Here are a few steps that should help you calibrate your extruder.
With 1.75mm Filament you want to use about 90mm per minute. With 3mm filament you want to use 30mm per minute.With 1.75mm Filament you want to use about 90mm per minute. With 3mm filament you want to use 30mm per minute.
1. Mark your filament at 150mm above your extruder. You can use any point of reference as long as it does not change. Something you can always reference again.
2. Using the interface of choice Pronterface, Octoprint, etc.. Send the following codes.
A. G92E0 (Resets the extruder)
B. G1E100F90 (Use F30 for 3mm Filament)
3. Once it has finished extruding, measure from your control point to the mark you made earlier. (If you can no longer see this mark, there is a major problem.)
4. If you do not currently know your steps per mm of the extruder, issue a M503 command. You are looking for something like: Recv: EPR:3 200 95 Extr.1 steps per mm (Yours may be different depending on the model of printer.) EDIT: My Prusa MK2.5 shows:
Recv: echo:Steps per unit:
Recv: echo: M92 X100.00 Y100.00 Z400.00 E133.00
5. Use this number to plug in the variables in the following formula;
New Steps/mm = (Old/Current steps/mm) x [100 / (measured distance filament traveled)]
Ex: Our A8 had an old steps/mm of 95 and we extruded 97.09mm
So 95x(100 / 97.09)
100/97.09 = 0.9709
95 X 0.9709 = 92.2355 <- New Steps/mm
6. Now issue a M92 E<NEW STEPS/MM> (So for us it is M92 E92.236)
7. Now issue a M500 to record to the firmware.