Filament Splitter for Bambu X1C UPDATED

Bambu Feed Splitter UPDATE

Purpose

Many versions of these are available on the site.  They attempt to solve a basic problem when dealing with the AMS.  There are filaments that will not a few the AMS for a few reasons.  This means that you may find yourself continually connecting and disconnecting the AMS feed to use a manually fed filament.  These provide a simple bypass of the AMS pass so there is no need to connect and disconnect.

The Old Part

For PTFE tubing, a fitting must actually bite the surface of the tubing because compression will not hold. Teflon has serious cold flow and will loosen.  This is the purpose of the metal fittings. 

My first try was with M6 fittings which have a hole big enough for the filament to pass.  It failed frequently with the filament hanging up inside the fitting.  The version that I put up uses an M10 which actually allows the housing to pass thru the fitting and into the part so I have complete control of the path.  

I printed my first version with very little thought.  I sliced it I ran it for a couple of weeks without problems and it worked, so I posted it. It turned out that I had done and failed to communicate some details that were important, and a few people had problems.  I tried to fix it and I was having problems with overhangs, oval holes and thread problems.  It turned out that I was having layer rounding issues.  It also had some real problems with BASF HTPC-CF filament not wanting to go through.  The update should address those issues for most people.

Changes

I have gotten better at refining parts for FDM and the new part reflects those changes.  First, I replaced the cylindrical overhangs on the bottom of the part with 45deg chamfers.  Then I adjusted the bore height to print more nearly round holes for the filament bore, specifically for a 0.16mm layer height.  I put a relief in the top of the tube guiding bore to reduce hole sag on the top overhang.  I adjusted the M10 threads a bit.  All in all, it prints and works a lot better.

Printing

I used PETG with a 3mm retract 20mm/sec retract speed and a .4 Z hop.  Stringing in the curved bore is hard to clear so it is good to have low stringing.

Layer height should be 0.16mm including the first layer.  Other thicknesses may not produce round holes for the filament and housing bores.

I used 15% Gyroid infill and 3 walls, but there is nothing special about that

Monotonic seems to be good for top and bottom layers.  I was using concentric, on the top but it tends to leave boogers in the filament bore.

I am using 60mm/s for the outer walls, slower will probably give you better threads.

I use a 5mm brim but it is probably not required. 

Don’t use supports.  The notch on the top of the housing bore should solve any overhang sag issues.  The zigzag of the threads seems to keep them from drooping

Installation

Finishing the ends cleanly and completely inserting the tubing in the pilot bores is very important.  When you cut the tubing, it will probably be flattened.  Make sure the face of the cut is square to the axis and use an awl or similar device to make the tubing round again.  Don’t stretch it.  Clean up any burrs or hangnails.  

For insertion, screw in the fittings, then press in the tubing.  You should feel it initially stop as it hits the plastic, but continue pressing until you are sure it is bottomed out in the counterbore.  This should eliminate almost all hangups.

On the machine, I position exit fitting up against the elastomer feedthrough and double stick it to the back face of the machine.