In my Marlin config I have the setting :

#define Z_MAX_POS 300

I am extending the Z axis to 400mm temporarily for a print.

Is there a gCode that I can use to change the Z_MAX_POS to 400 without having to reflash the Arduino ?

How can you temporarily grow your printer 100mm?
Why not just set it at 400mm and leave it there.

Hi

Because my Z axis at 300mm fits in my heated enclosure for ABS prints.

Not very often that I want to increase the Z to 400 or 600, so prefer to change it with gCode if possible

There was a gcode defined to set the axis length many years ago (M208), but according to the Gcode wiki at [reprap.org] Marlin uses M208 for a different function.

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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].

Quote
Floyd
How can you temporarily grow your printer 100mm?

it's a home modified i3 design that has makerslides and threadbar on the Z axis that I can change up to the limit of the threadbar ( 900mm )