I’m cutting some half lap joints in the ends of 4x8 beams, so each notch is 3 ½” wide x 3 ¾” deep. I’ve always used my Bigfoot circular saw, made repeated cross cuts using a saw guide then clean up with chisel.
The problem I’m having is the cuts aren’t always square, even after spending ½ an hour setting the saw square! I test for square by cross cutting a 3 ½” wide piece, flipping one piece over and seeing if they both line up where they butt.
Question is, how do you square up a circular saw, and then test for being square?
Is there a better, more accurate way to cut these half laps besides investing in an expensive new power tool? I was (briefly) thinking about putting a 12” blade on my 10” radial arm (if I can find the correct arbor size in a 12” blade) but know this would be plain stupid without a guard!
Your saw blade could be heating up and if so it could distort some while cutting.
I use a tool shaped like a triangle but it's called a "speed square" to check my blade to my saw sole plate. And I check the blade between the teeth because if the speed triangle hits the tooth it will not be square.
With working with power tools and large timbers it may be necessary to still straighten out a joint with a chisel.
