Mini J Head Nozzle
Release status: experimental
| Description | Mini J-Head Nozzle, Thermal Barrier, and Mounting Plate based on the J Head Nozzle.
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| License | GPL
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Contents
Introduction
NOTES:
- This page is under construction.
- More pictures, descriptions, etc., will become available when they are ready.
- The current pictures do not show a finished nozzle tip as it will be identical to previous designs. When these pictures were taken, it was a proof-of-concept for the thread sizes, internal dimensions, fitting of the parts, etc.
- An experimental unit has been completed and sent out for testing. Therefore, this entry has been updated to "experimental."
This nozzle has been designed as a drop-in replacement for the RepRap Universal Mini Extruder hot end.
Advantages
- Internally, the filament path is identical to that of an already proven design.
- If necessary, the PTFE liner can be replaced by using an off-the-shelf piece of PTFE tubing.
- A resistor is used as a heater. There is no need to wrap nichrome wire.
- Heat transmission is improved as there is no thermal junction where a separate heater screws onto the nozzle.
- Since there are no press-fit parts, it is easier to disassemble.
Disadvantages
- The brass nozzle requires considerable machining.
- Due to mounting considerations, this design has more parts than the standard J-Head Nozzle.
Parts List
| Quantity | Part | Description | Part Number |
| 1 | Mini J-Head Nozzle | Machined Brass Nozzle/Heater Combination | |
| 1 | Thermal Barrier | Machined PEEK Insulator | |
| 1 | Mounting Plate Insulator | Machined Internally Threaded PEEK Insulator | |
| 1 | Mounting Plate | Machined Rectangular Aluminum Mounting Plate | |
| 1 | PTFE Liner | 4mm OD, 2mm ID PTFE Tubing | McMaster-Carr 52335K32 |
| 1 | Heater Resistor | Axial, 5.6 ohm, 1%, 5W | UB5C-5.6-ND |
| 1 | Thermistor | 100K | B57560G104F |
Machined Parts
Mini J-Head Nozzle
Material: Brass Bar Stock, 5/8" Square Or 5/8" x 1/2" Rectangular, ? Long
Note: 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.
- Cut a piece of brass bar stock ?? long plus enough to adequately hold the stock in the lathe.
- 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.
- Mount the brass bar stock in a 4-jaw chuck on a lathe. Adjust the chuck so that the nozzle axis is on center.
- Turn the threaded end of the nozzle down to 0.375 +0.000 -0.004.
- MORE INSTRUCTIONS COMING SOON.
Thermal Barrier
Material: PEEK, 8mm Round, ??? Long
- Drill out the ID to 4mm.
- Turn down what will be the hot end to 6mm for a distance of ????.
- Cut a 30 degree taper on the tip of the hot end of the thermal barrier.
PTFE Liner
Material: PTFE tubing, 4mm OD, 2mm ID, ??? Long
- Using a razor knife, cut the tubing to length.
- Cut an approximately 30 degree (or greater) taper on what will be the hot-end of the PTFE liner.
Mounting Plate Insulator
Material: PEEK, 5/8" Round, ??? Long
- Cut a piece of PEEK to length plus enough to mount in the lathe.
- Turn down the shoulder to an OD of 0.500 -0.000 +0.0510. The shoulder will take up 1/2 the length of the PEEK insulator or about 0.125. (NOTE TO SELF--CHECK THIS)
- Using a letter size Q drill bit, drill out the ID.
- Internally thread to 3/8-24.
- Cut off the mounting plate insulator so that it is about 0.250 long. (NOTE TO SELF--CHECK THIS)
Mounting Plate
Material: Aluminum, 3/4 inch wide x 1/8 inch thick, 34mm Long
- Cut the mounting plate to the above dimensions.
- In the center (17mm from one end and 3/8 inch from the side) of the plate, drill a 1/2 inch hole.
- Drill both 3mm holes centered (3/8 inch from the side) 3mm from each end.
Assembly
