Over-feeding on filament change?
The latest round of firmware seems to have helped - when you get a bad feed, sometimes the printer will automatically initiate a filament change.
This was great till I used TPU's, now I've gotten (a few times) the filament bunched up under the Bondtech's, just before the heat-break.
It looks like an extra cm or so is being jammed in. This makes a little knot, and you can hear the extruder skipping.
Is there something I can do to test this so we can figure out where it is coming from?
You can see the evidence of the over-feeding here on the block:
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Re: Over-feeding on filament change?
A little more observation:
During the filament change, everything is ok. The grinding/overfeeding occurs just after the nozzle returns to the prime tower.
A cm or two is fed rapidly before the priming is started.
This likely is the source of the bulging prime towers (I mentioned, with pictures, elsewhere but there were no comments).
I hope you can see the unneeded extrusion, how it overlaps with the next color, and how that propagates all the way up the tower.
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Re: Over-feeding on filament change?
Not sure how to get a response to this issue, but I think it causes problems.
More pictures - showing the messed up tower.
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Re: Over-feeding on filament change?
A note: I removed the inner PTFE before the filament sensor, and perhaps my settings don't account for this shorter (effective) bowden?
I don't think I changed the "85mm" number, but perhaps this is part of the problem?
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Re: Over-feeding on filament change?
Note: This doesn't happen on user-initiated filament changes, as best I can tell. Only on misfeeds/printer triggered changes.
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Re: Over-feeding on filament change?
Hi,
Thank you, this information helped me a lot.
Now I am getting closer to my first successful MMU print (besides 3 - 5 Layer 30min test prints).
As you can see on the image: on the left side the test prints screwed up due to over feeding on the wipe tower which caused clogging and nozzle crashes and missing layers on the print.
After I changed the setting like you described it was much better (see right side).
Re: Over-feeding on filament change?
Glad to help.
It would be awesome if this could become general knowledge, it sure helped me!
I maintain an informal list of San Diego, CA 3D printing enthusiasts. PM me for details. If you include a contact email and I can add you to the informal mailing list.