Bambu AMS Replacement Feeder Funnel

This is a model for the full first stage feeder funnel.  If you print abrasive materials with carbon fiber or glass fiber from the AMS, it starts to grind away at a lot of different parts.

If you print the top portion of the feeder funnel in a stiffer material, it should last longer than the original!

https://us.store.bambulab.com/products/ams-feeding-funnel

This model is split into 3 parts to make the print easier.  My hope is that we as a community can customize the feeder funnels by plugging on a different top funnel design onto the main body and arrive at a more reliable design than Bambu's.

• bambu_funnel_top: The funnel part that is begging for a redesign.  This is a recreation of the stock design (for now)
• bambu_funnel_middle:  The most complicated part and houses the filament runout sensor and roller bearing
• bambu_funnel_buttom: This reuses the clip and PTFE fitting

Some topper ideas for inspiration:

• A PTFE fitting, which would work better than other attempts at making a cap to place on top of the stock feeder
• A bar with roller bearings 

Printing

The feeder funnel is a complex object and a little bit difficult to print.  The top and bottom is easier.  Just print them with the largest flat surface on the build plate.

For the middle section, orient with the side facing down, and choose the side with the shortest cylinder.  If you're facing the “front” side of the feeder if it were installed in the AMS, this is the left side.  See the bambu_feeder_rebuild_kit.3mf for a better description.

Print the middle and bottom in PLA with a 0.2mm nozzle.  You can attempt a 0.4mm nozzle, but I don't think it's going to work.  For the top funnel, you can get away with a 0.4mm nozzle and an abrasive filament.

Assembly

Take the 3 pieces of the body and glue them together with epoxy, then clamp tight to dry.

Use a small Dremel bit to clean out all of the small pockets.  Use a drill bit to ream out the filament tunnel.  If you have a 2mm bit that would be perfect.  If you only have Imperial bits, start smaller and test fit a piece of filament through the funnel and feel for anything that catches.

Plop the filament sensor thing into the slot, flat side up.

Screw the PCB onto the funnel feeder and test.  Use a digital multimeter to probe pads TP7 and TP8 on the bottom of the board.  These are connected to the filament runout switch.  Slide a piece of filament in and out and confirm that the circuit closes with filament IN, and opens when filament is OUT.  (This might require an extra set of hands)

Install the PTFE fitting and the clip from the original feeder.  

Install the roller bearing and install the feeder funnel into the housing.

Reassemble the rest of the first stage feeder, and bench test it with 6VDC.  If you stick a piece of filament in the funnel and apply voltage in the correct direction, the motor should feed the filament through and spit it out the PTFE fitting.  This test is a must if you printed gears too.  It saves yourself a lot of time disassembling the AMS.

If everything seemed to go well, reinstall the feeder into the AMS and try out some prints!

Gears!

Check out my other model if you're looking for replacement gearsets for the AMS First Stage Feeder:

https://www.printables.com/model/461711-bambu-ams-feeder-rebuild-kit