A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: David Pike
Date: 2021 May 3, 13:44 -0700
Now look what you’ve done Tony. You’ve got me at it too when I could have been outside enjoying low cloud, torrential rain, and 40MPH winds.
I also managed to scrounge a couple of 100mm diameter balls after Christmas, so the race is on. I thought they were glass, so I had to work very carefully around the top of the first one and used my mini blowtorch to remove the trimmings. When I went to file a groove to snap the top off, I realised they were plastic, so I sawed the tops off instead. There was some trimming remaining inside the hole, so I left it there to make a base for the filler.
After that I marked out the cradle. I got the exact diameter of the globe by putting it lightly in a vice and using inside Vernier callipers to measure the gap between the jaws of the vice. I’ve not put numbers on the divisions, because I’m not sure if I want to use longitude, SHA, or RA yet, or if I need any numbers on the cradle at all. I did mark a 23.5-degree line in case it’s need later. I’ve got to wait for the plastic filler to set hard (it’s the end of a pack and getting a bit old), sand the top, and paint the globe matt-white, so I thought I might as well invest in a circle cutter to do a proper job of the cradle. https://www.ebay.co.uk/itm/233467665297?hash=item365bc1db91:g:HUEAAOSwDSxeIYTx It should be here by Friday. That’ll give you chance to catch up. I’ll test the hole diameter by cutting a circle in a bit of spare card first and checking the globe against it. DaveP