Description

A filament guide for moving spools off of the top of a Neptune 4 Plus/Max/(pro?, normal?) while securing the sensor yet allowing for free movement.

The top filament guide and holder for the runout sensor should work for any recent Neptune, while the side filament guide might need trimming to work on a printer other than the 4 Plus and 4 Max (If anyone who has one and is interested in giving me some detailed measurements, please leave me a note).

This is very handy for printing from a drybox or filament dryer.

Non-printed Parts

You will need the following non-printed parts to complete this.

• Any 608 bearing (does not need to be a higher speed bearing with skateboard oil, any greased version should work fine)
• PC4-M10 fitting (the kind that PTFE tubing can fit all the way through)
• Length of PTFE tubing. Any appropriate length should work. I'm starting with a 1 meter length and it reaches my dryboxes either on the front side of back side of my printer with a fair bit of slack.

Printing

First print all needed parts (you can skip the spacers if you have short M4 screws or just don't want to bother). Also you will need one 608 bearing and one PC4-M10 fitting. The files are already oriented for printing.

I've uploaded both STL and STEP versions and grouped them into their respective folders. I'm currently using OrcaSlicer and printing directly from STEP files, but know that others prefer STL files.

Assembly

Arm → Bearing

Push the arm into the 608 bearing until it seats against the wider ring.

Bearing → Base

Press the 608 bearing with the arm facing the shorter side of the base.

Plug → Bearing

Insert the plug into the back of the bearing.

Once it is in place, push firmly as far as it will go into the bearing.

PC4-M10 → Runnout Holder

Line up the PC4-M10 fitting into the threaded opening and tighten it firmly, stopping before it becomes too hard and cracks the printed piece. A few turns should be enough to hold it in place, so don't worry if it does not screw in fully.

Runnout Sensor → Runnout Holder

Start to seat the runnout sensor into the runnout holder, gently pushing out the two clips without breaking them. (don't worry if you have issues with the clips, they are mainly just there for an extra bit of caution)

Once it has passed the start of the clips and is fairly even and level, firmly push the runnout sensor in the rest of the way to seat it. The clips should spring back into place and the holes of the runnout sensor should be lined up and visible in the top and bottom.

Runnout Holder → Arm

Gently line up the runnout holder with the two slots in the arm, with the bottom of the sensor going in first. Hold your finger underneath the slot in the arm to brace it before applying pressure.

Once things are lined up evenly and braced, gently push the round pegs of the runnout holder into the slots while bracing the back of the slots until it seats.

Don't worry if there it might not seem fully seated, as the extruder will pull on the filament from below and bring it into place. As long as it can rotate somewhat it should be fine.

PTFE tubing → Side Guide

Push the end of the PTFE tubinng up through the bottom of the side guide. Do not worry at this point of getting the length exact. Just get it in (possibly shaving the hole a bit if the tubing does not pass through without excessive force).

Side Guide → Top of Printer

Gently center the side guide on the top of the printer above the two screws on the top, then push down until it clips on.

Spacers → Screws (optional)

If you want to reuse the existing screws from the standard filament mount, slide them on the screws at this point. If you have shorter M4 screws you will not need these.

Screws → Base

Holding the assembled pieces, set the screws in place on the two holes in the base.

Screws → T-Nuts

Carefully line up T-Nuts with the screws then start each screw into the corresponding nut. Be sure to get both slightly started before tightening both. 

PTFE Tubing → Runnout Holder

Firmly press the PTFE tubing into the runnout holder until you feel it pass all the way through the fitting and butt up against the runnout sensor itself.

Connector → Runnout Sensor

Re-attatch the cable into the runnout sensor.

Adjust the PTFE Tubing

Push the PTFE tubing up through the side guide until the runnout sensor is roughly vertical.

Secure the PTFE Tubing

Wrap a short piece of electrical tape around the PTFE tubing just above the side guide to prevent it from slipping down over time.

General Usage

At this point it should be ready for use, and just needs the following to load a filament.

Feed the Filament

Feed the filament up through the free end of the PTFE tubing until it comes out the bottom of the runnout sensor.

Once it comes through it should activate the sensor and be ready to pull down and load normally.