“Simply retract 20mm to 30mm of filament just before cutting.”
Hello, It seems that it should be fairly easy to reduce the amount of filament lost through purging by 50% to 75%. Just retract 20mm to 30mm of filament just before cutting.
Thank-you in advance.
There’s about 42 mm of filament in the head, about half in the hot side and half in the cold side. It should be possible to remove at least 20 mm of cold filament without deformation. And perhaps a little more, depending on the filament’s heat behavior. If part of the hot filament is only slightly stretched, it can be retracted too. This depends on the filament and the temperature, but should be no problem for at least the cold 2 cm.
Well, not exactly. The cutter currently still leaves about 4.5 cm of old filament in the head. The printer therefore need to remove 4.5 cm of the old filament and replace it with the new one. If you retract 2 or 3 cm of filament from the head ==before cutting== there’s only 1.5 to 2.5 cm of the old filament left to extract before you have a clean head. I suggest retracting 2 to 3 cm of filament ==before== cutting. And so, where it took, say, “200” to purge cleanly, it will now only take “50” or “100” to purge just as cleanly, because there’s less of the old filament left in the head. This is just a very simple add in the gcode before each cutting.
From what I understand it’s important to get a clean cut of the filament and not a pointy stringy tip which happens if the filament is completely pulled out of the hot-end. So one probably has to play with the amount of retraction to get most of the filament out but not all. That’s presumably what you achieve by retracting 2-3cm. Smart idea overall!
Yes, exactly. There’s about 42 mm of filament in the head, about half in the hot side and half in the cold side. It should be possible to remove at least 20 mm of cold filament without deformation. And perhaps a little more, depending on the filament’s heat behavior. If part of the hot filament is only slightly stretched, it can be retracted too. This depends on the filament and the temperature, but should be no problem for at least the cold 2 cm.
Just ordered my printer yesterday and have been doing a lot of research. I was actually thinking this exact same thing. I can understand why they would not want to do it by default because of the risk of clogging, but if it could save me half of the waist at least then I am all for trying it out.