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Why is the default MK3 firmware extrusion mult at 95%?  

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Punkgeek
(@punkgeek)
Member
Why is the default MK3 firmware extrusion mult at 95%?

Hi ya'll,

So after testing and adjusting my extrusion multiplier for my filament (got about 1.03) I noticed that the default marlin "tune / flow" as shipped from Prusa in the firmware was 95%. Is there any reason I shouldn't just change that to 100% instead of tweaking my extrusion multiplier in slic3r?

It seems to me if I just change the firmware to 100% as the default, that explains almost all of my extrusion multiplier 'error'.

Are those settings persistent in Marlin across reboots?

Posted : 11/08/2018 12:34 am
Kazibole
(@kazibole)
Eminent Member
Re: Why is the default MK3 firmware extrusion mult at 95%?

It’s not built into the firmware, it gets put in the gcode file by Slic3r. Look for the if statement and M221 in the printer profile, custom start gcode.

Posted : 11/08/2018 2:26 am
Eikonic
(@eikonic)
Eminent Member
Re: Why is the default MK3 firmware extrusion mult at 95%?

hmm, thats interesting. i just looked... can you explain that code? if the layer height is 0.05mm, do 100% extrusion, but if its anything else, do 95%... is that correct? since min layer height is set to 0.07, 0.05 can never even be achieved, so is this just some fancy way of saying never use 100% extrusion?

Posted : 11/08/2018 3:58 am
Punkgeek
(@punkgeek)
Member
Topic starter answered:
Re: Why is the default MK3 firmware extrusion mult at 95%?


It’s not built into the firmware, it gets put in the gcode file by Slic3r. Look for the if statement and M221 in the printer profile, custom start gcode.

Oh interesting! - I see it there. Do you have any idea on why Prusa selected this number? Because both the filaments I've tried need an exmult of about 1.03, probably mostly because this 95% modifier.

Posted : 11/08/2018 4:07 am
Kazibole
(@kazibole)
Eminent Member
Re: Why is the default MK3 firmware extrusion mult at 95%?

Do you have any idea on why Prusa selected this number?

I haven’t read the thread completely, but I think it has something to do with: https://shop.prusa3d.com/forum/others-archive--f66/updated-slic3r-pe-over-extrusion-and-cooling-solve-t12949.html

Note that your extrusion multiplier could change for each different type/brand/colour/batch of filament.

Posted : 11/08/2018 4:11 am
Punkgeek
(@punkgeek)
Member
Topic starter answered:
Re: Why is the default MK3 firmware extrusion mult at 95%?

Thanks - that is a good explanation!

Posted : 11/08/2018 4:32 am
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