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Custom G-code for filament change  

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meltdown
(@meltdown)
Active Member
Custom G-code for filament change

I'm trying to do a print with a color change on the very last layer (essentially, trying to simulate a two-color solid), essentially a white cube with a black dot on the top face. I've been trying various forms of filament change and avoid getting leftover extrusion in the new layer (which is very visible when using black and white!) I tried the PrusaSlicer filament change G-code:

M600
G1 E0.4 F1500

After the filament change, I pull away any excess material. Unfortunately, there somehow seems to be a little "loop" of the new extruded plastic hanging by the time the next (final) layer is started, causing some visible quality issues.

I've tried using just a M600, but still seem to have the same issue. I'd like to add a little custom G-code to fix the issue, and my two ideas are:

  1. Filament retraction (which I have not used before, and I'm not sure if it would cause the start of the layer to go missing)
  2. Adding a second copy of the intro line (which is complicated, because I need to change the Z to and back) to clear out any issues

Do these approaches make sense, or is there a better way to do things?

Posted : 19/12/2022 1:08 am
JoanTabb
(@joantabb)
Veteran Member Moderator
RE: Custom G-code for filament change

why complicate matters... 

print the white, 
do the standard colour change option, 
when the printer does the colourchange, resist the temptation to pull the waste off the nozzle, 
the printer will ask if the colour is clear, respond NO. 

the printer will extrude more of the new colour, 

when you are happy that the first colour has been purged from the nozzle, resist the temptation to pull the waste off the nozzle. 

Instead, trap the waste pile against the build plate then choose YES, to say thefilament is running clear new colour, at this point the printer will move the extruder back towards the print and all of the waste material, including the last annoying squirt, will remain attached to the waste pile that you are holding in position with your finger... 

regards Joan 

I try to make safe suggestions,You should understand the context and ensure you are happy that they are safe before attempting to apply my suggestions, what you do, is YOUR responsibility. Location Halifax UK

Posted : 19/12/2022 1:29 am
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