Ideas for reducing AMS filament path friction


I have read a lot about AMS and i understand the problems with it on certain materials. However, I dont mind about the AMS system wear. I can always replace wearables. But what i really do need, is making my AMS print CF-PETG to make multi colored CF-prints.

I have studied the issues Im having. Printer prints fine from AMS with CF-PETG, when swapping colours, it cuts the filament correctly. However, when unloading, there is just too much friction in the system, and AMS cannot pull the filament back from the print head. Its friction problem, nothing else. At least in my case.

I would like to know why the unloading process happens over the waste chute, where the filament tube makes the tightest bend from the print head towards the back of the unit?
Why not to unload in one of the front corners of the print plate and then drive the print head over the waste chute? I could make some testing, but im not familiar with customizing g-codes. Every little thing and working or worth to try idea that reduces AMS friction would help at least in my case, as its not much thats needed to make the unloading work.

The PTFE tubes on the bottom are the pain in the ass to replace, every knick causes drag and every filament change causes more and more gouges I’ve heard of some ordering borax glass to bend and shape for the bottom of the AMS

I’ve had issues with glow filament retracting through the AMS also.
I would suggest changing all the PTFE tube for a larger internal diameter one and maybe creating some curved guides or use springs for the PTFE where it has to bend to prevent it from kinking. This was the fix for my prusa MMU which had similar problems with abrasive and less quality filaments with less consistent diameters.

Simply look your tubes are in an wide angle, with wide turns… that should be enough. I print things with thousands of color changes without retraction problems including cf. All i did i change the arangement of the tubes.

Thanks for the replies and suggestions!

I have disassembled the AMS to check if theres any PTFE tubes in straight angles. None.

The friction “problem” with the Form Futura CarbonFil is that the filament surface is very and I mean very uneven/grainy/textured when compared to some other CF stuff. But its the only CF filament that ticks all the boxes on my use.

Replaced my current extruder tube guide ( Printables ) with this shorter version: Printables

Now i got it to unload the first time on its own. It still kind of struggles, so I dont think its going to be perfect fix, needs more testing.

Thinking of testing this set: Capricorn Premium PTFE Bowden Tubes for 3D Printing

It would be perfect if they offered that set with XS Ultra low friction type, but no, TL only. Does someone have experiences on that Capricorn AMS tubing kit? Does the TL series have less friction than stock Bambu PTFE tubes?

That set is 3mm internal diameter, which is what I suggest you try instead of the BBL PTFE, which is 2.5mm. Capricorn PTFE is good quality.

Thanks, I´ll try that. It´s so frustratingly close that i would be able to print that filament from AMS.