Hello, recently I've finished a diy Marlin CNC mill that uses a Ramps 1.4 with external stepper drivers. On the z-axis I have a max endstop that pulls the router up to the top. The machine itself works great, but I'm having issues with the software side. I'm using Estlcam (which I really like), but whenever I start a cut, it drives the z axis down to the max z position defined in Marlin. From my understanding (with proper origin settings), it should just start milling without dropping the z axis. I took out all of my start code in Estlcam and nothing changed. So I suspect Marlin might have its own start gcode. Does anybody have any advice on this issue? Thanks for any help.

marlin only does what you tell it to

I would look at your generated gcode. work out what it is doing.

You can run it line by line if needed...