Upon start of print - flow jumps to 95%

edited November 2020 in Bug Reports
I discovered a strange bug (or have set up something wrong)...

I slice in PrusaSlicer and copy file to SD-card, start a print and everything works fine. I can see the same temperatures and flow as set up on the printer in repetier-server. I then take the same file and send it to the printer (Prusa i3 MK3S) via "Direktdruck" and after the prime line is printed the flow automatically jumps from 100% to 95% (on GUI, the printer and LCD)... If I abort the print, set flow to 100% and send file again - same procedure.

Did I miss a setting or why is this happening? A bug?


  • Not a bug - it is the prusa slicer config you use. For some layer heights they add M221 S95 to the gcode which is exactly what you see then in server. Since that was their intend you should leave that also I'm not so happy that they use a switch meant for users to later adjust flow to fix a volume problem in their solution. They should instead reduce multiplier, but it is like it is. So that is why you see it.
  • edited November 2020
    Ok, so basically that is an internal Prusa thing? That's somehow weird. While (almost) every data from the printer shows up in server even when a print is started from SD-card, the 95% flow-thing is just visible in the printers menu (tune -> flow). The server still shows 100% but bed-temp and nozzle-temp are both live printer data.

    So is the flow really 95% of whatever value I set up before? I calibrate my filaments using the extrusion multiplier... is that the 95% value? Strange...
  • Ok, started looking around for the Prusa 95% flow-thing on the net and found many answers.

    Just one thing... when printing from SD the web-GUI doesn't reflect the 95% change. That would be great to have so no one gets confused.
  • Problem is we do not see commands send from sd card. So without a message telling us new value we don't know it changed. That is also why you should send everything through repetier-server directly so we know the state. But most important even if we show wrong value from this firmware is using latest value correctly.
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