I’ve been printing quite a few dual-color models lately. I have an AMS attached to both left and right nozzles, so that spools can be swapped without manual intervention especially over the night.
Once a spool is consumed, if a nozzle change is needed, the printer will fully purge the filament in the PTFE tube (~30cm in my case) then continue with the nozzle swap. To me, this is completely unnecessary and leads to wasting filament, time and energy.
The ideal behavior would be to swap nozzles remembering what is in the “consumed” one - pretend the spool is not over, if you want . If that nozzle requires a color change, if the printer suffers a power outage, if the print is stopped/interrupted/completed, then yes, purge by all means. However, if the same filament is needed, continue using it until it’s really done, as would happen without the color change.
What do you think? Did anybody else observe this behavior? It’s been driving me crazy over the last few weeks
Thank you for the feedback. Not knowing the underlying details, I didn’t realize it was difficult to implement. Thank you for sharing
Worst case scenario, I’d even consider a checkbox for power users with “use at your own risk” disclaimer or accepting this configuration only when there are identical filaments in the AMS - or other limitations that make sense and could make it easier to implement.
If the filament runout is detected at the AMS’ filament bay’s throat, there is a physical-reality problem to trying to rewind - if it spits it back out, this is now going to be a big ball of tangled spaghetti emitted into the ams bay - the rollers wont respool what isn’t atatched to a spool!
The software would need to read-ahead and determine that there are no more swaps in the next 10 grams (example) but the precision is questionable - the slicer doesnt know what length of your PTFE tube…
The point is valid.
I am wondering if the simple solution would be different: if filament runout is detected at the AMS’s filament bay’s throat and a nozzle change is needed, just remember current filament bay in use.
This way, when changing back the nozzle, if the bay in use corresponds to the correct filament, continue printing. For any other scenario, purge first.
I just had a print where I finished out a spool and it automatically switched to the next. I was curious as to how it would handle it so I watched. It used ALL of the old filament until it tripped the sensor inside the print head. It only purged that last tiny bit after it fed the new stuff in.
It becomes a different scenario when the last bit of filament has just left the AMS feeder and a color/filament switch is requested.
Then all the filament in the PTFE tube will be purged.
Exactly this. And it would be ok in general, but it becomes particularly time consuming for dual color prints with changes on each layer because only a small amount of filament is used on each layer (so it uses a few mm of filament, and it purges the entire PTFE if the run-out sensor is tripped off)
. If that nozzle requires a color change, if the printer suffers a power outage, if the print is stopped/interrupted/completed, then yes, purge by all means. However, if the same filament is needed, continue using it until it’s really done, as would happen without the color change.