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Suppose you’re working with crown moulding that does not make the typical 52/38 degree angles with the wall and ceiling. I’ve found a way to “trick” my Construction Master IV into giving me the correct mitre and bevel angles. The only information you need is the crown moulding angle, which is very easy to find. Just cut a small piece and trace it onto the corner of a piece of plywood or whatever, and measure the angle with your angle square or with a compass.

b This method is for rooms that have square (90 degree) corners only.

In the example below, the calculator is used to find the mitre and bevel angles for 52 degree crown moulding. When you hit the pitch button in the last step, you should get 31.62 for the mitre and 33.86 for the bevel. For any other crown angle, simply replace the 52 with the new angle and follow the same steps.

b The Mitre Angle

1) conv x

2) 52 pitch

3) 1 = diag

4) run = rise

5) 1 = run

6) pitch

b The Bevel

1) conv x

2) 52 pitch

4) run

5) conv (squareroot symbol)

6) + 1 = (squareroot symbol)

7) conv (divided by symbol)

8) x rise = rise

9) 1 = run

10) pitch

It is possible to get the calculator to do this for ANY wall angle in combination with ANY crown mould angle but there would be quite a few more steps involved. I may post these later if there is any interest at this site.
I don’t believe that earlier models of the calculator will yield the correct results.