So for starters -- don't try to cut the molding flat -- I tried that,
but it takes more time, is less accurate, etc. My experience was with
5" molding, so even a fraction of a degree was very visible, and after
many attempts cutting it flat, I decided it wasn't the way to go.

I found it better to brace the piece in the miter saw at the correct
angle, cut it, try it, and if it didn't fit perfectly adjust the miter
ever so slightly, until it was perfect (for longer pieces which were
length dependent, I did my tests on a scrap piece until it fit
perfectly, and used that setting to cut the long piece).

What I ended up doing was creating a few braces to hold my pieces at
the correct angle. Each brace was simply a piece of wood cut at 45
degrees, such that the long end was exactly the length of the back of
the molding. I rested the molding against several braces for each
cut. This way the molding was always cut at the perfect angle -- no
room for slop.

Now, about your paint drip problem: First off, I would look into
getting better primed moldings without paint drops. If you can't do
that, get unprimed moldings, and prime afterwords. If you can't do
any of those two, another suggestion would be to take the braces I
described, and glue 1/4"x3/4" flat pieces of wood to the bottoms and
sides, that protrude out a little. This way the molding rests only on
two to four points, which you adjust such that they are not over any
paint drops. Excuse the ascii art, but the side profile of the brace
would look like this:

|
|
|\
| \
| \
L___\___

and it would be 3/4" thick. The braces will likely be more accurate
than the miter stops you are looking at.


Also, in the category of "learn from my mistakes", I spent a few
minutes embedding a few rare earth magnets onto my braces, as I
thought it would help hold them in place. As it turned out, my
mitersaw base was aluminum, so they had no effect. It turns out they
worked fine without the magnets.



John

(Here's a picture of my crown molding: www.ulvr.com/john/train)









John