Mitre cuts...what am I doing wrong?

[wdfifteen]

Actually it looks good to me, given the quality of the wood. Doing rough work like that I lay the brace to be cut in place on the “square” corner and mark the cut lines it against the square sides. You don’t need no stinkin square.
When the carpenters were framing my room addition 10 years ago a worker was up in the rafters measuring the pieces he needed and the boss was on the ground cutting them. The worker yelled down, “Twenty-four and an eighth.” The boss yelled back,”This is framing! Ain’t no such thing as an eighth!”

[juanbenae]

Originally Posted by wdfifteen

Actually it looks good to me, given the quality of the wood. Doing rough work like that I lay the brace to be cut in place on the “square” corner and mark the cut lines it against the square sides. You don’t need no stinkin square.
When the carpenters were framing my room addition 10 years ago a worker was up in the rafters measuring the pieces he needed and the boss was on the ground cutting them. The worker yelled down, “Twenty-four and an eighth.” The boss yelled back,”This is framing! Ain’t no such thing as an eighth!”

Ya, I was the guy down on the ground cutting after I was a seasoned carpenter. Rarely actually measured for every rafter. Took the room dimension, slope of the roof, set the ridge based on that and the rafter seat cut (also referred to as the "birds mouth"). Cut one for each side, when they fit, I cut the rest them as fast as the two guys up top could set and tack them in place.

On a hip or valley, you would use the room dimension, get the length, see a speed square Hip/Valley & notice it's different than a common rafter/jack for the plumb and seat angle. A hip/valley has to be longer and have a different plumb cut than a common rafter cause it's generally running at a 45* angle. Once the hip/valley is set a rafter book will tell you how much to add or subtract from each "jack" rafter based on layout spacing, 16" or 24" generally. You always wanted to set a left, then an opposing right rafter as to not push the hip/valley out and bow it. The jack rafters landing on a hip or valley take the same plumb cut as a common rafter.

I was not good enough to cut an entire roof with just dimensions & slope, I would test fit pieces before I went to cutting all the common or hip/valley "jack" rafters. I worked for a guy who would do just that, cut an entire roof with a set of plans, a rafter book, a calculator, a framing square with stair stops, a unit of lumber and a skill saw.

He was a witch!

[gregpark]

I'd cut the piece an inch long, hold it against the face of the framing where it's it going with my speed square lining up the 45° and pencil mark both sides of both ends to be cut. Id use my chop saw and line up my marks by eye but a table saw will work.