Second AMS 2 Pro with FTS – Retraction Issue and Feed Resistance Errors

Bambu Lab AMS AMS 2 Pro
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I have an X2D Combo (including one AMS 2 Pro) for about a month. Recently, I added a second AMS 2 Pro and installed it using the Filament Track Switch.

The first AMS is mounted directly on the printer, while the second one is mounted on the wall behind it. During the very first print with the new (wall-mounted) AMS, I ran into an issue at the very end of the print where it couldn’t retract the filament. I then slightly adjusted the tube routing, and after that it was able to retract the filament again. With the first one, everything works fine.

This issue hasn’t occurred in the last five prints, but I am now repeatedly getting “feed resistance is too high” warnings in the app.

I’ve attached some pictures showing the setup and connections. I already shortened the tube between the AMS and the Filament Track Switch a bit. Do you think I should shorten it further or route it differently?

Thanks a lot for your support.

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2

Print the tube guides that Bambu recommends you use with the FTS. You printed and installed the brackets, but not the guides themselves.

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You’ve made an impossibly tight bend right after the AMS, it’s not at all surprising you’re having issues. I can see a kink forming in the tube in your first picture.

3

Thanks for your reply.
I’ve printed out the tube guides and am using them on my other AMS as well. With this AMS, I tried to install the guide facing downwards, but there wasn’t enough space between it and the wall, so I left it out. If I install the tube guide facing upwards or to the side, there should be enough space.
I’ll give that a try. Many thanks for the tip. I’d assumed the bend wasn’t too tight.

I hope the PTFE tube isn’t damaged now.

4

I’ve installed the tube guide, but unfortunately I can only position it facing upwards, or else I won’t have any space behind the wall mount.
This makes the route to the FTS longer, and the cable is now too short for that… I need a longer tube, but then I’d go over the recommended 700 mm.
I’d need about 750 or 800 mm.

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Print some spacers to go between the AMS rack and the wall to give you more space for the tubes.

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Yes, that would be one option. However, before I modify the wall mount and potentially make it less stable by adding spacers, I would like to explore some other possibilities.

7
  1. Adding spacers between the rack and wall doesn’t modify the rack, it just increases spacing to the wall. Stability doesn’t change from something like that, if the spacer is the full size of your contact patch with the wall there’s no functional difference than if it were mounted directly into the wall - provided your fasteners are also increased in length and you weren’t already marginal on pullout strength of the wall. I’m hoping you’re fastening into studs.
  2. The whole reason for the length limit is friction - you’re already dealing with excessive friction, adding more friction to try and reduce friction isn’t really a sensible approach fix this issue.
  3. Even if you can get the ultralong tube to work, you’ve just ensured every filament change will take as long as possible each time. That adds serious time to multicolor prints - hours in some cases. You also add a not insignificant of unnecessary wear to the motors.
  4. Neither of those guides will work, they require a relatively short tube into the buffer to control the overall shape, for a long tube they won’t prevent the tube from kinking right at the AMS.
  5. Both of those guides still need space behind the AMS, which you don’t have. You’d need a fairly sharp kink to use them, I expect.