Hi,
Can someone help me: I’d like the filament retracted after a printingjob. That way i can easaly change the filament after the hot end has cooled down, the next morning.
Is it possible to have a command in the G-endcode to do this before switching the heating off.
The same is after restarting the printer, how can i change the G-startcode to extract the filament by the same length before the printing starts?
Thanks. I hope someone can help me.
Duskey,
It is possible to do this.
When you go to slicer and go to the tab Printer Settings and then go to Custom G-code u find the line “G1 E10 F400;”
Just copy it to beginning of the End G-code textbox en play with the E and F values as you wishes.
Best Regards
VEL760
Hi duskey and VEL760,
there’s a bit more to that than just playing with the settings.
While the retract speed seems a good point to start with, it’s worth noting that with the default settings in firmware etc. the extruder is pretty much maxed out at that point. Retract is 65 mm/s (so in a G1 command, this would then be F3900 due to the conversion to mm/min), and 66.67 mm/s is the limit.
For a rather long “retract” like you want to do, a lower feedrate should also work, maybe half that much or even lower. The critical point is that, during printing, there’s a plug of half-molten filament in the hotend. Since the inner diameter of the hotend is a bit wider than 3 mm, this plug is wider, too. When you pull out the filament too slow, the plug solidifies in the PTFE tube and the filament gets stuck. Pulling too fast can also be bad due to the high forces exerted on the filament.
At least one part of this is rather easy. The (printing) G-code usually ends with G92 E0, so at least the reference point for the G1 command is set. Nevertheless, it won’t hurt to double it, just to be on the safe side.
All in all, I would only do this retract automatically if I knew the parameters for my filament very, very well. Otherwise the risk that the extruder damages itself (or the filament) would be too high, at least for my taste.
That holds even more for an automatic reverse move at the beginning of a print. You never know for sure whether the filament is at the position that it should be. Slip on the transport screw is a common error, and if you change the filament, you won’t know either whether it’s exactly as far in as it was before. Therefore, some fixed, perhaps even fast movement at that point is asking for trouble.
Cheers,
kuraasu
Hi Kurasuu,
Thans for your explanation. I think the best is to forget this idea, to preventie problems with the filament. IT is clear to me what the problems could be.
Greetings, Chris.