This project is an upcycling opportunity for some tubing that I bought in error and was destined for the trash. Moreover, it presents a chance to complete a task that I've been meaning to do for a long time. My magnetic PTFE joiners are my most popular design ever published, with hundreds of downloads every month on Printables and even more on Thingiverse. I consider it as a significant achievement. However, I identified some flaws in the design that require fixing. Therefore, it's time for version 3.
As the Rocky Mountain RepRap Festival approaches, I would like to showcase my work on a larger scale. I will have a table to present, which makes this upcycling project an ideal opportunity to create a table piece that represents my design ideals.
I have made significant progress in my CAD skills and preferences since I first released my PTFE joiners. I want to add some quality-of-life updates and improve the CAD structure. As the structure relies on the dimensions of the PTFE-fitting interface, which needs the most work, updating the design requires a full rebuild from the ground up.
My final product is an arching interactive sculpture piece consisting of my PTFE Joiners, tubing, all fastened together using Skadis.
These printed parts allow you to join together 3D-printing tubing to make easily accessible filament paths. They are my most successful design to date, but I want to use this project to develop the new version.
One thing I wanted to add to the previous design was an inheritance-based structure to the CAD. By rebuilding the interface for the PC4-M10 fittings in a separate file, I can import it into any project that requires that interface. This allows me to make changes to the interface and have those changes propagate across all files that require updating.
I encountered an issue where Fusion lacks many standard thread sizes, and one of the missing sizes is M10 PTFE joiners. Although previous versions worked, it always concerned me that cross-threading could occur in the soft plastic. There is a workaround to add custom threading, but it does not support tapered threading surfaces. Nonetheless, it should suffice for now.
Creating custom threads and thread standards in Fusion 360
After several iterations, these are the settings I have found to work best so far:
<?xml version="1.0" encoding="UTF-8"?>
<ThreadType>
<Name>Custom Threads</Name>
<CustomName>Custom Threads</CustomName>
<Unit>mm</Unit>
<Angle>60</Angle>
<SortOrder>3</SortOrder>
<ThreadSize>
<Size>10.0</Size>
<Designation>
<ThreadDesignation>PC4-M10 Internal Thread</ThreadDesignation>
<CTD>M10x0.9</CTD>
<Pitch>0.9</Pitch>
<Thread>
<Gender>internal</Gender>
<Class>6g</Class>
<MajorDia>9.8</MajorDia>
<PitchDia>9.32</PitchDia>
<MinorDia>8.87</MinorDia>
</Thread>
</Designation>
</ThreadSize>
</ThreadType>
These parameters create a thread that can be tightened by hand for most of the way, and then requires a wrench to be tightened for the remaining half turn.
This new version includes several key changes. First, we modified the interface for the PC4-M10 pneumatic coupler. It became clear that the original design had some differences from other common couplers of the same size. As a result, many users were unable to screw the couplers in all the way because their couplers didn't have a hollowed-out portion at the bottom. This new design forgoes the inserted tubing catch and instead uses a simple guide at the base.
Secondly, I initially intended to insert the magnets from the bottom to enable offsetting for alignment. However, it turns out that this is less important than I expected. In this new version, the magnets are inserted from the top, making it much less likely for them to be pulled out over time.
Lastly, I chose a pattern of four magnets with alternating polarities. This allows any coupler to connect with any other because the polarities will always match as long as they are rotated a bit.