Finding angle of cutter (chisel, iron, etc.)
I saw an interesting video on trigonometry and thought the technique may be useful to someone here. Of course, it's nothing new, but a quick cheat sheet is always handy. I like it, because it's easy to do if you have one of the many cheap digital calipers available, and a cheap calculator (smart phone will do). In messing around with the numbers, I found that as long as the measurements are reasonably close, the result is very accurate, and easy to remember after one or two times. It would also be easy to determine length required for a specific desired angle.
Here is an example, (without any trig. nomenclature.)
Measure the thickness of the plane blade (or whatever), mine was .070
Then measure the distance from the bevel to the end of the blade, mine was .157
To figure the angle- first number divided by second. Take second number -1.
multiply two results (don't worry about positive or negative numbers). This is the angle.
070/.157 = .446
.446 - 1 = -0.554.
.446 x .554 = .247
If you round to two decimals, it would come to 25 degrees.