Start g-code: Flow
Hi,
to be honest I didn't notice this until recently when I updated the TFT Firmware of my Sidewinder X2 (which added an info for FLOW). Everytime I printed something with PrusaSlicer, the flow was shown as 95% whereas when I was printing with Cura it was 100% as expected.
In the start g-code of the X2 (actually X1) I found the following:
M221 S{if layer_height<0.075}100{else}95{endif}
In the the start g-code of my MINI I found:
M221 S95 ; set flow
Now to my question: WHY?
Especially the X1/2 one is confusing as it is dynamic. Why doing? OK, Prusa claims the profiles are so well-tuned (that they even don't offer linear advance). But still, why? When I want to adjust my flow, I'm dealing with two places then, the start g-code and the Filament Extrusion Multiplier.
I learned quite a lot while investigating this and certainly do understand a bit more what I'm actually doing 🙂 If now someone could explain to me why this makes sense in the start-code and not "just" in the specific Filemant Extrusion Multiplier section, that would be great.
Thanks!
RE: Start g-code: Flow
See the last paragraph of https://forum.prusa3d.com/forum/original-prusa-i3-mk3s-mk3-assembly-and-first-prints-troubleshooting/life-adjust-z-my-way/paged/44/#post-568036
Mk3S+,SL1S
RE: Start g-code: Flow
Lots of threads in the forum on this, but many of those will lead you here and here. Bob's site has lots of excellent information and is worth book-marking.
My takeaway from Bob's pages is:
- Use the printer front panel to make small adjustments to the filament flow rate during a print if needed. Note: The printer applies the M221 command to make the actual adjustment.
- Unless specifically changed (or the printer power cycled), an applied M221 setting is persistent between prints. Best-practice is to reset M221 to 100% in the startup G-code to avoid filament flow changes from an aborted print causing problems with later prints.
- Remove all other M221 commands from the start G-code.
- Calculate the extrusion multiplier value for each filament type and use it in PrusaSlicer's Filament settings to maximise print quality for each filament type.
With that done, you can be sure that the Extrusion Multiplier value set in PrusaSlicer is actually being applied to your print, and you'll probably also not need to make front-panel adjustments to the filament flow rate in the first place!
Hope that helps!
Cheers,
Tim
RE: Start g-code: Flow
[...] OK, Prusa claims the profiles are so well-tuned (that they even don't offer linear advance).
Linear Advance settings have been present in the Prusa firmware for years now. They recently migrated to LA1.5 in fact. LA values are entered in your filament profiles since the correct value will vary for different filaments. Look at the custom start gcode under filament settings.
and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan
RE: Start g-code: Flow
@bobstro Just wanted to say that your 'Project Notebook' site is a fantastic learning resource! I'm quite new to the world of 3D printing (just 3 months under my belt) but it has really helped me flatten the learning curve.
Cheers,
Tim
RE: Start g-code: Flow
@bobstro Just wanted to say that your 'Project Notebook' site is a fantastic learning resource! I'm quite new to the world of 3D printing (just 3 months under my belt) but it has really helped me flatten the learning curve.
There are so many easily forgotten little nuggets of information with this endeavor that I wanted to capture some of it. Glad the notes are useful. Thanks, Tim.
and miscellaneous other tech projects
He is intelligent, but not experienced. His pattern indicates two dimensional thinking. -- Spock in Star Trek: The Wrath of Khan
RE: Start g-code: Flow
[...] OK, Prusa claims the profiles are so well-tuned (that they even don't offer linear advance).
Linear Advance settings have been present in the Prusa firmware for years now. They recently migrated to LA1.5 in fact. LA values are entered in your filament profiles since the correct value will vary for different filaments. Look at the custom start gcode under filament settings.
As I wanted to proof my point I once again read the statement from the help pages. You are right - I got it wrong.
"Print profiles for the Original Prusa MINI are well-tuned. Additionally, there has never been LA1.0 on the MINI, so no conversion (to LA1.5) is required."
Thanks to all the other answers. I'll check the provided links later today