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Thursday: A bright morning with only a little wind. Time to hang some shutter ribs off the dome. Until I have tried them in place I have no real idea about rib depth [projection] or clearances.
In fact it proved far better than expected. With two half ribs clamped to the obs. slit rib I was able to touch all the points of the tiers with the inner edge of the shutter rib. This provided an 11cm projection beyond [above] the slit rib.
By cutting away the small isosceles triangles, where the inner edge of the rib met the dome, on the corners, the projection would reduce by about 2cm. 9cm is less than 4". I can't mark these cut-outs until the complete ribs are prepared.
This would nicely close the gaps between the rib along the facets of the dome without leading to an "untidy" looking edge on the inner arc of each outer rib. Bringing them closer in, with more overlap, should aid weather proofing of the shutters to wind driven rain or snow.
This would nicely close the gaps between the rib along the facets of the dome without leading to an "untidy" looking edge on the inner arc of each outer rib. Bringing them closer in, with more overlap, should aid weather proofing of the shutters to wind driven rain or snow.
The single shutter rib shown will eventually become the outer, visible edge of the shutter door on that side. There will be another rib on the far edge, outside of the other slit rib. As seen in this second image. Where two outer ribs are temporarily clamped to the slit ribs. The F-clamps jaws aren't really long enough to get a proper grip.
Two more ribs will meet, face to face in the center of the observation slit. The spaces between the pairs of ribs will be joined by battens to stiffen the shutter skeletons. Finally followed by 4mm birch ply covering of the surface.
First I must join each pair of half arcs, end to end, to make complete ribs. The end cuts will be skewed, patched with more 12mm ply on the inside face and then the arcs will be screwed and glued together.
The image shows progress as the second shutter rib is patched, glued, clamped and screwed. Spare ribs are being placed underneath as a guide to ensure the two halves are a true curve and not "bent" in the middle. A polythene bag is used as a glue barrier. Just to ensure the guide ribs don't end up adhering to the two halves being glued together. The plywood, reinforcing patches will be arranged inside the shutter doors to become invisible.
I need the finished shutter ribs for checking the smoothness of the curves of the next two. But still put off un-clamping them until tomorrow. Once I have the two earlier ribs unclamped I can try them on the dome for marking the facet corners for trimming the shallow notches. A couple of crossbars for spacing would help compared with trying to clamp individual ribs. I can hook the top crossbar over the observation slit's top bar for security. Lifting two ribs up the outside ladder should be fun!
It has now reached 62F as I pause for lunch. I really ought to return to the sealing of the trapezium panels this afternoon while the weather is fine. And did. Spent another hour sealing the gaps between panels. The brown turned out to be metallic bronze and just as disfiguring on bare birch ply. It is lucky I intend to paint.
I now need a wider blade for the multi-cutter to open up the gaps between some panels. They are too narrow to take the sealer which merely smears over the top and offers no guidance to the nozzle tip. The dried sealer feels firm enough to be sanded after a few days. Though I haven't tried it yet. There might still be a chance to improve the "cosmetics" of my clumsy "caulking." An oscillating, knife/scraper blade might work too. I still haven't found a depth gauge at a sensible price in Denmark. So will have to make my own.
The image shows progress as the second shutter rib is patched, glued, clamped and screwed. Spare ribs are being placed underneath as a guide to ensure the two halves are a true curve and not "bent" in the middle. A polythene bag is used as a glue barrier. Just to ensure the guide ribs don't end up adhering to the two halves being glued together. The plywood, reinforcing patches will be arranged inside the shutter doors to become invisible.I need the finished shutter ribs for checking the smoothness of the curves of the next two. But still put off un-clamping them until tomorrow. Once I have the two earlier ribs unclamped I can try them on the dome for marking the facet corners for trimming the shallow notches. A couple of crossbars for spacing would help compared with trying to clamp individual ribs. I can hook the top crossbar over the observation slit's top bar for security. Lifting two ribs up the outside ladder should be fun!
It has now reached 62F as I pause for lunch. I really ought to return to the sealing of the trapezium panels this afternoon while the weather is fine. And did. Spent another hour sealing the gaps between panels. The brown turned out to be metallic bronze and just as disfiguring on bare birch ply. It is lucky I intend to paint.
I now need a wider blade for the multi-cutter to open up the gaps between some panels. They are too narrow to take the sealer which merely smears over the top and offers no guidance to the nozzle tip. The dried sealer feels firm enough to be sanded after a few days. Though I haven't tried it yet. There might still be a chance to improve the "cosmetics" of my clumsy "caulking." An oscillating, knife/scraper blade might work too. I still haven't found a depth gauge at a sensible price in Denmark. So will have to make my own.
Click on any image for an enlargement.
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