prop pitch bmeasurements

I have several propellors from 12" to 18" and would like to know their pitch. Is there a simple task to find pitch
First time user so be gentle

 

From Dave Gerr's book:

With the prop face up on a flat surface, find the point along the blade that a 45-45-90 degree triangle will best fit the angle of the blade. Measure this point to the shaft centre line. This is radius "R". Pitch = R x 2 x 3.14

I've tried this, and found it quite difficult to be accurate because of the shape of the blade I was working on. I measured my blades at about 14.5". I took them to a prop shop, where the technician measured them at 13.5".

My advice, take them to a prop shop for an accurate measurment, my local guy did it for a box of beer.

Robert