The Bambu Wiki explains how it determines filament remaining - HP_andy has it about right. This works only because Bambu knows the diameter of its spools and wound filament.
Something that could easily measure and add yourself on a filament brand preset…
Wish you would have included HP’s explanation link. Can’t find him anywhere in Wiki.
Okay michael_zanetti - so where in Studio does it show the remaining filament on the spool? I searched and can’t find that figure anywhere, but i do know how much a model will take to produce.
It’s just a few replies up in this thread. You can also see AMS main functions and workflow introduction | Bambu Lab Wiki - the section “Estimation of remaining filament capacity”.
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Well, besides the pictorial view AMS/Studio gives in this picture, I can not find any other mention of how much in ounces, grams or length, AMS gives of a filament on a spool. The picture gives only an approximation, not an exact, which is what is needed to determine if there’s enough material for a particular slicing.
That’s right - it is a very approximate measurement. You’re better off weighing the spool yourself, subtracting the known weight of an empty spool (there are tables with this data for various brands, but keep in mind that manufacturers keep changing their spools.) The AMS detection is good to an eighth of a spool at best, and is also for Bambu spools only.
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@holmes4 posted a link that explains it sort of but it’s actually very simple.
The filament passes through an odometer so the AMS knows how much filament is dispensed.
It uses RFID to gate the odometer. It dispenses filament and starts the clock when it sees the RFID tag and stops the clock when it sees it again.
The odometer tells it in that one revolution how much filament was dispensed - the circumference of the layer of filament on the spool the filament came from.
From that it knows the diameter of filament on the spool which is enough to draw a depiction of the remaining filament on that spool.
There is no weight measurement. It’s just circumference. Anyone who has had to clear filament out of the bottom of an AMS can tell there’s no equipment in there to weigh spools.
Put Bambu RFID tags on other filament spools and they will also report remaining filament.
Yes, but it will likely be incorrect as spool diameters vary.
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Sure, but generally close enough to be in the ball park. Width also matters for how much filament that circumference represents. And so does winding density. Tightly-packed close windings will have more filament to whatever diameter.
My guess would be that it rather uses stepper Motors and with that is able to determine the amount of rotation quite exactly (typically 1.8 degrees of Motor rotation times the gear ratio to the spool) rather than just count full rotations whenever it hits the rfid tag. That would seem too inaccurate to me. Anyhow, it’s not like id know for sure. I could be wrong…
I’d agree with @MZip that with most spools that actually work with the AMS it would be close enough, but one can always respool their filament onto a bambu spool to have the same precision as with a original spool of Bambu Filament if this feature is that important.
I think you are correct that they could use the steppers, but the web page @holmes4 pointed to said odometer for measuring filament payout and the part specifically discussing RFID didn’t say.
It doesn’t really matter to the point of the topic, though. They are very clear they use RFID to know when the spool turns a circle and somehow know the length of filament that was. I tend to believe it’s the odometer since that is a specific function and it becomes redundant if it counts steps.
But either is fine. I was just pointing out it isn’t by weight as some had thought.