PCB using Snapmaker A350

I am trying to make a PCB using Snapmaker 2.0 A350 on a copper fiber board (copper thickness 2oz, PCB thickness 16mm). I am using a straight groove 0.3mm bit.
I’m having trouble calibrating the machine (i have broken two bits so far while manually setting the work origin .-.)
Also, has anyone used Snapmaker and Luban for pcb printing? The pcb is taking forever to make. I’m testing printing a pcb of 2x2 inches, with two 1x3 headers and a plain routing track and even that is taking more than 4hrs. Not sure what I’m doing wrong
My work speed is 80mm/min
Plunge speed 40mm/min
Step down 0.25
Step over 0.04

Can anyone please help me with this? Can’t quite figure out what I’m doing wrong

There is a writeup in the list about pcb milling - GitHub - shurushetr/awesome-snapmaker: Curated list of things that help you make something awesome with Snapmaker machines.