Flow Calibration Clip

I was tired of calibrating the extrusion multiplier for each filament in the slicer. With the flow calibration test attached to each spool I can quickly change the flow factor on the firmware as the print starts so I can switch between spools without reslicing and still have accurate threads, hinges, and holes. Thanks to CK3D and Saphir for the calibration test and clip. Push in the plunger until it stops and see what number it points at. E.g if it stops at -.03 then reduce the flow factor on the printer firmware by 3 when it starts printing, or reduce the extrusion multiplier in the slicer filament settings by .03 to have accurate threads. I found moving the "M221 S95 ; set flow" line in a Prusa printer's starting G-code to before nozzle heating and the bed leveling to be useful; typically it sets flow to 95 after the purge line, so you have to wait until it starts printing before adjusting the flow factor or it will undo your changes. Setting it to 95 earlier in the code means any changes you do will not be undone at the start of the print, so I can adjust flow factor as indicated on the clip while it is still heating and walk away. If you've changed your extruder is a good idea to verify your extruder steps setting is accurate before changing flow factor or extrusion multiplier. I found making two marks 100mm apart on the filament and moving the filament (e.g. the move “axis option” in the “control” menu on a Prusa MINI) 100 mm to work well for checking the extruder steps calibration. In the Prusa MINI menu, adjust “Move E” until the first mark is lined up to an easy reference (like the entrance to the extruder) and exit “Move E” to reset the number to 0. Go back to “Move E” and scroll until the second mark lines up with the reference. Whatever number you get is the percentage the extruder steps needs to be changed to to get it, e.g. my printer needed to be set to 102 on “Move E” before it moved 100mm of filament, and my extruder steps was at 415, so 415 x 102% = 423. Rechecking after showed a command to move 100mm of filament resulted in exactly 100mm of movement.