Feedrate/Flowrate and steps per unit

Hello,
I have some questions related to software

1. I am trying to understand this variables:

#define DEFAULT_AXIS_STEPS_PER_UNIT   { 80, 80, 4000, 100 }

and

#define DEFAULT_MAX_FEEDRATE          { 200, 200, 2, 20 }

Are they releated with each other?
I am asking only about extrusion params

2. I am using Slic3r and does "Extrusion multiplier" change steps/mm (so modify var DEFAULT_AXIS_STEPS_PER_UNIT )?

3. What should i do if i have to print PLA in 230 deegrees and having underextruded elements?

Thanks

1. No. Well, not really. Something with a large number of steps/mm is probably going to have difficulty going really fast, since there's a limit on how quickly the board can send pulses to the stepper driver, and chances are that we also have to give the motor time to actually obey the commanded pulses.

2. No, it's more accurate to say that it changes the commanded number of millimeters extruded So if you set a multiplier of 2 and it thinks that you need to extrude 10mm, it will instead command the machine to extrude 20. This will still obey the max feedrate setting, so it would need twice as long to complete the extrusion if it would be maxing out .

3. If it's consistent, then chances are that you have some parameters set incorrectly. This can be if you are using volumetric extrusion, and the filament width in the firmware is different in the slicer than it is in the firmware. (Marlin defaults to 3mm filament, which seems less common than it used to be.) It can also be filament consistently thinner than nominal, or it can be a number of other things. A misconfigured thermistor can report incorrect temperatures, and you might not be hot enough to get good flow. Your nozzle could be blocked, your heat break could be too hot. If you are actually extruding the amount of filament that you think that you are.

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3. It could be anything. To home in on the problem, document the problem and post a new topic describing the problem, 3d printer, configuration and slicer settings.

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Kind regards
Imqqmi

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