DO NOT trust your AMS

you dont need to do any of whatever over complicated gibberish that is. Just make sure the slicer and AMS material types jive. Which I did. On the “send to print screen” you select which slot to use. The AMS did not pull from slot 3 as I commanded.

My AMS also doesn’t always follow the filament I chose in the slicer. I sometimes have to correct the program in the ‘send print’ dialogue box. This is super annoying. It usually happens when I print in a single color.

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Did it for me a few times too during calibration I manually started. I thought I was tripping.

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I’ve always done it the way @danmcm suggested above and not tried the way the OP has suggested.
I’ve never had an issue with the AMS picking the wrong filament this way.

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Same! And I have two AMSs.

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Same here, Possible Bug - AMS Filament Descriptions - #5 by duane777

Same exact thing happened to me. I have a car part I’ve printed hundred of times, always on the first spool (black asa). The other night, it printed the whole thing from spool #3 (blue abs). I know for sure #1 was selected in Studio. It happened once before and I thought I was crazy, but this time no question in my mind it printed from #3 despite slicing it with #1 selected in Bambu. It was still on the screen when I woke up to blue parts.

I have had this happen, too, but not consistently. I generally run pairs of filaments so that I can run each roll to the end. I try to make sure that every job starts on the partially used roll so I don’t end up with two partials and end up having to be there to manually load a new roll during a job.

The system does what I tell it to most of the time, but there have definitely been more than a couple of times where it did not.

I think we’ll notch this one up to user error. Check twice, print once.

You can check the gcode to see exactly what slot it was told to use.

How do you do this? …

If you open the gcode in notepad++ or something similar then you can search for the “T” gcode. In the example below, you can see it as T2. This means that it is using the 3rd filament slot, T0 being the first one.

M620 S2A ; switch material if AMS exist
M109 S220
G1 X120 F12000

G1 X20 Y50 F12000
G1 Y-3
G1 X54 F12000
G1 Y265

M621 S2A


I usually load the filament that I want to use if I am unsure if it will pick the proper one.

This way when I go-to print if it unload say slot three and tries for one I know something is screwy

I know, this is why I said I do it this way so I know that it is selected in prepare and under device I make sure it matches. This way I am assured it works

Mine started using the wrong spool right in the middle of a print. Now it constantly unloads back to the ams and requires me to push retry every time.

This is what we call a PICNIC.

Computer (or AMS in this case)

User error bud.

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you got me mr big IQ. you so smert. i big dum. i smacsh keyboard it no print. waaaaaa. thank you.


Not unexpected.

obviously no one is as smart as you. You are gods gift to humanity. how do you handle being so important. you deserve to take over for musk and bezos. i cant believe they would deny your greatness.

Glad you recognize my greatness.

You’re still triggered. That’s unfortunate.