On Sun, 19 Jun 2005 16:00:39 GMT, wrote:

Hello,

I have a cope joint to make in some 2.5 inch mape crown moulding.
I just need a quick sanity to check to make sure I'm doing this right
because my first couple of test pieces just weren't making it.

First I put an inside miter on the crown. I do this by laying the crown
upside down against the table and fence of my miter saw and mitering it at
45 deg. This worked fine for the outside corners so I'm assuming it should
work to get an accurately cut inside miter. If it doesn't then I must be
really missing something....

This is correct as long as you are holding the crown at the same angle
as it fits on the wall. I assume that you did this on the outside
cuts so I think you have that correct.
You might check it by taking one of the pieces with an outside cut
(that you know is good) and hold that on your fence as if you were
going to cut it again. Without cutting, mark a pencil line on your
fence along the top (which is really the bottom) of the crown. When
you get ready to cut your inside 45s bring the crown up to your
reference mark.

Then, as one previous poster suggested, I back cut it wayyyyy past where I
think it needs to be back cut to, and then back cut it a little more
following the pencil line on the face of the cut.
When I put the coped end up against a butt end at the spring angles they
don't even seem to want to meet. They are kinda sorta getting there but
they aren't close enough to where you could start cleaning them up with a
rasp.

Am I missing something fundamental here?

You are on the right track.
Make sure that the piece you are fitting to is installed at the
proper spring angle against the wall. If the cope is more open at the
top or bottom (not all the way along it's length) this is usually
evidence that the first piece is installed too high or too low. You
can cut and cope the proper angle on the new piece but if the
installed piece is too high (on the wall) or too low a good cope will
not fit.
You can measure the reference mark on your saw fence and measure down
the wall to be sure that measurement is the same.

My cut along the face was pretty accurate, not perfect, this stuff is really
hard to cut, but pretty close to the line. Maybe not back cutting enough?

You can try to check that by rubbing a pencil all over the high spots
on the back of the cope. Then, hold it up to the piece on the wall
and kinda wiggle it a little to see if you can transfer a mark to the
piece on the wall. If you see some marks on the installed piece you
will know that the back cut is not enough and also where you need to
take some out. I know this isn't too scientific but assuming that all
of the other things mentioned above are correct, this is worth a try.
I've been coping crown for a long time and once in a while I still
won't get enough undercut.

Good luck and let us know how it's going.

Mike O.