The ProSite protractor made by Starrett (model No. 505A) was invented by trim carpenter Marc Shapiro. He became frustrated on a job installing a large amount of prefinished walnut trim (no room for error like a painted job would allow). After spending many hours jostling a sliding bevel and a small protractor to get readings on angles, and then transferring those angles to his miter saw, Shapiro came up with the idea of a tool that would do both. He worked out some of the kinks with wood prototypes before approaching Starrett to develop and manufacture the tool.

This protractor has two pivoting aluminum arms, 1/4 in. thick by 2-1/2 in. wide by 12 in. long. The tool works beautifully for what it’s designed to do—read and set up miter-saw cuts—and you also can use it for tablesaw setups. The pivoting arms stay put when you’ve moved them into place to take a reading, and the scales have non-glare faces, so they’re easy to read. You can buy the protractor from many woodworking catalogs, local tool-supply stores, and online tool sites for about $40. I’d like to see Starrett come out with a version of this tool that has a scale that doesn’t stop at 90°, so you wouldn’t have to interpolate to get the actual reading of an angle that’s between 90° and 180°.

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