How do I cut this compound angle?

[Jimmy Williams]

I posted a grain question several weeks back concerning this same project http://www.sawmillcreek.org/showthread.php?p=1026631#poststop
and received some great advice so I thought I would give you guys another opportunity to help out. FWIW - I decided to go with the diagonal grain direction on the pieces.

Now I am working on the base of the saber display. The top piece is 6" wide and 42" long. Each side of the top has a 20* bevel cut that goes from the outside of the stand towards the inside (if that makes sense). Check out the first picture if not. The side pieces also have a 20* cut in them as well so that they sit at a 40* angle from the top (also in the first picture).

I am now trying to cut the end pieces (second picture marked with the arrow). I have cut the same 20* angle along the top edge but, for the life of me, can't figure out how to cut the compound angles where the end pieces meet up with the side pieces. I've tried all of the compound angle calculator's out there and each one gives me a different angle to try. I'm now starting to run out of material to try the different angle setups on.

Surely there is an easier way to figure what this angle setup is? What am I missing?

[Lee Schierer]

I'm not sure I fully understand the problem, but here are the angles for each area of your model.

[Chris Padilla]

It sounds like you are trying to cut a trapezoidal shaped end piece that splays and connects up nicely with the other miters. Is that about right?

What you are making is essentially a pyramid with the peak cut off...and that is "hollow" inside. Do I have it right?

[Chris Padilla]

Okay, I did some stuff in SU for you (since you obviously know how to use it).

Am I close to what you're looking for?

[Jimmy Williams]

Chris, you have it right. That is exactly what I am attempting to do. Can you provide some insight as to how to achieve that angle?

Thanks guys

[Jimmy Williams]

Would setting the CMS to a 90* bevel and a 45* miter and then leaning the pieces to be cut at a 40* angle, against the CMS fence, give me the cut I am looking for?

[Jamie Buxton]

You can use Chris' SU model to measure the angles you need to apply to the wood. (Okay, maybe Chris didn't model exactly what you have, so you should check his dimensions before you use it.) Grab one of those beveled and mitered pieces. Draw layout lines on it so that you're measuring exactly the angles your saw needs, and use the Protractor tool to measure the angles.

[Chris Padilla]

Here, let me post this SU file and I'll measure it later and get back to you if someone doesn't do it before me.

[Jimmy Williams]

Thanks Chris. This helps a ton!!!

[Chris Padilla]

Well, it was a bit challenging but I think I finally figured out a method in SU to measure some of these angles.

I've been playing around with geometery but the equations are escaping me at the moment.

I think everything here is labeled clearly and I used your 20 degree bevel. I used a 4" "end" but it can be any size and the angles will remain the same.

Basically, what I did was create your end piece but then turned it back into an ordinary 3/4" thick board and then did some other things to get accurate measurements of the angles. These should be very, very close.