|
One of the disadvantages of a tall observatory (5.2 metres in my case) is that you can't readily get to, or even see, all the parts. Recently, when I did get to see the sliding shutter frame, I was horrified to find that part of it was almost completely rotten and would need replacing.
I bit the bullet and decided to make an aluminium frame rather than copy the original wooden design. The two side rails were cut from a 6.5 metre length of 50 x 50 x 3 mm square hollow section rolled to (hopefully) the correct radius.
I can never cut square with a hacksaw, so used an old mitre saw that still had its original blade (from 1986). It did a great job!
The design is simple: three lengths of 10 mm threaded rod, with a couple of 35 x 10 mm sealed bearings on each, to space the rails the right distance apart. The skin is 0.55 mm 'sign white' sheet metal, which I will pop rivet to the Al frame.
I need to hire a cherry picker to remove the old shutter and install the new one. I'll combine this with a total re-paint of the dome - the last time was in 2014.
|