Safely cutting angled sides of box

[bmuir1616]

I am building a truncated pyramid 3/4-inch plywood box for my son. It is about 23 inches square and 22 inches high. It has four panels whose top and bottom edges are cut at a 9 degree angle so the tapered box will sit flat on the floor. The four sides are straight cut at the same 9 degree angle.
The top and bottom edge cuts are easy.
What is the safest way to cut the eight sides of the box?
Thanks for the help,
Bill

[LCHIEN]

basically what you have is an inverted mitered box.
Use a compound miter calculator to cut the sides for the four sides.
like this one:
http://www.woodworkersguildofga.org/...Calculator.htm
basically, 4 sides, 81 degrees (complement of 9 degrees).
it says you need a blade tilt of 44.3 degrees and a miter bevel angle of 81.11 degrees (try the calculator, it has illustrations of the cut setups)
After you've cut the four miters, then you can cut the top and bottom edges at 9 degrees before you assemble it.

[cabinetman]

There are many compound angle calculators available to help figure the cut...Here's a few more:
http://www.pdxtex.com/canoe/compound.htm
http://jansson.us/jcompound.html
I find it easier to do the bottom and top cuts for the bevel first, if you start with blank panels, as they are a PITA to do after the sides are angled and beveled.

If the top is pointed, the bottom bevel can be cut, and the side angles and bevel are cut with the same saw setting. It might also help to draw a light line for the angle cuts as you'll see if you're off.

.