How to do Curved Moldings

I mentioned in a previous post that there were some curved corners that had to be dealt with.  There are a couple of curved corners in the attic.  They echo a curved corner that's in the kitchen near the door that goes into the dining room.  We also used the curved corners to soften some sharp angles, in particular making the hallway feel more open than it really is.

They are cool, but you can't really run molding around them in the usual way...

The first step was to cut 3/4-inch wide pieces of base board.  Of course, you're going around a curve, so they are not cut at 90-degrees; the back side is narrower than the front.  Once they were all cut to the proper angle, I attached them to the wall using construction adhesive and to their neighbor using gorilla glue - there's just metal mesh lath and plaster behind the curve; no framing to nail into.  Then sand to round-off the joints, fill the gaps, and sand again.

The next step was to install the cap.  Same drill; cutting small pieces at an angle to make the curve.  This was the first one I did, so things didn't quite fit as well as the ones I did later.  It just required more filling and sanding than the others.  ;-)

Note that these curved walls were shaped by hand - they are not entirely constant radius.  That means the angles are slightly different for each piece of molding I cut.  The numbers on each piece indicate how many degrees off perpendicular I cut at each end (i.e., the one marked "3" was cut 3 degrees off perpendicular at each side).

After scraping off the excess glue, sanding, filling, and re-sanding you get something that looks like this photo.  Now it's ready to be vacuumed, tack ragged, and primed.

Special note: The photos are of the three "outside" curves.  There's an "inside" curve as well that I'm still working on.

It's similar, but harder.