Wye? Y? Thinking they really should be wye since that's what they are called in plumbing.

...ANYWAY...

Why another wye? Obviously because none quite worked for me. I had issues with friction and really bad luck with crappy imported pneumatic couplers. I kept getting to a point where filament would get stuck.

I wanted one that printed flat so that you didn't add unnecessary friction from layer lines all along the filament path…very significant, especially considering the serrations added by the AMS feeder. And I wanted one that didn't require couplers.

The closest to a perfect solution was Jaco van Zweel's Very Easy Y-Splitter and the remixes. But in my testing, these didn't grip the Bowden tube well, had an overly constrained filament path, and still jammed. So I reluctantly made yet another one---redesigned from the ground up, but obviously highly inspired by the above design.

What's notable:

• No need for pneumatic couplers
• Printed flat in two pieces to minimize friction and ease printing and assembly
• Optimized shape and size of filament path to minimize friction
• Added chamfers at start and end of filament path to (hopefully) eliminate snags
• Added simple barbs to greatly improve Bowden tube grip
• “False floors” to eliminate need for supports
• Registration “nubs” for alignment
• Support for either M3 threaded inserts or M3 nuts
• Support for 4 different common sizes of magnets

Fasteners:

• 6 of M3 x 6mm screws
• 6 of M3 x 4mm heat set threaded inserts

OR

• 6 of M3 x 8mm screws
• 6 of M3 Nuts

Magnets (optional):

• 2 of 10x3 round
• 2 of 8x3 round
• 4 of 6x3 round
• 4 of 5x5 round

Print 1 top and your choice of a bottom. These are very easy prints, just like the “inspiration” design. Recommended print settings:

• 16mm layer height
• No supports
• 4+ Shell Layers (top/bottom)
• 4+ Wall Loops (especially if you're using inserts)
• Aracne Wall Generator (slightly better for the barbs)

I'm using Polycarbonate (PC), but I think any filament really should be fine. This isn't seeing any real heat or stress, and there's very minimal wear from the filament passing through.

Assembly is simple:

• Add the threaded inserts or nuts.
  • Threaded inserts can “rest in place” on the slight recess above the holes, which helps a lot with alignment.
  • The nuts should be a tight friction fit, so sandwich the nut between a hard table top and the splitter bottom and press down firmly.
• Optionally add the magnets.
  • These too should be tight friction fits, so a table sandwich (or pliers, I suppose) will be needed.
• Insert the screws into the top.
  • You may need to press firmly to start in order to break through the thin false floor.
  • You may also need to screw them in to start as the tolerances are pretty tight.
• Firmly affix all 3 tubes to the bottom.
  • They should stay in place pretty well as the barbs will “grab” them.
• With all three tubes in place affix the top.
• Screw the top down snugly.

For Bambu Lab users, the single tube (output) side will attach to the tube that enters the printer at the top. One of the two input tubes will probably connect to your AMS. The other will attach to the length of tube that you will use to manually load filament.

I replaced the factory-supplied coupler entirely (see picture). For me, this was a significant source of friction, and this new splitter has actually reduced friction compared to the factory configuration. YMMV.