Purge/Waste filament when run out of ams

Bambu Lab AMS AMS 2 Pro
1

Hello,
I had a 20h print and after 5h the filament runs out. A new spool was ready and I stand next to the printer.
When it runs out of my ams, the h2d purge the complete PTFE for more than 5min… Why?? After this I can add the new spool and resume print…

Complete waste of filament and time. Why it don’t print to the extruder sensor?

Bye
Andy

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2

Normally this is how it happens if your print is a single filament.

I’m not sure how your 20 hour print was set up but if it had more than one colour this is probably normal behavior. What’s happening is that once the filament end feeds past the first stage feeder in the AMS it has no way of being retracted. If there is a call for a filament change during this time the printer has to purge all of the filament in the tube out instead of retracting it.

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I printed with my h2d. Red pla for the model on the left. PETG for the support on the right. No need for change the filament from this nozzle.

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4

I just ran into this as well, total waste of filament! Surely there is a software fix for this. I was doing a two colour print, only one colour coming from that AMS. There would be no need to do any retractions from that ams till the end of the print.

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5

It cannot retract anymore once the tail end leaves the gear system of the AMS. At the end of the print, you’d have to go rescue the printer manually if the extruder cuts and pulls back for the next job - it would have a piece of filament stranded in PTFE not contacting any gears. The logic to determine if theres enough left to finish the print depends on your PTFE length. Shaky. I guess it could like store a flag and invoke the purge at the very end, if there was enough filament to finish. But it’s gotta go, or you’re fishing spaghetti out of PTFE with your hands.

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