the cut n crown is sort of a solution. The issue that I have with this is that they have you cut some of the crown face in. That screws with the angles. 48 deg from the face is not the same as 48 degrees from the back. Its all the chop saw's fault!
take your average 2x4, from the back to the end it's 90 degrees. From the end to the face it's 90 degrees. No matter what angle you cut, remember that they both equal 180 degrees.
cut a 2x4 on 45 degrees. measure the cut: from the back it will be 45 degrees. From the front it will be 135 degrees. add both up and you get 180!
So if you cut your 2x4 at 38 degrees, the complimentary angle (the one that you will use) is 142 degrees.
Why is it the saw's fault? because the scale is set to measure from the BACK! aha! so how do we compensate for that?
We use the complimentary angle! allow me to 'splain:
get yourself an angle measuring tool. You can find some digital ones now for about 20 bucks. turn it on, wrap it around an outside corner (or inside, makes no difference) note the measurement.
Lets say that your device reads 88 degrees. Aha you say! 1/2 of 88 is 44! well yes it is, but the scale on our saw (all saws) measures from the back and not the front. We want the front!
So knowing this we want the complimentary angle. 180 minus 88 is 92. 1/2 of 92 = 46 degrees. That is now our chop saw setting. Set your chop saw to that angle (46) and you will be dead on.
As others here have said, cut your crown "nested" ie rest the crown up against your chop saw fence and adjust it to the angle that it will sit on the wall. Mostly it will be 45 degrees, but sometimes it's a 38/52 degree situation.
use crown stops on your saw, you don't have to spend bucks on this, a piece of 1x4 and two clamps -done.
I've used this method for several years, and it works.
Oh and what others here have said, cut it upside down on your saw, NEVER backward (face in) always face out! if you cut it face in? your angle is now 88 deg (44) not 92 (46) Thats the flaw with the cut n crown system.
I now have a kapex saw, with the included angle finder. It's really nice, but I find that I can only do one corner at a time. I like to measure the whole room on a drawing, mark down all of my angles and then take that to my saw - but this is such a sweet saw that I will learn to be quicker
I don't suggest a kapex, as it's about 1,300 bucks. Lot's of money for a saw that you'd use now and then. But wow is it ever sweet to use