Chasing correct extrusion width/flow

I’ve been using this calibration set up with Cura for some things

and teaching techs page and methods for others

I could never get the extrusion width to be dead on using the flow methods shown in TT. Really I was only chasing 0.02mm difference here but I was able to get only so close and I was just reading about why that might be. this flow calibration affects everything so I think it’s important.

This is an explanation. pretty long read, but interesting.

Again, I’d like to “like” it, but, like, it won’t let me.