Y-Splitter for the Bambu Lab X1C AMS

Update 2023-08-01 #2: NEW VERSION! 
I have created a new and improved “no-catch” y-splitter

Check out and download the new version here:

Bambu AMS No-Catch Y-Splitter PC4-M10

I want to thank everyone who who downloaded and posted makes and comments. I hope you find my new design even better than this one!

Update 2023-08-01: I added a PTFE cap to cover the PTFE tube when not in use to address concern over air leaking into the AMS. I'm not sure how much of a real problem this is, but for those in humid environments, it seems like a valid point. I uploaded a separate model (PTFE Cap for Bambu Lab AMS Y-Splitter) along with updating the files here.

This is my take on yet another y-splitter for the Bambu Lab X1C AMS unit. This design uses PC4-M10 PTFE connectors and has a deeper hole to insert and hold the PTFE tubes securely. I also designed a clip that screws to the corner side panel to secure the splitter. I have included my Fusion 360 source file to make it easier to remix if you like.

Printing

Print the splitter standing up with the bottom of the “Y” on the build plate. I designed this so no supports are needed, but you should use a brim to reduce the chance of the part breaking loose. The clip prints with the flat back on the build plate and also doesn't require supports. I printed my parts in PETG at 0.2 layer height on my X1C and they required minimal post-processing (details below and in the video).

There are three different versions of the splitter included in the files section. They only differ by the amount of clearance around the threads (0.0mm = no clearance, 0.05mm, and 0.10mm). I printed the 0.05mm version on my X1C and I was able to hand tighten the fittings most of the way. I snugged them up with few gentle turns with a wrench (don't overtighten or you can strip the threads!) I suggest printing the .05mm version to test the fit and then go up or down from there if you need to.

Tools and Parts You Will Need

Tools:

• 2mm hex wrench
• 2.5mm hex wrench
• PTFE tube cutter or utility with new blade
• 10mm wrench or adjustable wrench
• Small chamfering drill bit or diamond coated needle file
• Calipers or ruler

Parts:

• 3D printed y-splitter and mounting clip
• 3mm x 6mm socket head screw 
• 3 x PC4-M10 PTFE connectors
• 1 length of PTFE tube cut to 45mm - 50mm
• 1 length of PTFE tube cut to 70mm - 100mm
  • Note: PTFE tube must be 4mm outside diameter x 2.5mm inside diameter. This is the same size used and provided as a spare by Bambu Lab.
    1 length of filament ~150mm long for testing

Assembly and Installation

Step 1 - Disconnect the PTFE Tube
Disconnect the PTFE tube from the rightmost side of the coupler by depressing the spring loaded fitting and pulling the tube out. You will be reconnecting this to one side of the y-splitter later.

Step 2 - Cutting PTFE Tubes
It's best to use a PTFE tube cutter if you have one, but if not, it's fine to use a utility knife. Make sure you have a sharp blade and make sure to make the cut as square as possible.

Cut a length of PTFE tube 45mm-50mm in length from the spare PTFE tube that came with your printer. It is important to use a tube that is 4mm OD x 2.5mm ID. Most common PTFE tubes for 1.75mm filament have an inside diameter of 2.0mm. We need the larger inside diameter to ensure the filament moves freely through the tube. This piece will be fitted to the single leg on the y-splitter (the output side).

Cut another length of PTFE tube 70mm-100mm for the other side of the "Y" side of the splitter.

Step 3 - Install the Threaded PC4-M10 Connectors

Being careful not to cross-thread, screw in the 3 PC4-M10 connectors into the splitter. Hand tighten them as far as you can and then fully secure them with the M10 or adjustable wrench. Don't overtighten or you may strip the threads.

Step 4 - Insert PTFE Tubes
Insert the short piece of PTFE tube you cut firmly into the single leg side of the y-splitter. Make sure the tube bottoms out.

With the engraved text facing you and the top of the "Y" facing right, insert the second piece of PTFE tube you cut into the upper fitting, making sure it also bottoms out.

This is a good time to test the operation of the splitter. Take a short piece of filament with the end cut square and slide it into the tube on the right side. Push it until it slides out the left side. It should move through the splitter easily with little resistance. Repeat the same test pushing the filament through the leg without the PTFE tube. It should also move through the splitter without resistance.

If you do feel the filament "catch an edge", double-check to make sure the tubes are cut square and are pushed in all the way. It might also help to carefully apply a small chamfer to the inner diameter of the tube ends inserted into the splitter. I used a chamfering drill bit, but turned it by hand so I didn't remove too much material. If you are careful, a sharp utility knife will work too.

The other thing that helps is to carefully drill out the inner 2.5mm holes in the splitter using a 2.5mm hand drill. This cleans up the top edges of the holes to help the filament move smoothly along the path.

Once everything is moving freely, you can insert the PTFE tube you disconnected in Step 1 into the bottom leg of the "Y", again making sure it is inserted all the way and bottoms out. You will want to make sure this tube is routed under the spool holder.

Step 5 - Mounting Clip
Snap on the mounting clip with the slot facing up and the flat side facing the printer.

Insert the PTFE tube on the left side into the coupler feeding the extruder. This connection has a very short amount of travel before it bottoms out. You should only have a few millimeters of PTFE tube visible between the coupler and the y-splitter.

Using a 2mm hex wrench, remove the right-most screw from the corner radius on the cover. Using a 2.5mm hex wrench, insert a 3mm x 6mm socket head screw through the slot in the clip and secure the clip to the corner hole.

Step 6 - Test the AMS
You can test that the filament loads and unloads easily from the AMS by doing a couple of Load/Unload operations from the printer's touchscreen.

Step 7 - Test the Spool Holder Filament
To test the filament loading and unloading from the spool holder, make sure the filament is unloaded from the AMS (there is no filament visible in the PTFE tube coming from the AMS).

Make sure the end of the filament on the spool holder is cut square and is feeding from the bottom of the spool (it will turn counter-clockwise as the filament is fed into the extruder). Insert the filament into the short PTFE tube on the splitter and push it all the way in until it hits the extruder. Using the touchscreen menu, perform a load operation by selecting the spool holder location on the AMS tab. The printer will display prompts to guide you.

Warning!
I have been using this setup regularly for a couple of months and it works great. Just remember to use the unload operation for the spool holder when you want to switch back to the AMS. The latest printer firmware makes this process more user-friendly.

It's also worth noting that you have to make sure you unselect the AMS option when you send jobs to the printer if you are printing from the spool holder.

Thanks!

I hope you find this useful. Please share your make and let me know in the comments if you have any questions.

Links to some items similar to what I used (not affiliate links):
Diamond Coated Needle File Set
https://www.amazon.com/Yakamoz-Diamond-Triangular-Riffler-Jewelers/dp/B092D6KFN9

Bambu Lab 4mm OD x 2.5mm ID PTFE tube
https://us.store.bambulab.com/products/bambu-lab-ptfe-tube-3-pcs-370mm-1-550mm-2
https://us.store.bambulab.com/products/bambu-ptfe-tube-8pcs

PC4-M10 PTFE Connector
https://www.amazon.com/BIQU-Straight-Pneumatic-Connector-Extruder/dp/B01IB81IHG

PTFE tube cutter
https://www.amazon.com/PTFE-Teflon-cutter-tube-Allen/dp/B0756D2T73/

Countersink drill bit set:
https://www.amazon.com/dp/B07MCS2441?psc=1