"The flow rate has this not be changed" (Feedrate and Flowrate under Manual Control)

macelius

Hi All,
So the line above (taken from the Feedrate help bubble) continues to confuse and confound Me, the previous line says "All speeds are multiplied by this value", so is flowrate automatically increased proportionally as I increase the feedrate, or do I have to increase the flowrate to match the feedrate manually to avoid under-extrusion?  

I found this thread, that seems to suggest so: http://www.soliforum.com/topic/1028/feedrate-flowrate-and-adjustment-of-both/
"I experimented with these settings in Repetier-Host (so this is not really the same as knowing).....Running calibration boxes, I found that an increase to 200% feedrate required about a setting of 109% of Flowrate in order to maintain a calibrated single thread wall of .42, all else staying the same."

Please advise.
Thanks!
~Mac

Repetier

Extrusion is coupled to move distance not speed, so faster moves will extrude more. and no flow adjustment is required  At higher speeds you might get mor slippage or need higher temperatures to keep ratio physically, so flow increase may be required to keep up with new speed, but only if you exceed limits. Also at higher speeds effects like acceleration have more influnce causing non proportional changes.

macelius

I see, I got You, thanks for the clarification.  So it sounds like If anything one might need to increase the print temperature at higher speeds first to help the filament melt during the time it's passing through the nozzle and make it a little easier on the extruder.

Repetier

Yes, after all it needs to get to extrusion temperature at the end and if you print faster heating time is shorter. At some point this might be too short for fast extrusion.