I have a Skilsaw 5250 7 1/4" circular saw i picked up used 20 years ago. No idea how old it is, but still works.
I recently put a metal grinding blade on it to cut roofing tin. Worked great. But now I want to put the saw blade back on. Never saw a blade lock button, so always used a Phillips screwdriver through one of the holes in blade to "lock" it while tightening/un-tightening the blade nut.
The metal grinding blade has no such holes. I Can't find a way to secure the blade/spindle while trying to loosen the nut.