Marlin and clay paste extruder (skiping)

Here's the problem I'm having with Marlin and a clay paste extruder .
My geared stepper motor running the extruder pump seems to be giving out when I reach hi steps per mm on the feedrate and or flowrate . The main stepper motors slow down and skip , and the extruder motor skips and hums? This is with no load on the extruder stepper, and the Voltage is set correct.
Here is my setting for the stepper motor drivers and firmware EEPROM

ramps1.4
DRV8825 microstepping
extruder 1/4
motors 1/16
running Marlin (Brad's modification)

It is the current that needs to be set correct. The voltage to the DRV8825 just needs to be high enough. What is the current rating of the stepper motors, and how high do you have the stepper motor current turned up on the DRV8825 boards?

You may have the current set too low on the DRV8825 boards, or set high enough but the boards are not sufficiently well cooled. Or you may have the acceleration set too high in the firmware. Or you may be using high-inductance stepper motors that require a higher supply voltage to the DRV8825 than you are using, to achieve the required current at high stepping rates.

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Large delta printer [miscsolutions.wordpress.com], E3D tool changer, Robotdigg SCARA printer, Crane Quad and Ormerod

Disclosure: I design Duet electronics and work on RepRapFirmware, [duet3d.com].

I followed the manufacturer's recommendations on setting the voltage / current for the DRV 8825. I don't believe it's the fault of the stepper motor or current , I think it's a problem with Marlin not being able to work with high segment speeds. I guess I'll go back to Repetier at least it works with these higher speeds.

You may be hitting maximum step frequency of Marlin for extruder.
By default it is about 40 kHz. Based on your picture you can reach 600x600 = 360 kHz.

I'm still thinking Marlin is weak on the speeds.

printing food