I have an old Craftsman circular saw with no visible spindle lock. How am I to replace the blade?
Just putting the saw down on some soft wood so the teeth dig in would probably work. Otherwise, stick something in the teeth or a hole in the blade to keep the blade/spindle from turning.
I too had a 7 1/4" Craftsman circular saw with no spindle lock, with a masonry blade that I had trouble removing. It had no teeth or other holes to get a good grip on it.
This procedure worked to remove the blade:
1. Apply some WD-40 to the blade locking nut.
2. Wait a couple minutes, with a few slight taps from a wrench for good luck in to help the lubricant work in.
3. Lock a 10" crescent wrench onto the nut, hold the blade fairly tightly with one hand, and tap on the end of the wrench handle sharply with a hammer to turn the nut and blade counter-clockwise.
The inertia of the blade and motor help to keep the blade still as the hammer's force is applied to loosen the nut.
:You could lower the blade, and install a "C-clamp" carefully, on the blade, positioned to avoid the teeth. Now you can rotate the blade, until the clamp meets the baseplate, and now you have a locked spindle.
With saw unplugged or power removed I just clamp pair of vise grips onto the blade, using the vise grips wedged against the saw or hold it and break the nut loose. Same thing as above avoid the teeth on the blade or it will CUT you!
I'm having problems getting the nut to come out. I've sprayed it with WD-40, I've got the blade clamped down so it won't move. The nut is turning, but it won't come out. I'm baffled as to what is keeping it in.
The shaft from the motor is probably turning also. The nut needs a blow or shock to break it loose. Use a box-end wrench or vise grips on the nut and give a good blow/hit on the wench toward off with the blade locked in wood in a vise or sitting on soft wood.