Slic3r PE hidden 95% extrusion multiplier
I happened to go into the "Tune" menu on my MK3 today, and noticed that the "Flow" value was set to 95%. Since I didn't set this manually, I was curious where it came from. I started poking through the firmware source code and discovered it can be set with an M221 g-code. I checked the g-code I was printing at the time, and sure enough there was an M221 S95 in there.
Since I had my extrusion multiplier in Slic3r set to 1.0, this was puzzling. I found that the default MK3 profile in the Slic3r PE (I'm using 1.39.2, can't say for other versions) has this in the Start G-code script:
M221 S{if layer_height<0.075}100{else}95{endif}
If I understand things, for any layer height greater than 0.075 (what units?) this is equivalent to multiplying whatever extrusion multiplier you have by 0.95. In other words, if you select an extrusion multiplier of 1.0, your actually getting one that is 0.95.
I'm curious what is the reason for this? It seems counter-intuitive to mess with things this way, effectively hiding the actual extrusion multiplier.
Re: Slic3r PE hidden 95% extrusion multiplier
It is my understanding that the M221 flow rate adjustment is there in the start gcode to compensate for the slight over extrusion that would happen on the mk3's bondtech/v6 combo with any but the most fine layer heights.
This frees up the Slic3r extrusion multiplier setting for it's intended purpose of fine tuning specific brands/colors filaments due to diameter variation, etc.
Re: Slic3r PE hidden 95% extrusion multiplier
It is my understanding that the M221 flow rate adjustment is there in the start gcode to compensate for the slight over extrusion that would happen on the mk3's bondtech/v6 combo with any but the most fine layer heights.
This frees up the Slic3r extrusion multiplier setting for it's intended purpose of fine tuning specific brands/colors filaments due to diameter variation, etc.
Ok, good info. I haven't seen that in the various Simplify profiles floating around, but I guess it would explain why most of them have an extrusion multiplier less than 0.95.