The use is immediate: just place a punch with the tip on the bottom corner to see if a certain bend is feasible with that tool. This is the same technique that has always been used in fabrication to analyse the bending sequence; the advantage is that instead of bulky catalogues a simple sheet of paper is enough.
You can freely download this material at http://bit.ly/puncheck. The PDF should be printed in 100% scale and possibly laminated for greater strength and durability.
