aluminum Nozzle/Heater Combination, Version 2
1 Nozzle Holder (v4) Machined PEEK Nozzle Holder, Version 4
1 PTFE liner 1/8" ID, 1/4" OD PTFE tubing McMaster-Carr 5033K31
1 Heater Resistor Axial, 5.6 ohm, 1%, 5W UB5C-5.6-ND
1 Thermistor 100K B57560G104F
1 Hollow-lock socket set screw 5/16-24 hollow-lock socket set screw McMaster-Carr 91301A150
1 Support Washer Optional 1/2" Fender Washer McMaster-Carr 91090A114

Mk IV-B

Jhn mk4 b.jpg

Quantity Part Description Part Number
1 J-Head Nozzle (v1) Machined Brass Nozzle/Heater Combination, Version 1
1 Nozzle Holder (v4) Machined PEEK Nozzle Holder, Version 4
1 PTFE liner 1/8" ID, 1/4" OD PTFE tubing McMaster-Carr 5033K31
1 Heater Resistor Axial, 5.6 ohm, 1%, 5W UB5C-5.6-ND
1 Thermistor 100K B57560G104F
1 Hollow-lock socket set screw 5/16-24 hollow-lock socket set screw McMaster-Carr 91301A150
1 Support Washer Optional 1/2" Fender Washer McMaster-Carr 91090A114

Mk V

(Experimental and Subject To Change)

Jhn mk5.jpg

Quantity Part Description Part Number
1 J-Head Nozzle (v5) Machined Brass Nozzle/Heater Combination, Version 5
1 Nozzle Holder (v5) Machined PEEK Nozzle Holder, Version 5
1 PTFE liner 1/8" ID, 1/4" OD PTFE tubing McMaster-Carr 5033K31
1 Heater Resistor Axial, 5.6 ohm, 1%, 5W UB5C-5.6-ND
1 Thermistor 100K B57560G104F
1 Hollow-lock socket set screw 5/16-24 hollow-lock socket set screw McMaster-Carr 91301A150
1 Support Washer Optional 1/2" Fender Washer McMaster-Carr 91090A114

Parts Descriptions

Machined Parts

J-Head Nozzle

Jhn machining.jpg


Version 1

Jhn nozzle ver1.jpg

Jhn md brass heater nozzle.jpg

Material: Brass Bar Stock, 5/8" Square Or 5/8" x 1/2" Rectangular, 1.125" Long

Finished Weight: 11.1 grams (14.4 grams w/optional improvements)

Note: These instructions differ from the machining example displayed in the above picture and are only one example of how the nozzle can be machined. The machining process can vary depending upon available machinery and tooling. The minimum machining requirements are a metal lathe with a 4-jaw independent chuck.

  1. Cut a piece of brass bar stock 1.125" long plus enough to adequately hold the stock in the lathe.
  2. On the brass bar stock, 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.
  3. Mount the brass bar stock in a 4-jaw chuck on a lathe. Adjust the chuck so that the nozzle axis is on center.
  4. Turn the threaded end of the nozzle down to 0.375 +0.000 -0.004.
  5. Thread the nozzle to 3/8-24 up to the shoulder of the heater section.
  6. Drill out the center of the nozzle using a 6.5mm drill bit.
  7. Turn off the last 3 threads, at the end of the nozzle, and cleanup the threads.
  8. Cut a 30 degree taper on the very end of the threaded end of the brass nozzle. This is to completely eliminate the internal gap between the brass nozzle and the PEEK thermal barrier. This gap would exist due to the internal taper created by the cutting edge of the drill bit.
  9. Remove the work piece and mount it by the threaded end so that the threaded end is centered in the lathe.
  10. Cut-off any excess material.
  11. Machine the nozzle tip to the desired profile.
  12. Drill the nozzle orifice.
  13. Mill or turn off the excess material in the heater section. This can be accomplished by mounting the nozzle in the 4-jaw chuck sideways so that the excess material is presented for machining. If available, a milling machine can also be used. (If a 5/8" x 1/2" piece of bar stock is used, this step will be skipped.)
  14. Using a letter size A drill bit, drill out the hole for the heater resistor.
  15. Drill out the hole for the thermistor.


Optional Improvements:

  1. Melt Chamber: Drill out the internal cavity to a depth of 0.560 with the 6.5mm drill bit. Finish drilling the internal cavity with a 3.5mm drill bit.
  2. Nozzle Orifice Spout Diameter: Reduce the diameter of the nozzle orifice spout from 0.080 to 0.050. This will reduce the size of the tip that can catch on the print.
  3. Start of Nozzle Orifice Taper: Start the taper at 0.050 from the heater block section. This will add room for optional insulation.
Version 2

Jhn nozzle ver2.jpg

Material: Aluminum Bar Stock, 5/8" Square Or 5/8" x 1/2" Rectangular, 1.125" Long

Finished Weight: 3.8 grams

Note: The primary reason for using aluminum is to save weight. The alloy should be 2024, 7075, or a similar harder, high quality, alloy. Softer alloys, such as 6061, are not recommended.

The blueprint and instructions are identical to Version 1 of the J-Head Nozzle.

Version 3

Material: Aluminum (2024 or 7075) Bar Stock, 1/2" Square, 1.000" Long

Finished Weight: Unknown

(Instructions are incomplete at this time.)

  1. Cut a piece of aluminum bar stock 1.000" long plus enough to adequately hold the stock in the lathe.
  2. On the aluminum bar stock, 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.
  3. Mount the brass bar stock in a 4-jaw chuck on a lathe. Adjust the chuck so that the nozzle axis is on center.
  4. Turn the threaded end of the nozzle down to 0.375 +0.000 -0.004. The threaded end will be 0.500" long.
  5. Thread the nozzle to 3/8-24 up to the shoulder of the heater section.
  6. Drill out the center of the nozzle, to a depth of 0.500", using a 6.5mm drill bit. The depth will be measured from the side of the hole.
  7. Drill out the center of the nozzle, to a depth of ____, using a 3.5mm drill bit.
  8. Turn off the last 3 threads, at the end of the nozzle, and cleanup the threads.
  9. Cut a 30 degree taper on the very end of the threaded end of the brass nozzle. This is to completely eliminate the internal gap between the brass nozzle and the PEEK thermal barrier. This gap would exist due to the internal taper created by the cutting edge of the drill bit.
  10. Remove the work piece and mount it by the threaded end so that the threaded end is centered in the lathe.
  11. Cut-off any excess material.
  12. Machine the nozzle tip to the desired profile.
  13. Drill the nozzle orifice.
  14. Using a _______ drill bit, drill out the hole for the heater resistor.
  15. Drill out the hole for the thermistor.
Version 4

(Short Experimental Version)

Material: Brass Bar Stock, 5/8" Square Or 5/8" x 1/2" Rectangular, 1.000" Long

Finished Weight: 13.8 grams

  1. Cut a piece of brass bar stock 1 inch long plus enough to adequately hold the stock in the lathe.
  2. On the brass bar stock, 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.
  3. Mount the brass bar stock in a 4-jaw chuck on a lathe. Adjust the chuck so that the nozzle axis is on center.
  4. Turn the threaded end of the nozzle down to 0.375 +0.000 -0.004. This section is 0.400 +-0.005 long.
  5. Thread the nozzle to 3/8-24 up to the shoulder of the heater section.
  6. Drill out the center of the nozzle, to a depth of 0.400 +-0.005, using a 6.5mm drill bit.
  7. Drill out the heat chamber using a 3.5mm drill bit.
  8. Remove the work piece and mount it by the threaded end so that the threaded end is centered in the lathe.
  9. Cut-off any excess material.
  10. Machine the nozzle tip to the desired profile.
  11. Drill the nozzle orifice.
  12. Using a size A drill bit, drill the heater resistor hole through the heater block section.

Nozzle Holder

Note: PEEK nozzle holders have a maximum working temperature of roughly 248 degrees Celsius. Due to many variables, it is highly recommended that this temperature is not to be approached. Above this temperature, PEEK will melt and the hot-end will fail.


Version 1

Jhn thermal barrier.jpg

Note: Picture shown displays the 36.5mm nozzle holder without optional mounting groove.

Jhn nozzle holder v1.jpg

Material: PEEK, 5/8" Round, 36.5mm Long Or 50mm Long

Note: The length can be increased, if necessary. (i.e. Increase the length to 50mm for the Sells Mendel and/or if the heat-sink is going to be installed.) All dimensions on the hot-end side, of the thermal barrier, would remain the same.

  1. Cut a piece of 5/8" round PEEK to length.
  2. Drill out the PEEK using a 6.5mm drill bit.
  3. Using a letter size Q drill bit, enlarge one end to a depth of 0.450 +-0.005.
  4. Internally thread the end to 3/8-24 using a bottom tap.
  5. (Optional) Turn a 0.500 -0.000 +0.005 shoulder for a distance of approximately 0.050. (This will keep the support washer centered and insulated from the brass nozzle.)
  6. (Optional) 4.76mm from the cold-end, turn a groove that is 4.64mm wide with an OD of 12mm.
Version 2

Jhn nozzle holder v2 pic.jpg

Note: Picture shown displays the 50mm nozzle holder with the optional mounting groove. Not shown is the opposite end, which is threaded for the hollow-lock socket set screw.

Jhn nozzle holder v2.jpg

Material: PEEK, 5/8" Round, 36.5mm Long Or 50mm Long

Finished Weight: 9.6 grams (50mm, with mounting groove)

Note: The length can be increased, if necessary. (i.e. Increase the length to 50mm for the Sells Mendel and/or if the heat-sink is going to be installed.) All dimensions on the hot-end side, of the thermal barrier, would remain the same.

  1. Cut a piece of 5/8" round PEEK to length.
  2. Drill out the PEEK using a 6.5mm drill bit.
  3. Using a letter size Q drill bit, enlarge one end to a depth of 0.450 +-0.005.
  4. Internally thread the end to 3/8-24 using a bottom tap.
  5. (Optional) Turn a 0.500 -0.000 +0.005 shoulder for a distance of approximately 0.050. (This will keep the support washer centered and insulated from the brass nozzle.)
  6. Using a letter size I drill bit, drill out the cold end for a distance of 0.200.
  7. Internally thread the cold end to 5/16-24. (A special bottom tap has to be ground in order to finish threading this hole. This tap will not have any incomplete threads.)
  8. (Optional) 4.76mm from the cold-end, turn a groove that is 4.64mm wide with an OD of 12mm.
Version 3

Jhn nozzle holder v3 pic.jpg

Jhn nozzle holder v3.jpg

Material: PEEK, 5/8" Round, 50mm Long

Finished Weight: 8.6 grams (50mm, with mounting groove)

  1. Cut a piece of 5/8" round PEEK to length.
  2. Drill out the PEEK using a 6.5mm drill bit.
  3. Using a letter size Q drill bit, enlarge one end to a depth of 0.450 +-0.005.
  4. Internally thread the end to 3/8-24 using a bottom tap.
  5. (Optional) Turn a 0.500 -0.000 +0.005 shoulder for a distance of approximately 0.050. (This will keep the support washer centered and insulated from the brass nozzle.)
  6. Using a letter size I drill bit, drill out the cold end for a distance of 0.200.
  7. Internally thread the cold end to 5/16-24. (A special bottom tap has to be ground in order to finish threading this hole. This tap will not have any incomplete threads.)
  8. (Optional) 4.76mm from the cold-end, turn a groove that is 4.64mm wide with an OD of 12mm.
  9. Using a 3/8" drill bit, drill heat-sink hole 0.787 -0.000 +0.040 from the hot-end.
Version 4

Jhn nozzle holder v4 pic.jpg

Jhn nozzle holder v4.jpg

Material: PEEK, 5/8" Round, 36.5mm or 50mm Long

Finished Weight: 7.5 grams (50mm, w/mounting groove)

  1. Start with a completed version 2 nozzle holder.
  2. Optional: At the hot end of the nozzle holder, mill two flats opposite of each-other for using a 1/2" (13mm) open end wrench. Each flat will be 0.250 (6.5mm) wide and 0.250 (6.5mm) from the axis of the nozzle holder.
  3. Mount the nozzle holder in an indexer on a milling machine.
  4. Equip the milling machine with a 2mm or 3/32 ball end mill. (The dimensions of the ball end mill do not have to be very precise.)
  5. Start the first groove so that it's edge is 0.600" from the hot-end of the nozzle holder.
  6. Mill 3 grooves (36.5mm version) or 5 grooves (50mm version) as follows. The grooves will be interrupted for the supports.
    1. Each groove is 0.150" deep.
    2. The centers, of each groove, are 0.125" apart.
    3. Each groove has an angular cut of 90 degrees and is milled between the following angles: 0-90, 120-210, 240-330
    4. Each groove support is drilled out at the following angles with the center, of it's support, at 90 degrees to the end mill: 15, 135, 255
    5. To drill out each groove support, the end-mill is positioned so that it's edge, towards the center of the nozzle holder, is 0.150" from the outer edge of the nozzle holder.
Version 5

Material: PEEK, 5/8" Round, 36.5mm Long

Finished Weight: < 5.2 grams

  1. Start with a completed version 2 nozzle holder.
  2. Optional: At the hot end of the nozzle holder, mill two flats opposite of each-other for using a 1/2" (13mm) open end wrench. Each flat will be 0.250 (6.5mm) wide and 0.250 (6.5mm) from the axis of the nozzle holder.
  3. Mount the nozzle holder in an indexer on a milling machine.
  4. Equip the milling machine with a 2mm or 3/32 ball end mill. (The dimensions of the ball end mill do not have to be very precise.)
  5. Start the partial groove so that it's edge is 0.325" from the hot-end of the nozzle holder.
  6. Mill this groove as follows. The groove is interrupted in order to strengthen the nozzle holder.
    1. Each section, of this groove, is 0.0850" deep.
    2. This groove has an angular cut of 90 degrees and is milled between the following angles: 0-90, 120-210, 240-330
  7. Start the first full groove so that it's edge is 0.450" from the hot-end of the nozzle holder.
  8. Mill 3 grooves as follows. The grooves will be interrupted for the supports.
    1. Each groove is 0.150" deep.
    2. The centers, of each groove, are 0.125" apart.
    3. Each groove has an angular cut of 90 degrees and is milled between the following angles: 0-90, 120-210, 240-330
    4. Each groove support is drilled out at the following angles with the center, of it's support, at 90 degrees to the end mill: 15, 135, 255
    5. To drill out each groove support, the end-mill is positioned so that it's edge, towards the center of the nozzle holder, is 0.150" from the outer edge of the nozzle holder.
Experimental, Fluted

Jhn nozzle holder fluted.gif

Material: PEEK, 5/8" Round, 50mm Long

Finished Weight: 5.5 grams

Note: This nozzle holder is turned down and fluted in order to reduce the weight.

  1. Start with a completed version 2 nozzle holder.
  2. From the hot-end, turn the first 0.600 down to 0.550.
  3. Turn the section to be fluted down to 12mm.
  4. Mount the nozzle holder in an indexer on a milling machine.
  5. Using a 2mm ball end-mill, cut 12 flutes along the length of the center section. Each flute will be cut about 0.070 deep and will be cut at 30 degree intervals.

Heat Sink

Jhn heat sink.JPG

Jhn heat sink.jpg

Jhn heat sink installed.jpg Jhn heat sink internal view.jpg

Material: Aluminum, 3/8" Round, 1.160" Long

Finished Weight: 3.6 grams

Note: This item is an optional addition and helps considerably when printing with PLA.

  1. Cut a piece of 3/8" round aluminum to length.
  2. Using a 1mm (0.040) cutoff tool, make 3 grooves in each end. The grooves will be 0.050 deep and 1mm apart.
  3. Using a 6.5mm drill bit, cross-drill the heat-sink to create the PTFE liner passage. This hole is to be centered in both directions.
  4. (Optional) Drill out each end for 0.350 with a number 25 drill bit. These holes are to lighten the heat sink.

Modifying the Nozzle Holder:

Note: Due to there being slightly less than 12mm clearance with a 36.5mm nozzle holder, between the cold-end of the nozzle holder and the heat sink, using a 50mm nozzle holder is advisable. (Different thermal barrier lengths are shown in the above pictures.)

  1. If it is desirable to orient the heat sink in a certain direction relative to the brass nozzle, install the brass nozzle.
  2. Using a 3/8" drill bit, cross-drill the nozzle holder so that the center of the hole is 0.787 -0.000 +0.040 from the hot end.

1.75mm Conversion

Two machined parts are required in order to convert a post Mk I J-Head hot-end to use 1.75mm filament. They are the PEEK hollow set screw and the 1.75mm PTFE liner.

PEEK hollow set screw

More information coming soon...

1.75mm PTFE Liner

More information coming soon...

Off-The-Shelf Parts

Heater Resistor

5.6 ohm (Large Standard)

Jhn heater resistor 5 6.jpg

Description: Axial, 5.6 ohm, 1%, 5W

Part Number: UB5C-5.6-ND

Weight: 1.6 grams

Note: If this resistor is unavailable, the 6.8 ohm (Large Alternate) resistor can be used.

6.8 ohm (Large Alternate)

Description: Axial, 6.8 ohm, 5%, 3W

Part Number: W21-6R8JI

Note: The outside diameter tolerance, of this resistor, is very loose. Because of this, the resistor will usually fit loosely in the hole. In order to install this resistor, fire cement or muffler putty is almost mandatory.

6.8 ohm (Small)

Description: Axial, 6.8 ohm, 5%, 3W

Part Number: RWMA-6.8CT-ND

Weight: 1.1 grams

PTFE Liner

Jhn ptfe liner.jpg

Material: PTFE tubing, 0.250" OD, 0.125" ID

  1. Using a razor knife, cut the tubing to desired length. The length is dependent upon the length of the nozzle holder used.
  2. Cut an approximately 30 degree (or greater) taper on what will be the hot-end of the PTFE liner.
  3. Optional: An internal taper can be made, on the cold end, by chucking the liner in a lathe and using a center drill. This taper improves the initial feeding of the filament into the hot-end.

Note: The prototype nozzle has worked without this taper. However, the taper would not have to be too precise as PTFE is quite flexible. If a lathe is not available, it may be possible to cut a workable taper with a pencil sharpener.

Support Washer

Jhn support washer.jpg

The support washer is optional. It can be drilled out with 3mm 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 nozzle holder can be secured in the extruder by using other means.


Thermistor

Jhn thermistor.jpg

Part Number: B57560G104F

Manufacturer: EPCOS

Description: NTC thermistor sealed in glass body

Data Sheet: NTC Thermistors For Temperature Measurement

Diameter of Glass Bead: 2.3mm +-0.2mm

Length of Glass Bead: 4.1mm +-0.5mm

Lead Length: 67mm +-0.5mm

Lead Diameter: 0.3mm


Recommended Beta: 4066

If using Sprinter firmware, select temperature table #1.


#define NUMTEMPS 61 short temptable[][2] = { { 23 , 300 }, { 25 , 295 }, { 27 , 290 }, { 28 , 285 }, { 31 , 280 }, { 33 , 275 }, { 35 , 270 }, { 38 , 265 }, { 41 , 260 }, { 44 , 255 }, { 48 , 250 }, { 52 , 245 }, { 56 , 240 }, { 61 , 235 }, { 66 , 230 }, { 71 , 225 }, { 78 , 220 }, { 84 , 215 }, { 92 , 210 }, { 100 , 205 }, { 109 , 200 }, { 120 , 195 }, { 131 , 190 }, { 143 , 185 }, { 156 , 180 }, { 171 , 175 }, { 187 , 170 }, { 205 , 165 }, { 224 , 160 }, { 245 , 155 }, { 268 , 150 }, { 293 , 145 }, { 320 , 140 }, { 348 , 135 }, { 379 , 130 }, { 411 , 125 }, { 445 , 120 }, { 480 , 115 }, { 516 , 110 }, { 553 , 105 }, { 591 , 100 }, { 628 , 95 }, { 665 , 90 }, { 702 , 85 }, { 737 , 80 }, { 770 , 75 }, { 801 , 70 }, { 830 , 65 }, { 857 , 60 }, { 881 , 55 }, { 903 , 50 }, { 922 , 45 }, { 939 , 40 }, { 954 , 35 }, { 966 , 30 }, { 977 , 25 }, { 985 , 20 }, { 993 , 15 }, { 999 , 10 }, { 1004 , 5 }, { 1008 , 0 } };

Thermocouple

Assembly

Mk I

Jhn assembly.jpg Jhn assembled w washer.jpg


  1. Secure the brass nozzle in a vise by the heater section.
  2. Optionally, install the support washer. If the support washer is to be used, drill the appropriate holes for the support rods prior to installation. (Note: The above pictures do not have holes drilled as it is possible that the hole locations could vary.)
  3. Screw the nozzle holder down into the nozzle. If necessary, use a pair of pliers to tighten the nozzle. The nozzle holder can be protected from the pliers by first wrapping it with a rag or paper towel.
  4. Using a dental pick, straightened out paper clip, small screw driver, etc., ensure that the nozzle holder is screwed down all the way by feeling for an internal gap between the brass and the nozzle holder. If a gap can be felt, screw the nozzle holder even tighter. If there is a gap, the PTFE liner can "flow" into the gap and eventually cause the print head to fail.
  5. Slide the PTFE liner down into the thermal barrier. The liner must be inserted by the tapered end and it is important that the tapered end is in contact with the inside of the tip of the nozzle.
  6. Cut the top end of the PTFE liner with a razor knife. It should project out of the nozzle holder slightly to ensure that the extruder keeps the PTFE liner from backing out.

Mk II

  1. Secure the brass nozzle in a vise by the heater section.
  2. Optional: Install the support washer. If the support washer is to be used, drill the appropriate holes for the support rods prior to installation. (Note: The above pictures do not have holes drilled as it is possible that the hole locations could vary.)
  3. Screw the nozzle holder down onto the nozzle. If no flats are milled, use a pair of pliers to tighten the nozzle. The nozzle holder can be protected from the pliers by first wrapping it with a rag or paper towel. If there are flats milled, a 13mm (1/2") open-end wrench can be used to tighten the nozzle.
  4. Using a dental pick, straightened out paper clip, small screw driver, etc., ensure that the nozzle holder is screwed down all the way by feeling for an internal gap between the brass and the nozzle holder. If a gap can be felt, screw the nozzle holder even tighter. If there is a gap, the PTFE liner can "flow" into the gap and eventually cause the print head to fail.
  5. Slide the PTFE liner down into the nozzle holder. The liner must be inserted by the tapered end and it is important that the tapered end is in contact with the inside of the tip of the nozzle.
    1. If the optional melt chamber has been added, to the nozzle, the PTFE will not make contact with the tip. Instead, it will make contact with the top edge of the melt chamber.
    2. If the PTFE liner doesn't seem to be seating properly, it may be because the PTFE liner is getting hung up on the inside edge of the brass nozzle. Follow the following directions:
      1. Unscrew the brass nozzle from the PEEK nozzle holder.
      2. Install the PTFE liner so that about 1/2 of it is sticking out the hot end of the PEEK nozzle holder.
      3. Screw the PEEK nozzle holder onto the brass nozzle. The PTFE liner will be pushed back as you push and screw the assembly together.
      4. You may need to follow this sub-set of directions after you have marked and cut the PTFE liner to the correct length.
  6. With a razor knife, mark the PTFE liner where it is flush with the top of the nozzle holder.
  7. Remove the PTFE liner.
  8. From the mark, use a razor knife to cut the PTFE liner about 5/32" towards the tapered end.
  9. Optional: Chuck the liner in a lathe and face-off the cold end of the liner. Then, using a center drill, make a slight internal taper in the end of the liner.
  10. Slide the PTFE liner back down into the thermal barrier.
  11. Screw in the hollow-lock socket set screw. It will need to be lightly tightened. Over-tightening may result in the PTFE liner becoming distorted.

Mk III

  1. Install the heat-sink. The heat-sink will probably need to be pressed in place. Care must be taken to ensure that the heat-sink liner passage is properly aligned with the nozzle holder liner passage. After the heat-sink is installed, ensure that the liner passage is clear of any debris.
  2. Secure the aluminum nozzle in a vise by the heater section.
  3. Optionally, install the support washer. If the support washer is to be used, drill the appropriate holes for the support rods prior to installation. (Note: The above pictures do not have holes drilled as it is possible that the hole locations could vary.)
  4. Screw the nozzle holder down onto the nozzle. If necessary, use a pair of pliers to tighten the nozzle. The nozzle holder can be protected from the pliers by first wrapping it with a rag or paper towel.
  5. Using a dental pick, straightened out paper clip, small screw driver, etc., ensure that the nozzle holder is screwed down all the way by feeling for an internal gap between the brass and the nozzle holder. If a gap can be felt, screw the nozzle holder even tighter. If there is a gap, the PTFE liner can "flow" into the gap and eventually cause the print head to fail.
  6. Slide the PTFE liner down into the nozzle holder. The liner must be inserted by the tapered end and it is important that the tapered end is in contact with the inside of the tip of the nozzle.
  7. With a razor knife, mark the PTFE liner where it is flush with the top of the nozzle holder.
  8. Remove the PTFE liner.
  9. From the mark, use a razor knife to cut the PTFE liner about 5/32" towards the tapered end.
  10. Slide the PTFE liner back down into the thermal barrier.
  11. Screw in the hollow-lock socket set screw. It will need to be lightly tightened. Over-tightening may result in the PTFE liner becoming distorted.

Mk IV

The assembly instructions are identical to those of the Mk II.


Mk V

The assembly instructions are identical to those of the Mk II.


Heater Resistor

The heater resistor can be installed one of 3 ways:

  1. Put a little bit of muffler repair putty on the resistor and slide it into the hole. It can be cured by letting it set a couple hours before bringing the hot-end up to temperature.
  2. Slide the heater resistor in the hole. If it fits tightly, this will work. If there is any gap, between the resistor and brass, it may result in failure of the heater resistor.
  3. Wrap a thin strip of aluminum foil around the heater resistor and adjust it by gradually cutting it shorter until the resistor and file slide it into. Care must be taken to ensure that the proper amount of aluminum foil is used in order to take up any gap between the heater resistor and the brass.

Thermistor

Note: The thermistor table is here.

  1. Insulate the leads to the thermistor. This is usually accomplished one of two ways.
    1. Use Kapton tape as insulation by separating the leads and sandwiching the leads in between two strips of kapton tape.
    2. Use PTFE insulation and slide it over each lead.
  2. Place the thermistor in it's hole and secure it with Kapton tape.

Installation

Using the Mounting Holes in the Wade Extruder

Wade Extruder

  1. Insert the nozzle holder in the 5/8 inch (16mm) hot-end socket.
  2. Using a sharp instrument or other object, mark the 4 hole locations on the nozzle holder.
  3. Remove the nozzle holder.
  4. Using a round file, file the mounting grooves in the nozzle holder in order to create 2 grooves for the mounting screws or bolts to pass through.
  5. Install the hot end.


Using The Support Washer

  1. Prior to installing the optional support washer, mark and drill the appropriate mounting holes on the support washer.
  2. Install the optional support washer in between the J-Head Nozzle and the nozzle holder.
  3. Use the support rods, screws, and/or washers to hold the hot-end in place.


Using Wire With The Support Washer

Example

  1. Cut 4 evenly-spaced slots in the support washer.
  2. Run the wire into the channels.
  3. Tighten the wire vertically and diagonally. Then wrap wire around the middle tightly, tightening all of the vertical and diagonal runs.


Using A Mounting Groove

Use a nozzle holder that is machined with the optional mounting groove and a cold-end that is designed for using a mounting groove or an adapter plate adapter plate for a mounting groove. In this configuration, a mounting groove is normally required.

Wildseyed Simple Hot End Mounting System

Note: Ensure that the cold-end either has a 5/8" mounting hole or can be drilled out to 5/8".

Follow the mounting instructions for the Wildseyed Simple Hot End.


Notes

General

  1. In the Mk1 version, the cold-end of the PTFE liner will need to be retained in order to prevent it from backing out of the hot-end. With some extruders, such as the Wade Extruder, the PTFE liner will easily be retained by the socket that retains the hot-end. If the liner is not properly retained, there is a high probability of the nozzle developing a leak.
  2. While printing ABS, if the nozzle clogs due to crystalized filament the temperature is most likely too high.

Testing

Prototype

  1. While this nozzle is experimental, initial tests have proven to be very positive. At the time this note was added, the prototype had printed for well over 20 hours.
  2. Further testing indicates that it is critical that the internal gap, between the brass and the PEEK, is completely eliminated. If there is a gap, the PTFE will tend to "flow" into the gap and create a place for the filament to form a plug.
  3. Since this nozzle, internally, is similar to the Makerbot Mk V, testing indicates that it is probably a good idea to taper the PTFE at the hot-end of the nozzle.
  4. Testing of units with the internal gap, at the joint of the PEEK and the brass, have resulted in early failure. Replacing the PTFE liner would allow the nozzle to continue printing.
  5. Even with the internal gap, after two weeks the the initial prototype nozzle is still working.
  6. After almost a month, the initial prototype nozzle is still working. Due to the gap problem, it needs to have the PTFE liner replaced around once a week.

Mk I

  1. Initial testing of a nozzle, with the internal gap problem resolved, is very positive.
  2. A nozzle has been successfully tested extruding PLA.
  3. Some reservations have been expressed regarding the mounting of the nozzle. (Maybe the fender washer should be the recommended method or another method should be devised?)
  4. Extruding PLA can result in an early failure of the PTFE liner. This failure has been prevented by both increasing the feed rate of the filament and using a cooling fan. This is to keep the filament from getting to hot too high up in the liner. A heat-sink may be required in order to provide a more adequate solution.
  5. Due to this nozzle successfully printing both ABS and PLA, this entry has been updated to "working".

Mk I with Heat Sink

  1. Nozzles, with the experimental heat-sink, have been printing successfully. At this time, none have been reported to have printed PLA.
  2. The experimental heat-sink has shown to help considerably when printing with PLA. The configuration, that worked best, had the heat-sink with a fan providing active cooling. The air, from the fan, was directed to blow over the heat-sink and not the nozzle itself.
  3. When printing 3mm PLA, the heat-sink has proven to be very consistent and reliable.

Mk III-B

  1. PLA has been printed with a 0.70mm nozzle. However, there isn't enough heat provided by the heater resistor so the print speed has to be kept down. As a result, there is not advantage using a 0.70mm nozzle over a 0.50mm nozzle when printing with PLA.

Mk IV Original Prototype

  1. The version 3 nozzle, with a 6.8 ohm resistor, was used for testing.
  2. PLA has been printed with an airflow directed through the milled vents.

Experimental Light-Weight Hot End

  1. An experimental hot-end was built with a fluted nozzle holder and an aluminum nozzle (v2). A 1.75mm liner was installed and it was sent out for testing.
  2. With a fan, to provide cooling, this nozzle has successfully printed 1.75mm PLA.
  3. The light-weight aluminum nozzle should be insulated in order to maintain the proper temperature.
  4. This nozzle leaked. This was most likely due to the lack of a retainer for the 1.75mm liner.

Possible Future Modifications

Implemented Or Working

  1. If the extruder will not retain the PTFE liner, it may be possible to install a 5/16-24 hollow-lock socket set screw (McMaster-Carr part number 91318A550 or 91301A150) in the cold-end of the nozzle holder. (This has been implemented in the MK II.)
  2. Using 5/8 x 1/2 inch rectangular brass bar stock, instead of 5/8 inch square bar stock, will eliminate 1 machining operation, slightly reduce the cost of the raw materials, and may reduce the machining time for other operations as there will be less material to remove.
  3. Either the total length should be increased or two versions should be made available. The longer version would have a 50mm thermal barrier and the liner (for the MK I) should have an initial length of 3 1/2 inches.
  4. A groove-mount design could be created. However, a hollow-lock socket set screw (above) or a custom hollow set screw would have to be used to retain the liner. (The nozzle holder blueprint has been updated to include this option.)
  5. Add a starting taper to the cold end of the PTFE liner. (This has been implemented in the MK II.)
  6. A heat-sink option could be added to the nozzle holder.
  7. It may be possible to convert 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. (This has been proven to work.)
  8. Use an aluminum nozzle made out of a high-strength aluminum alloy, such as 2024 or 7075. This should lighten the nozzle as well as improve the thermal conductivity of the nozzle. (Depending upon the alloy, the thermal conductivity, can be more than twice that of brass and an aluminum nozzle should be around 1/3rd the weight of a brass nozzle.)
  9. Turn the center of the nozzle holder down to 12mm and add fluting in order to provide cooling and weight reduction.
  10. Change to the 6.8 ohm heater resistor. The 6.8 ohm heater resistor has a smaller OD and, as a result, the heater block size could be reduced. (A prototype has been machined. Since it fits in a 13mm x 13mm piece of bar-stock, it is worth pursuing. The prototype weighs 3.1 grams.)
  11. Cut grooves in the nozzle holder to help keep the nozzle holder cold at the cold-end. (Grooves, with supports have been milled in a test nozzle holder.)

Testing Phase

Under Consideration

  1. Shorten the brass nozzle and reduce the number of threads. This will result in there being less brass to heat up and the heat-sink could be moved closer to the hot-end.
  2. Use an axial thermistor installed in a through-hole.
  3. Add shallow grooves, in the PEEK over the end with the 3/8-24 threads. This will add more surface area to the PEEK and may help with the cooling of the nozzle holder.


Rejected

Note: Rejected ideas may be re-visited in the future.

  1. Add the capability to mount a thermocouple.
  2. Improve the thermistor mounting by adding a clamp or retaining system.

Miscellaneous

  1. A Mini J-Head nozzle design has been started. This design is a heavily modified version of the J-Head Nozzle. (This design has been abandoned. However, it could be re-examined if there is enough interest.)
  2. This design could be scaled down to create a mini version using a 4mm OD and 2mm ID PTFE sleeve. (A prototype is under development and a wiki page will be created for it in the future.)

Weights

Note: All weights include the heater and heat sensor unless otherwise note. Weights may vary slightly from what is listed.

J-Head Hot-Ends:

Note: All weights are assembled hot-ends with a 50mm nozzle holder, for an overall length of ~62mm

  • Mk II: 27.1 grams
  • Mk II: 17.0 grams (With nozzle v2.)
  • Mk III: 21.9 grams
  • Mk III-B: 30.0 grams
  • Mk IV: 16.5 grams(?) (With nozzle v2 and v4 50mm nozzle holder.)
  • Mk IV-B: 25.6 grams (With nozzle v1 and v4 50mm nozzle holder.)
  • Experimental: 14.7 grams (With nozzle v2 and fluted nozzle holder.)


Other Hot-Ends:

  • Geared Extruder Nozzle (Original design with aluminum heater block and without hardware.): 29.7 grams

Working Examples

Pictures

Jhn prototype test a.jpg

First prototype in action. (Photo provided by Brian Briggs.)

Jhn pla test.jpg

A test print using PLA. A high filament speed was used and there was little tuning of Skeinforge as the goal was to see if the nozzle would print with PLA. (Photo provided by Anthony Aragues.)

Jhn w heat sink printing pla gear s.jpg

A five hour print, of a gear, in PLA. A J-Head nozzle (Mk I), with an aluminum heat sink, was used. Please note the cooling fan configuration. (Photo provided by Anthony Aragues.)

Videos

Printing A Gear