When sharpening hand planes, it’s important to maintain the correct bevel angle on the plane iron so the tool will work properly. You could buy a reference gauge to check your bevels, but that’s really unnecessary. All you need is a protractor — the adjustable type with moveable legs. I rest the iron between the legs of the protractor and close it up on the bevel edge. With nearly 50 planes in my collection, I need to check angles all the time, and this is a fast and accurate method to inspect every plane iron I own.
– Alejandro Balbis