I've just cut a 5mm x 2.5mm keyway in an aluminium pulley.
Now' s a good time to ask the right way to do this!
I brazed a piece of HSS into a piece of bar stock, mounted it in the mill chuck and then took small bites until done. The reason for asking is that I want to repeat the trick but the next pulley is cast iron - wouldn't mind some advice before proceeding -
A secondary question is that when I brazed the HSS into the bar, the cutting edge was just about "blue" as the joint was made. Next job is to braze a die chaser into a piece of square bar (I'm told a better device than a single point tool) and don't want to ruin the cutting edges.
TIA
Steve