In case anyone is interested, I thought I'd update this thread to show the results.
To recap, we have two pine beams, 40 cm square and 7.1 m long. We want a half round moulding on the bottom edges of the beam, where the moulding is about 2.5" diameter.
First job was to plane the beam to remove sawmill marks, first with a Dewalt planer, then the trusty No 4.
Next cut off the two arrisses on the bottom side of the beam with the track saw. Obviously I couldn't balance the track on the edge of the beam so the saw was screwed to a 3" x 6" block to act as a fence. A track saw set to cut a 45 degree angle screwed to a big chunk of wood is an unholy mess that won't balance anywhere and it fell on the floor a couple of times.
Next, move the fence to cut the far side of the quirk. Nice and easy this one, apart from the bit that ended up being cut at the wrong angle due to dropping the silly saw and not checking if it had moved the angle setting.
Final saw action was to cut the other side of the quirk using the track saw on its track, almost relaxing.
Ending up here:
To try and maintain my sanity, I did the same operation on each side of the beam, before moving on the the next operation. I made the the ends of the beam round with chunks of wood cut out on the bandsaw and screwed them on, so it was fairly easy to roll it from one side to another:
Now I had the moulding shaped like half an octagon, the next job was to plane the half octagon into a half sixteenagon. You can see the four little triangles that needed to be planed off on the drawing at the top of this post:
The final stage was to plane off all the sharp edges to make the moulding round, followed by hand sanding at 80 grit to blend the whole thing:
Done and oiled:
Lifted into position with Skyhooks (tm):
Although I first posted about this back in February, we've had a few other projects and distractions so this has been on the back burner for months. Once we got around to it, each beam took about two days to prepare and we probably spent around half a day each messing about with equipment and lifting into place.