Trim carpenters are inevitably faced with needing to measure accurately from the short point on a mitered piece of trim. Problem is, the tape measure’s hook can’t get a purchase on the short-point corner. The drawing shows a fixture that I use to help me get quick, accurate short-point measurements every time.
I start with a sheet of plywood, some lengths of 1x and a couple of 12-in. long pieces of the trim that I’m installing. I cut 45° miters on the two pieces of trim, being careful to make the cuts the opposite of what I’d do for a piece of trim; the inside edge of the trim becomes the outside edge for these two pieces. Next, I make a 90° cut on the end of a 1x block. As shown in the drawing, these three pieces are arranged so that the long points of the 12-in. trim pieces are aligned exactly with the end of the block.
I use my nailer to affix these pieces to the plywood table. Then I nail on a couple of 1x fences to keep the workpieces aligned correctly. This all takes about ten minutes to build.
To use, cut a 45° miter on the casing you’re about to install, leaving it a bit longer than necessary. Insert the casing into the appropriate slot, and butt your tape against the square-cut block in the middle to pull the measurement.
Bill Pinkham, Richmond, CA