Taken from http://josefprusa.cz/skeinforge-40-volumetric-calibration (Thanks Josef Prusa)
In this article I want to help you with SF40 calibration.
Main difference over older version is volumetric flowrate.
It basically means that SF counts how much of the plastic its should extrude for given layer height and width of trace (height*width*lenght = volume).
Most confusing on all this is to realize SF uses the length of filament which goes in instead of extruded thread which goes out. For that you need to set your e_steps_per_mm in your Firmware to count with filament instead of extruded thread. And I'll show you how.
Tools you need:
- Some permanent marker which can make visible marks on your filament
- My RepRap calculator http://calculator.josefprusa.cz/#ExtrusionSF40
So how to do it?!