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Newbie alert...
On my Ender-5, when I go into the "Tune" menu during a print and adjust the "Speed" value, that value will later be shown in the display next to a label saying "FR". I can also adjust that value by simply turning the knob during printing (and thus started to think of it as the "speed dial" ;) ).

As far as I was able to tell so far, the "FR" percentage value is being applied to all four stepper motor movements and thus allows me to slow down or speed up printing on-the-fly, e.g. to make up for sub-optimal speed settings chosen during slicing (after all, I'm still learning).

I only recently learned that FR is actually short for "Flow Rate" (or is it "Feed Rate"?) and that seems to imply that this is probably about more than just motor speed... Also, there seems to be no equivalent to the Speed setting in Octoprint: All I have on the Control tab are two distinct sliders for "Feedrate" and "Flowrate". Would I always have to move both to achieve the same effect?

Can anyone clarify? What implications of changing FR/Speed might I be missing?

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By turning the knob in the main screen, you're adjusting "feed rate". This is essentially a factor that all g-code speed settings are multiplied with - "speed dial" seems an appropriate name for it.

"Flow rate" is something different altogether - this is multiplied with the extrusion commands. It has the same effect as changing your extruders steps-per-mm. You can adjust under- / overextrusion with this on the fly.

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  • $\begingroup$ OK, thanks! But don't extrusion commands also include "g-code speed settings"? When I'm moving the axes faster, the extruder also has to adjust its speed accordingly just to keep up, right? So, would it then be correct to say that Flow Rate is applied "on top of" the Feed Rate but only affects the extruder motor? $\endgroup$
    – Oliver Giesen
    Commented Jul 8, 2019 at 15:08
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    $\begingroup$ @OliverGiesen 'Speed' affects how quickly, 'flow' affects how far. Flow rate is like a dimension scaling, but only for the E axis. $\endgroup$
    – Sean Houlihane
    Commented Jul 8, 2019 at 16:02
  • $\begingroup$ feed rate is used in some slicers for the material feed rate You mean code processing rate, right? $\endgroup$
    – Trish
    Commented Nov 6, 2020 at 9:59
  • $\begingroup$ @Trish I've never heard of code processing rate. That sounds like it should be affected by buffer sizes and serial connection speeds, not F tags and tunable menu items. Do you know which slicers call flow rate that? The flow and feed rate terms have been pretty clearly "standardized", I don't like the "feed rate" term either, but it's a silly remnant from CNC mill days, just like the mm/min unit - but I think it's too late to get rid of those definitions now. I'd probably prefer "speed" and "flow" if it were up to me. $\endgroup$
    – towe
    Commented Nov 6, 2020 at 10:14

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