I have a mid-to-late 1970's model 7 1/4" Craftsman circular saw and was having trouble changing blades to do some plywood sawing. Lo and behold...others had had this same problem. Bless the internet!!
Anyway tried one of the suggestions and it worked...got the nut off w/o much of a problem. Changed blades and realized that all of the blades that I have have either holes or lengthened notches in them in just a few places and if you place a screwdriver in the notches and brace it against the housing the nut comes off easily and also goes back on and tightens down the same way.
Blades are from the same decade as the saw... All are in great shape...glad to hear I have one of the better made, though heavy, circ.
saws. Going to use it tomorrow...
Never ceases to amaze when I can find an answer to the most obscure question. Thank you for having the foresight to consider this could be a problem for some and then posting a comprehensive question and reply. I can't wait to see the look on husbands face when he wakes up to find I have removed blade for him. I bought the saw for myself in the early 80's long before we met. Hahaha. Healthy competition going, it's all good. Thanks again!