Howdy i just learned how to layout rafter cuts watching you tube and visiting the Swanson Speed Square web pages.
Good to see one carpenters time saving idea was made into a tool most everyone has.

Here is a good laugh i up till now just used mine to mark a straight lines on 2bys. Worse yet my bird mouth cuts were just plain lousy. I mean beyond terrible....

When your done laughing. Have you ever wondered why there is a cut out diamond on those speed squares ? Or worse yet what the little serrated edge was for. Well i never gave it a thought. But let me tell you these are way cool tool improvements. Thank you Swanson an you tube videoers....

Now i can layout rafter cuts including bird mouths that are almost good as a framers. An it is so easy. On Swanson's' web page the Rafter Seat Cuts diagram assumes that the 2 by top rafter cut is to the left. I had to study that for a while to figure it out- i'm left handed wanted to think instead it was to the right.... Imagine laying out a straight line effortlessly- using the serrated edge.

So boys and girls how about sharing your hints for other uses of such a mighty fine tool.