Dry Box Pass-Through with Magnetic PTFE Coupler

This pass-through is designed for filament dryers or dry boxes. It consists of a threaded connector combined with a magnetic interface. The threaded connector requires a 0.5” (13mm) hole in the box, and is secured by a nut screwed on from inside the box. The connector has a flared, conical opening on the inside of the box to make it easier to insert filament from the spool. After designing this for my filament dryer, I realized that the holes on my RepBox dry box are also 0.5” diameter, so this pass-through is compatible with the RepBox.

Included is a model for a mating magnetic coupler with a PC4-M6 connector to attach the 4mm PTFE tubing. If you prefer to use a PC4-M10 connector on the outside, the magnet spacing on the external coupler is compatible with the “NoOffset” model found here: https://www.printables.com/model/32368-join-ptfe-tubes-together-magnetically/files. The magnetic couplers use 5x5mm magnets (press-fit) such as these: https://www.amazon.com/gp/product/B07JNT512N

Also included is a model for a magnetic solid cap to close off the hole when the pass-through is not being used.

2025-02-18 Update: Per request, added a washer for the Creality Space Plus double-spool dryer; it is necessary due to the location of ribs on the enclosure.  The washer is installed on the inside, over the threads of the dry box connector, before adding the nut.  One washer is required for each pass-through.

2025-06-05 Update: Corrected the link to the PC4-M10 “NoOffset” model.

Required Parts:

1x  PC4-M6 connector

6x  5x5mm magnets

Optional Parts (for Magnetic Cap):

3x  5x5mm magnets

Printing Notes:

• Print using PETG at 0.15mm layer height, with 15% gyroid infill.
• No supports required for any of the parts.

Installation Instructions:

Pass-through Assembly:

1. Press three 5x5mm magnets into the pass-through connector until they are flush with the surface; make sure that all three magnets have the same polarity.
2. Temporarily attach three more magnets to the magnets already in the connector (this ensures proper polarity for the coupler and makes them easier to insert). Line up the PC4-M6 coupler with the magnets and press the two pieces together to partially insert the magnets, then separate the coupler from the connector and press the magnets fully into the coupler until they are flush with the surface.
3. Screw the PC4-M6 connector into the coupler. It should be snug so that there is no internal gap, but no need to go crazy over-tightening them.
4. Drill a hole (or enlarge an existing hole) in the box to 0.5” (13mm) diameter.
5. Insert the pass-through connector from the outside.
6. If installing on a Creality Space Plus double-spool dryer, slide the washer over the threads, otherwise skip to the next step.
7. Screw the nut onto the connector from inside the box. It can be hand-tightened (no need to use a wrench).
8. Attach the 4mm PTFE tube to the PC4-M6 coupler and attach the coupler to the pass-through connector.

Magnetic Cap Assembly:

1. Temporarily attach three more magnets to the magnets already in the pass-through connector (this ensures proper polarity for the cap and makes them easier to insert). Line up the cap with the magnets and press the two pieces together to partially insert the magnets, then separate the cap from the connector and press the magnets fully into the cap until they are flush with the surface.