Many years ago my carpenter square mysteriously disappeared at the start of my basement finishing project. So I started using a butt hinge to mark lumber. It worked better than I had hoped. My carpenter square is still hiding from me, but I still use a 31⁄2″ x 31⁄2″ full-mortise butt hinge for transferring my layout marks for trim work.
The real advantage of using a hinge is that it allows you to bring lines around corners, such as when you’re marking out a tenon, with minimum error. When choosing a hinge for this purpose, select one without a finial (which will get in the way of your line) and one without a lot of slop between the leaves and the hinge pin. The tighter the hinge, the more accurate your layout lines will ultimately be.
– Milo Meyers
If you’re interested in learning more tricks like this one, check out “601 Woodshop Tips and Tricks.”