For most tasks on the machine, the machine coordinates aren't really important, you're usually only concerned with the work coordinate system (via the Set X/Y/Z buttons in the UI or a command like G10 L20 X0 Y0 Z0 (sets the current position as 0,0,0 in the work coordinate system)) - but I also often find it annoying to work with negative coordinates when first setting up a job, so I'll sometimes run G10 L2 X0 Y0 after homing - this will set the work x and y to the absolute machine coordinates, so the front left corner of the machine is 0,0 in your work coordinate system. (Note that you probably don't want to include Z0 in the G10 command - as will set z=0 to the very bottom of the z axis.) ---- To try to answer the actual question, even though I don't think it's advisable and I haven't tried these myself: if you really wanted to invert your axes and make the home coordinates into machine 0,0, you'd have to at least make these changes (1) flip the motor direction in config-drives.g (2) change the endstops...
I did see that most posted numbers for RPM on the workbee are much higher than expected - the cutter I’m using has a recommended chip load of .12mm, which results in a theoretical rpm of ~8300 at 2000mm/min - I already reduced the chip load to 0.08mm to account for the fact that the workbee isn’t the most rigid machine, but 18k would mean a chip load of 0.05mm, which to me sounds like getting close to the tool just rubbing - but maybe my expectations are off here, I’m still quite new to this! If you have some guidelines on how far you generally derate endmills for the workbee, it’d be quite useful to know! The cut depth is an interesting one though - i didn’t think 3mm with a 6mm endmill would be pushing it, but I’ll try with a gentler finishing pass and see if that makes a difference!