Thanks for posting a methodology for calculating the saw angle for blanking dies.
I would then draw a line across the portion
representing the blade thickness from the upper right hand point across
to the lower left hand point or vice versa. This would give me the
proper angle to use to saw a blanking die. This way you can figure for
metal and blade thicknesses not on charts.
Let me rephrase it in my words to see if I understood it correctly.
Consider the thickness of the metal to be cut as the length of one side (
a) of a right triangle. Use the blade thickness as the length of the other
side (b) of the triangle. Now use your high school trigonometry ( you do
remember it don’t you?) to calculate the angle. It real easy with a calculator
that has trig functions.
0.125 (1/8") steel thickness
0.020 # 7 saw blade thickness (see “The Complete Metalsmith” page 183)
Draw a right triangle with a height of 0.125 inches (side a) and a base
0.020 inches long (side b).
Now calculate the angle A (that’s the one at the intersection of side b &
the hypotenuse (side c).
- Tan A equals a/b
- Tan A equals .125/.020
- Tan A equals 6.25
A equals 80.9 degrees (rounded to the nearest tenth)
Step 3 can be done with a calculator or looked up in a table of Natural
Trigonometric Functions. The calulator is the quickest.
Let us know if this is incorrect.