Extrusion Multiplier vs Changing Esteps

[zerb]

when trying to dial settings in say for example you get your esteps setup at 800. you then print some test pieces and determine that you needed to set the extrusion multiplier to .90 to get everything to look proper. is it best to leave that extrusion multiplier at .90 for that specific roll of filament? or can you do some math and just go ahead and change the esteps in the firmware on the machine?

example. esteps @ 800, extrusion multiplier @ .90
would that then mean youre putting the same amount of plastic through the nozzle as you would be if you were printing with the esteps @ 720 (90% of 800) or is that math incorrect? or should it be 800 - (.90% of 800) = 792.8?

[CompoundCarl]

You should be able to adjust either one - they should have the same affect.

But personally, I always just set the E-steps-per-mm value in the firmware to the actual mechanical gearing ratio for the printer. So it's something I can determine just from the hardware on my printer, not via experimentation (for example, if you know the number of stepper steps per revolution including microstepping and filament drive gear diameter, it's pretty easy to calculate).

Then I change the software's flow adjustments to dial things perfectly

[zerb]

do you recommend doing it that way, knowing the steps of the motor and doing the math, versus doing the method that ive been doing...which is measure 100mm of filament, tell the software to extrude 100mm, see what you get, change esteps accordingly until printer extrudes exactly 100mm?

[CompoundCarl]

Again, I personally always set the E-steps/mm in the firmware by doing the math.