I’ve seen that the upcoming OTA firmware update will let us combine AMS 2 / AMS 1 / AMS HT. My question is: Why isn’t AMS Lite included?
I’ve searched around and found other AMS Lite users asking the same thing, but I couldn’t find a definitive answer. Some comments claim it’s due to a mechanical limitation of the AMS Lite: if you add a hub to connect both AMS Lite and other AMS units to the printer, the AMS Lite supposedly can’t retract far enough to pull filament back through the extra hub. The reasoning given is that filament from the AMS Lite is retracted passively by the spool holder’s spring-rewind mechanism, so it can’t achieve the required retraction distance.
I don’t agree with that. In the AMS Lite, retraction is performed actively by the feeder motor, not passively by the spool holder. There are numerous AMS Lite mods on MakerWorld that remove the spool holders entirely and still work fine. I’m using one of those mods myself, and I’ve confirmed that the motor actively retracts filament from the hub.
So, if the firmware simply allowed a longer retraction distance, wouldn’t it be possible to combine an AMS Lite with AMS 2/AMS 1/AMS HT via an additional hub? Am I missing something here, or is there another reason Bambu Lab won’t allow this combination? It even seems like it would be financially beneficial for the company—without compatibility, AMS Lite owners may hesitate to buy new AMS products because they’d have to abandon their AMS Lite.
Follow-up question about AMS Lite retraction: why doesn’t Bambu Lab allow fully automatic filament unloading? There’s an “Unload” button for each AMS slot, but it only unloads from the extruder. If the feeder motor can actively retract filament, why not allow an automatic retraction to fully unload from the AMS slot? Manually rewinding filament to unload from the slot is pretty inconvenient.
My immediate thoughts (prior to any actual launch and no visuals) is simply that they operate very differently.
The AMS Lite has four PTFE tubes that can and do have the filaments pushed almost all the way to the head.
With only a couple of inches of filament difference between the one pushed into the hit end and the other three staying just outside.
The mechanical design of the spring loaded spool holders controls the return path rather than the motors.
All other AMS units do it differently. There is only one PTFE tube from the AMS to the print head and all the filaments stay inside the AMS unit, this distance is equal to the length of the PTFE tube. The filament requested is the only one pushed and pulled by motors to the print head.
To use two AMS units, you would require just two PTFE tubes, with one AMS and one AMS you would require 6 PTFE tubes and if the original announcement was true, a brand new way of getting the filament back to the new position required under the new system.
The long and the short of this is it is far more than how many PTFE tubes are involved.
It is the mechanics of connecting up two different mechanisms of getting the filament to and from.
In short, the AMS lite is designed to keep the filament near the head, the AMS units are not p.
Again, if the original design choices announced at the launch of the A series are to be believed, it is that difference that makes this a process likely to complicated for them to bother.
AMS Lite was a comprimise for the A series. A big thing is that the sprung AMS hub is literally on the toolhead, instead of floating around back of the machine. This changes a LOT of the dynamics as the spring pressure gets transmit differently (more directly?)
Bambu’s software engineers can’t figure out how to combine 0.2mm and 0.4mm nozzles within one print on their flagship, they aren’t going to figure out managing multiple retraction, feeding, and pressure strategies within a print due to the differing ams systems on a printer they look ready to discontinue…
//i still think the AMS lite would be brilliant if marketed to any-printer, not just bambu. It’s guts and method for attachment would suit well for most machines. Look at the stuff flashforge etc have built and tell me it isn’t just an AMS lite with the bits and pieces rearranged… coulda been a sale of an ams lite!
Thanks for sharing your thoughts. You’re right—the fact that the AMS Lite has four outputs while the other AMS units use a single output makes mixing them complicated. But what if we attach the 4-to-1 AMS hub (the one already in the BL store for 16-color setups) to the AMS Lite so its four tubes are merged into one? An AMS Lite fitted with that hub could then be treated just like an AMS1/AMS2, with no extra handling needed after that.
Of course, BL would still need to make the hub officially compatible with the AMS Lite, but that feels like a relatively small firmware tweak. As you said, it’s still work - and it may not be high on their priority list. It likely seems to depend on how important they think the AMS Lite market is.
I just hope they don’t discontinue the AMS Lite entirely. Once AMS1/2 works with the A1 series, some people might see the humidity-prone AMS Lite as less competitive. Still, BL could position it as a budget AMS option while keeping a clear upgrade path for users down the road.
It is more than the 4 vs I outputs and the likely issue is far more about how each type of AMS pulls back the filament, one using motifs, the other (lite) using springs. The mechanical return is different to the motor based version and it is unlikely that both can cohabitate together,
wait, do you mean the filament retraction of the AMS Lite is actually done by the spool holder’s spring rather than the feeder unit motor?
If that’s true,
shouldn’t AMS Lite mods that removed spool holders not work properly? As far as I understand, spring mechanism of the AMS Lite’s spool holder is just for an additional function to rewind the spool in order to prevent possible tangling of the filaments - not really a necessary function.
Another concrete evidence that the feeder motor performs retraction is that, at the start of every print, the AMS Lite retracts all four filaments from the extruder during the ‘checking filament’ stage. If you repeatedly print with the same filament, the other three end up parked far away from the extruder. This clearly shows the AMS Lite is capable of retracting filament a considerable distance.
Yes, that’s exactly what I was talking about. and I believe that the idea of the rotary spool holder responsible of the filament retraction is a widely spread misconception.
The spring inside the spool-widget is for handling rewind, instead of having a buffer (like the prusa). It also provides a gentle tug
The spring in the toolheads buffer path helps even out the force during feeding irregularities. It’s position being directly at the infeed mean it’s losing no energy in downstream ptfe friction. It also provides it’s normal force into the toolhead instead of strapped onto the frame somewhere, which I suspect is beneficial
I couldn’t find anywhere in the official doc or video explicitly describing which part of the ams lite is responsible for filament retraction. That’s why I had to deduce from observing the operations. And still, I can’t get off with the idea that it’s the feeder motor that’s responsible for filament retraction - not the rotary spool holder.
I was in one of the third-party launch videos, I can’t remember which one.
I can’t imagine why the motors in the AMS lite do not perform the function, maybe I relied too much on the information that purported to be from BL themselves.
There was another reason why the AMS and AMS lite may not be as interchangeable or interoperable as you wish.
The A1 series and AMS Lite have 4-pin sockets and plugs while the AMS units have a 6-pin plug.
The P and X series printers have a 4-pin plug that goes into the buffer or hub with 6-pin sockets.
It will all come down to how they create the hub and power it.
The long and the short of it is:
It is less likely that the existing AMS Lite will be in the mix
Mostly because they have publicly stated it will not be compatible
Given that the A1 series has 4-pin sockets but BL plans to support compatibility of AMS units with 6-pin plug, I’m expecting that the pin difference won’t be an issue.
Everything should become clear once the compatibility update is officially released…
Thank you so much for your replies
Now the adapter hub for A series is out in the real world, and that all ams types except ams lite can be used, will it mean the end is nigh for the ams lite. Since it makes the lite an unnecessary product, as the A series now can fall in line with the rest of the range, using one ams standard for all the printers?
I expect the lite to cease availbilty sometime in 2026
I agree with you, although Im still keeping the slightest hope of BambuLab allowing compatibility in the future.
As an a1 mini owner, I used to have ams lite and was sincerely hoping that ams lite would be compatible with other ams units. But I ended up buying new ams, and retired my old ams lite…
Before I mention why Im keeping a hope, for those who stumble into this topic, I would like to share new information about previous controversies. I queried BambuLab through ticket to verify some misconceptions among users, and here are the summary of them.
Ams Lite’s rotary spool holder IS NOT responsible for filament retraction during automatic filament change. All it does is rewinding the spool for certain angle just to keep the filament from being tangled. The feeder unit of the ams lite actively feed / retracts the filament to / from the tool head.
The biggest difference between ams lite and ams is the intervention of the motor mid-print. Once the filament is loaded into the extruder, ams lite does not provide any feeding power to the filament. Filament feeding is entirely done by the tool head in the process of extrusion.
Whereas, ams provides assistant feed power to the filament with it’s motor. That is why ams requires buffer while ams lite doesn’t. ams pushes the filament to assist the tool head in the process of extrusion.
Now back to the reason for my thought…
If the ams lite’s motor is capable of retraction, wouldn’t it be possible to provide compatibility of ams lite via firmware update by making it function the same as ams? BL’s response to this question was that it’s not due to the “difference of communication signal between them”. Although I do not have full understanding of their device’s technical communication detail, I think this issue is possible to be resolved with OTA update - it’s just out of BL’s priority list.
Unless there’s a clear explanation about the unsolvable technical issue, I would be very disappointed to the BL if they abandon ams lite, since it’s disrespecting ams lite users…
It is both a mechanical issue and a lack of bus power.
The retracted doesn’t go back to the slot, even if it could, there is no mechanism to stop it at each spool motor.
The other AMS units run power in series from AMS to AMS, by a data cable plug from printer, to AMS and then each other AMS in turn.
The AMS lite doesn’t have this option. The A1 series printers have two bus ports, but Bambu has always stated there is no (or will not be) ability to run two AMS units.
About the two ports, that always confused me, why uave two, but then caveat the user that only one ams lite can be used.
I cant believe its a power limit issue, as only one ams at a time needs power. Also with the ota update, more than 4 colours can be used and selected.
I wonder, now the ota upate is done, has anyone tried using 2 AMS Lites ?
