I've been somewhat distracted by my conversion to grand-father-hood this weekend, so haven't achieved an awful lot. Nonetheless, there is some progress to report. Firstly, the inner shelf:
Half-lapped masons mitres seemed to me to be the only way to make any sort of proper joint between the members, given that they all had to slot into grooves. Obviously full mitres simply couldn't work geometrically. Whilst the glue was drying on that, I drilled drainage/ air-circulation holes which would take any leaks that got in around the glazing back out to the outside:
I then did a beautiful job of chopping in the rather tasty SS cranked 3" ball-bearing hinges I'd bought for the job:
.....only to discover that it is impossible to hinge the casement on the side, as it fouls the projecting cill. Not just slightly, either. I would have needed to cut about an inch of material away to form a clearance. I'm such an idiot sometimes.
The only place such hinges could possible work was on the top end, where the upstand was at its highest:
This left me with some repair work to do:
Next came something of a quirky thing. Under the internal projecting shelf was to be fitted a decorative skirt, to seal off the junction with the plaster. However, I have an additional task in mind for it, which is to hold a secondary glazing panel in winter. Because I wanted to make that secondary panel, I needed to know the size of the opening inside that skirt, so I decided to make it and attach it prior to fitting. Firstly, this was risky, because the fit had to be tight enough not to be horrible decoratively, but loose enough that I could just drop the entire rooflight into place as one complete unit without fouling on the existing plaster.
I took some pinch sticks in and very carefully gathered my measurements. Obviously, this skirt would need to be properly fixed at the corners, so some quick 'n dirty dovetails (they'd never be seen). No real marking out for the tails:
I took the dry-fitted skirt up to the opening and tried it, noting the diagonals so that I could replicate those at glue-up.
Those who think of dovetails as high end stuff should take a look at those photos. Probably quarter of an hour of work and I'd got 4 rock solid corners. Low skill/ high strength and accurate. I think the only competitor would have been some 2" nails, but into 15mm timber that's something of a gamble.
I glued the apron in place:
On to the removable secondary glazing. I ripped and planed some more Douglas Fir. From memory the section was about 45x30mm. After cutting to length and running a big rebate around the pieces, I then cut back the ends in preparation for my corner joinery:
I was pretty pleased with them:
Everything on exposed painted joinery gets rounded over. This is to ensure that the paint remains thick enough at the arris, otherwise this is a weak spot where failure will eventually start:
I'd contemplated many different ways of holding the secondary glazing in place, and in the end settled for making my own mechanism. I started with a scrap of aluminium (I'd guess at about 2mm thick, maybe 2.5):
The nice thing with working aluminium as compared to steel is that ordinary woodworking tools can be used. I swapped to an old blade on the bandsaw, and an old belt on the belt sander, and started work:
Everybody has a spring collection, don't they:
It's hard to find 4 the same in mine, so I was a bit limited. I came up with these:
With a scrap of straightened fencing wire I mocked this up on an off-cut:
Then chopped away the relevant parts of the sides of the frame, before fitting the mechanism:
That's repeated on the other side, and now I'll be able to just push the window up into place and it will click into position over 4 screws. Pushing the lever will release a side at a time when I want to remove it.
All I had time left for was a splash of thinned Bedec MSP as a primer/ undercoat: