@Whitewold:
Make sure your slicer is configured for relative extrusion and not absolute…. M83 in your slicer start gcode if it doesnt have a check box like S3D does.... if its Cura then you will need to set M82 for absolute mode in config.g instead of M83
Once done change your steps back to 800 and retest then do the formula again
I did the extrusion test using the Duet console, but I'm glad you mentioned slicers, because I don't know how to set up a slicer for the Duet. I've been using Cura for my Marlin/MKS set up so far and it has been going well. Is there a set of instructions for using Cura in conjunction with the DuetWiFi?
I actually tried printing a test cube with the Duet console and it started printing a baseless, hollow test cube, and smeared filament all over the area, like a fire hose.
@MiR:
You may also want to check extrusion speed in the web interface of duet, before extruding hit the button for lowest extrusion speed or the one with 2nd lowest speed.
As you describe it you perhaps were using a too high extrusion speed.
I believe the extrusion speed was set to the default 100%. I'm not sure if that means it represents my max extrusion setting or not.