Calculating feedstockMultiplier

[Nathan Porter]

It's pretty clear how it is that we can 'calculate' the filament diameter by directly measuring. Is there any methodology behind the .93 - .97 numbers that I see floating around for this value (or its equivalent setting in other slicers)?

[Dan Newman]

It's a fudge factor, plain and simple. Values around 0.85 are used
for ABS and values around 0.95 for PLA. You'll hear any number of
explanations as to what it is, but at the end of the day just think
of it as a fudge factor.

Dan

[RocketSled]

I'd call it "placebo" more than anything else.  The filament diameter changes all the time, it's very susceptible to environmental factors, temperature and humidity.  The ratio of in-feed vs. extrusion rate changes all the time, too.  I rarely if ever enter the actual filament diameter when slicing.  If the weather has changed a lot since my last print, I often find I have to make an adjustment and reslice something that previously printed fine. Typically, I add a few 100ths. I could adjust the feedstock multiplier but it's easier to just enter 1.81 for a measured diameter of 1.77 if it looks like it's putting out too much plastic on the first couple of layers...