I've been known to take a piece of offcut plywood ....maybe 12" square...and cut a 45deg. angle on it. Lay the long edge of your trim against the 45, and cut the angle from that...60deg... depending where you're measuring from.
Perhaps safer if you run a 2' piece of 1x4 across the rear fences (There should be a couple of small screw holes in the rear fence which would allow you to 'clamp' the 1x4 rigidly in place).
Work back from that.

 

Perhaps safer if you run a 2' piece of 1x4 across the rear fences

Why is this safer?

 

Mike if you were concerned you could always clamp a piece of mdf etc to the saws table to act as a side support to better keep it in place as your cutting

 

Mike
here is oneway

 

That's exactly what I was reffering to

 

I think this is what Dan is suggesting. It's the method I have used several times. The 45º angle acts like an auxiliary fence that you can hold the board against it safely while keeping your hand away from the blade. Set your saw for a 30º cut to get the 15º angle you need. I actually made my 45º triangle with a 2" high fence on the hypotenuse because I use it often when I need odd angled cuts.

 

Yes Oliver that works, the reason I do the other way I get to move the saw blade away from me just feels safer to me.

 

use a jigsaw..
hand plane the cut w/ a LA block plane and shooting board if you need meticulous clean cut/miter...

 

I don't have a block plane or shooting board yet. In fact, my son and I are going to a gathering of woodworkers in January to learn this technique. When I say beginner, I'm serious. The few projects I've made so far are not even good for firewood (made from pine), but I'm optimistic that things will finally start to improve.

Thanks for these suggestions. It all makes sense once you see it.

 

The shooting board...

hand item...

.

 

+1 with Semipro, Gaffboat and Stick...

The additional piece to act as a secondary fence perpendicular to your work piece is real easy...clamp it to the left side of the SCMS as drawn and make sure your work piece is well secured so it doesn't tip and so you don't have to keep your hand close to the blade to hold it...

When using the jig saw Stick suggested, clamp an edge guide to your work piece so you cut nice and straight...then sand as desired...

Good luck...be safe...