hmmm .. from my experience with steel, acrylic and aluminum ..

the method just differ from one another ...

on steel u have just got to be extra focusing ...

whenever u reach close to the edges ... use a fresh disc and cut slightly more to the excessive side to ensure u have more room to move the disc without breaking it..

after u have make about 2mm more of gap to move around the disc between the cuts. slowly very slow at speed 1, move the cutting disc close by the edge.

with such precision, you won't over cut or break the disc ....