Let me start of by saying that I did not design this or come up with the concept. Stranula on ********** deserves all the credit. I simply redesigned his model to make it slide better and use PC4-M10 PTFE connectors.

I am very happy with the results of this filament buffer as it has seemed to eliminate any pressure on the PTFE tubing and should take a lot of stress off of the CFS itself. There has been no CFS filament grinding, PTFE tubing coming out or errors (CFS or extruder) since installing this. I've also been able to lower my flushing volume down to .9 with no bleed.

Original: https://www.**********.com/model/1190380-inline-filament-buffer-cfs-ams-helper-beta-version

Everything below here is quoted from the original designer (Stranula) except for a few minor alterations that were required for my remix.

This inline filament buffer was designed out of the desire to use retract before cutting on the K2 Plus with CFS. When we first tested this idea, we found that the retraction caused a great deal of pressure in the PTFE line, often causing it to pop out of the extruder, requiring user intervention to correct. Additionally, that connector is failing prematurely for many users, so we do not want to put any additional stress on it.

This version of the inline filament buffer will allow ~20 mm of travel with minimal pressure on the line. Presently, I am limited by the length of spring that I have, but I will be making another version for a longer spring once I get those springs.

Here is a slice view of the buffer after I remixed it.

The filament enters from the right side, extruder is on the left side. When the extruder retracts, it will compress the spring , thus lengthening the overall line distance.

You will need a spring.

I am using a 5.5*38 mm spring from https://a.co/d/bf6kvWy

You will also need:

4x M3x10 screws https://a.co/d/3hIJZWj

2x PC4-M10 PTFE connectors https://a.co/d/ch6Hxnw

You can then edit your machine g-code in your slicer for the change filament G-code section to the following

G2 Z{z_after_toolchange + 0.4} I0.86 J0.86 P1 F10000 ; spiral lift a little from second lift

G1 X0 Y245 F30000

{if toolchange_count > 1}

G1 E-20 F200

BOX_MOVE_TO_CUT

G1 E25 F200

G1 E-28 F200

{endif}

G1 Z{z_after_toolchange} F600

This will do the following

1. Perform spiral lift

2. Move to cut position

3. Retract 20 mm

4. Extruder 25 mm to push the cut tip back down in the nozzle

5. Retract 28 mm to make sure the filament tip is clear of the cutter

6. Then it will proceed with the filament change.

Inline Filament Buffer (CFS & extruder helper)

0.16mm layer, 3 walls, 10% infill

0.2mm layer, 2 walls, 15% infill