Nice thinking. My circular saw has a small bolt. I think i need M8 but i will keep looking.My sliding compound mitre saw, circular saw and one of my cold saws have Left Hand M10 bolts holding the blades on.
I stock 2 metres of A4 stainless M10 and BZP M12 left hand threaded bar and keep a set of M6, M8, M10 & M12 left hand taps and dies.