you are not not able to use external spool. To print TPU (and use tpu assist) you need to unplug FTS.
you will not able to set K-factor profile. You can assign K profile to filament, but printer will completly ignore it. For main extruder, that OK - there are auto flow dynamics calibration. For auxillary extruder - you will be printing without pressure advance. Keep it in mind if you are not happy with auto calibration for left nozzle or no calibration for right nozzle. As for me, I will not bother to do manual calibration. And I think there are workaround avaible: if you use M900 g-code in filament custom g-code, that may work - because printer still be able to set K-factor during print (as you can see if you print PA calibration test)
you have to deal with higher resistance added to filament path. You will not able to print some materials and you may face some faults during print
pros:
you will no more messing with spools to print it via main or aux extruder. As it loaded in any connected AMS - it may be routed in any nozzle automatically just for few mouse clicks in slicer
you can print two nozzles from one AMS. Yep there will be filament cuts and retracts to spool every nozzle switch, but there will be no poop purge to flush previous color from nozzle so you will save both time and filament compared to single nozzle dual color
Dynamic mapping - one filament can be routed to left or right nozzle during single print
Soooo FTS mainy QoL investment. If you are OK to deal with cons this is nice thing
If you are not using dynamic filament mapping and just want to be able to route AMS to left or right nozzle without messing with PTFE fittings - maybe better print manual PTFE switch, for example:
Btw if you want to set k-factor even with FTS, you can use M901 K0.5 (for auxiliary extrusion) and M900 K0.04 for direct extruder in filament start gcode
If you have an AMS Pro 2 and AMS HT and mostly print PLA or PETG the Track Switch will work just fine? I might try TPU for AMS in the future but I’ll just unplug the Track Switch no problem there for as little as I’ll use TPU.
Yes, the FTS will work with that setup (I’m assuming you have an X2D?)
If you use TPU for AMS you don’t need to unplug anything - although the system may struggle to push it through the FTS, so pay attention to your PTFE routing and lengths to avoid any sharp bends.
Bambu is also saying they’re working on finding a way to allow things like the TPU assist and external spool to work with the FTS, but it appears to be a controller limitation that they’re up against, so there’s a chance it won’t happen.
Thanks Man! I’ve been on the fence in getting one because of some of the negatives. The cons listed in this thread really don’t apply to me. I just really wanted to choose what nozzle what filament goes into. Kind of making the X2D an ALMOST TRUE multi color printer (I know it’s not but one can dream!)
The first one (1) is really annoying. I can’t understand why this is so.
The second point…How did you find this out? I manually tune all filaments because the auto calibration seems to be wildly inaccurate. I had no idea that the track switch ignores everything that I’ve done…Again…why?
I am really at the end with Bambu and these quirks that they never seem to fix.
I’ve been trying to tune TPU-LW and it’s a train wreck with this machine. I hate it.
I feel Bambu has fully embraced the printer and ink model. They rally aren’t interested in the people trying to push limits, they just want to sell 16 colours of overpriced PLA and encourage printing of excessive presliced crap from Makerworld.
Once i forgot to set K-factor for auxiliary and everything printed fine. I assume that there are still auto calibration on aux even if Bambu state there are not.
I printed four bambu cubes:
with k-factor profile set and flow dynamics calibration on
with k-factor profile set and flow dynamics calibration off
with k-factor profile unset and flow dynamics calibration on
with k-factor profile unset and flow dynamics calibration off
These cubes are absolutely 100% identical so i think there are no k-factor profile use in fts scenario at all.
Btw in stock aux extrusion profile acceleration set smth like 1000, so there are no critical dependence for pressure advance at all
Hey I have one more question if you don’t mind answering it! I just want to be clear that with the Track Switch I will be able to choose what nozzle has which filament correct? For instance currently PETG always goes to the auxiliary nozzle. I will be able to move PETG to the Main extruder and take advantage of its speed and accuracy, correct? Thanks again for your help!!!
I’ve thought about getting an FTS, but I keep ending back at the notion that it only takes about 30 seconds to rearrange filaments in my two A2Ps. And often times when I want to start a new print, at least one of the colors I need isn’t in either of my two A2Ps. And the other scenario is when the colors I need are all in one A2P. Combine that with the TPU challenges, and I don’t see the point.
By default, the operating principle Bambu uses is called “binding” - AMS1 is bound to nozzle1, AMS2 is bound to nozzle2, therefore only filaments in AMS1 are available to nozzle1, etc.
Adding the FTS removes all binding. Any filament can go to any nozzle.
Thanks for the response. So does it do the same for the main/left nozzle? If so I am throwing the FTS in the trash. Not really. But it’s potentially more trouble than it’s worth for now.
Sigh…
Like many of us, I spent years and years troubleshooting and tuning old RepRap/Marlin based machines. The absolute beaty of those machines is that you could open up the firmware on Notepad ++ and edit it, add in your own features, SEE what was/is happening and why, and FIX problems.
The mechanics of the machines and reliability was not great, but my X2D has been taken apart over 6 times and had many parts replaced. One intermittent fault lingered for 6 weeks, and I ended up repairing it myself as Bambu Support had run out of ideas and ghosted me.
The 2 pin connector for the chamber temp sensor was faulty, but intermittently, and it would cause the reported temp to be artificially high, which would then cause the machine to apply maximum chamber cooling. At the time I was printing a lot of ASA and nylon parts, so that was a train wreck. I happened to touch the connector whilst looking at the screen and saw the display temperature fluctuate wildly, so I cut the connector out and soldered the wires, which solved the issue.
At the same time, I may or may not have installed a switch inside the toolhead which either connects or bypasses a resistor to the left nozzle thermistor, when switched on it provides a +30C offset for the nozzle temp which allows PPA/PPS to print with proper layer adhesion. I shouldn’t have ever had to have done that, as the X2D is supposed to be for engineering filaments…But here we are, having to make physical workarounds because Bambu firmware is so locked down…
let me clarify that I cannot reproduce the issue with the K-Factor issue when using the FTS.
I did now several tests for you and wanted to share wisdom.
Test Setup:
Bambu Lab X2D Firmware v01.02.00.00 (v2 hardware revision, bought mid of July 2026)
AMS 2 Pro, Firmware v05.00.22.19
Filament Buffer Firmware v02.00.17.18
FTS Firmware v00.00.16.65
External Exhaust Fan Firmware v00.00.13.35
Bambu Studio Beta v2.8.4.57
Bambu Lab Basic Black (Flow Ratio 0.985, Cooling a bit retarded)
Nozzle temp Initial = 220°C, other = 215°C
Speed set to 200mm/s
Top Surface 75mm/s, Monotonic Line + Sub Top Surface
Line width 0.45, Top Surface 0.32
NO Ironing
LAN Mode enabled
Flow Dynamics Calibration = off
I ran from left to right the same settings above just with the following difference:
manual G-Code = M900 K0.00
no manual G-Code, Flow Dynamics Profile K-value 0.001
manual G-Code = M900 K0.021
no manual G-Code, Flow Dynamics Profile K-value 0.026
As you can see it works like it should at least in the configuration above.
Please, if you are complaining make sure to check if your general parameters are correct and you are comparing apples to apples.
I am curious to see if you can get the same or near same results as me.
Hope that helps
@Petrovich39
I did now run more tests just to verify on the auxiliary extruder.
Used the exact sameProcess Preset just some speed differences like “outer wall” are changing for the auxiliary extruder.
Also the Filament Preset is the same one. In the above test I did not use the manual G-Code = M901 Kx.â– â– â–
The right one on the other hand was using or assigned to the PA Profile of the main extruder which was at that time using a K-Value of 0.030 which as I would guess did not apply and instead a last saved from the auto Flow Dynamics Calibration was used.
So your take on “with the FTS it stops working” is (at least for me in the mentioned configuration) not true/valid.
On the other hand Bambu should do better as we may want to use our PA Profiles from both extruders on our filaments depending on the print job and color configuration.
Reduces risk and greatly improves User Experience.
@Bambu_support - Please have a look at the observations in this thread. This should be a must to implement.
