I recently did just this for a stand alone cabinet and srv52761 is right on the money with
Set your blade bevel to 30°
Set your miter gauge to 35.3°
for a 45 degree beveled miter.
I understand that logic would say that one of the angles should be 45 degrees but that's not how it works out. You may have to fine tune your settings depending on your saw but start here and you'll be very close if not right on.
Cliff
I placed the molding against my fence and the blade clears by about 1/4", so I should be good. Once I cut it that way, I'll play with the saw and the (now-cut) trim to figure out miter/bevel angle needed to cut it laying flat and see if that's easier or safer.
Thanks a bunch, guys. I just needed a sounding board to bounce ideas off of and get past that block!
srv52761 is correct. You need to know what the spring angle of your crown molding. Just from looking at your picture I would guess it is 52-38 so to me if your crown is 52-38 set your blade a 33.8 and your miter gauge to 31.6. Kreg also sells a crown molding fixture for some where's around $40. You will have to put on an axillary fence for the height and set you miter gauge at 45 degrees. It is for doing crown molding on a miter saw but it will work, just follow the instructions. There are other manufactures that also make something similar.
Tom
I went to the lumber store and bought a inside and outside angle piece to help get me started
Whelp, the 10" blades on my RAS and table saw aren't tall enough to do the job so I ordered a 12" Bosch SCMS. I'll likely sell the RAS as my space is limited and the SCMS will do everything I use the RAS for.