Many FDM filament dryers have a port through which you can guide the filament. This handy feature allows you to print from the spool without removing it from the dryer, saving time and limiting exposure to (moist) air. Unfortunately, these exit ports aren’t always thought out very well, mostly in terms of the angle with the spool as it unrolls. The resulting highly oblique orientation means a lot of friction of the filament on the side of the port. This issue is addressed in a recent [Teaching Tech] video, with a simple, low-cost solution.
The basic idea is to have a swiveling port, inspired by a spherical bearing. The design shown in the video uses a PC4-M6 pneumatic connector to pass the PTFE tube. Connector choice is critical here, as many PC4-M6 pneumatic connectors won’t accommodate the PTFE. As a fallback, you can drill out a connector to enable this.
Once the connector is sorted, you need a 13 mm (~0.5″) step drill bit to widen the opening in the filament dryer. This ready-to-print version has 10 degrees of freedom in any direction, but you can adapt it to fit your needs. With this mod installed, the angle with which the filament enters the port should remain as close to zero as possible, preventing both friction and damage to the port and filament.
The angle remains unchanged by the port. I was thoroughly confused by “the angle it enters the port is 0° “. I guess I was imagining this as relative to the original port angle.
Problem seems to be that the holders are round, where you need at least one corner if the ‘ray’ is to be cast off the circle at the diameter 90° to a radius line.
Confirmed, is a hack. Nice.
I use a much simpler solution on my sealed filament holder. The PTFE guide runs right through the box side and ends at the same height as the spool holder axle, acting both as strain relief and light brake.