How to use an angle grinder to cut a curve in steel

This was a dilemma I faced when making my weed eater bikes. I needed to make a cutout in the steel mount for the flywheel on the engine. so I came up with this way of cutting a curve. I used the angle grinder to cut into the steel and I made tabs. then I proceeded to break off these tabs and it made a semi circle in the steel, thus, a curve. then you can use the angle grinder to smooth out the edges. this works with thick steel, thin steel, and aluminium. to better understand what I am describing here I recommend you watch my short video.