Francis Upchurch posted this last December:
"Hi,
I'm very interested in traditional celestrial nav.Not a member of Navlist yet but will join.
I would like to build a working model of the Bygrave slide rule.Could anyone send me details of the their designs/scale printing software etc?
Many thanks
Francis Upchurch
UK "
I just received this email from him off list:
"Hi Gary,
I've used your latest,
"improved "scales to build a "retro- look " Bygrave. I adjusted the scales dimensions in Photoshop 7 and added a bit of yellow"ageing " colour and a few extra numbers, and the plastic handles are from a "Kenco" coffee jar top to give it a kind of 1920s "Art Deco" feel. The cursor was made by copying from an original and laminating in plastic, strengthened with hard plastic ring ribs.Felt strips were attached with double sided "Scotch " sticky tape to add the required level of resistance.
To my sheer amazement, it is as accurate as the original, 80 year old model that I was lucky to find on ebay and which works perfectly. (see photos)
I am now using it on my yacht ( the original stays dry and safe at home) and getting to within 1-2 minutes of arc accuracy compared to a calculator.
Thank you so much for all your help with the scales, which is the only difficult part of the build.
I will write up the detailed instructions of the build
asap when I return from a months sail in the Atlantic, testing the system.
Thanks again and best wishes to all who have helped with this exciting project.
Francis"
I am including one of the photos he sent me and I can't wait to hear his detailed description of how he made it.
gl
Linked File:
https://www.NavList.net/imgx/DSC_0063.JPG
