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Hello Bruce.

My Bygrave slide rule is just a cardboard cut-out, nothing fancy needed in
terms of machining. You can see a picture of it at
www.pisces-press.com/graphics/Bygrave.jpg

The hard part is the scales, but sometime list member Zvi Doron developed a
computer program to print out scales that could be stretched to whatever
width your particular tube required. Really neat. I used the program to
generate the scales for my slide rule and Gary Lapook also used it to
generate the scales for his version. Gary brought his along to the
Navigation Weekend at Mystic, and I hope he will give us a post with some
pictures, telling us about it and some of the neat ideas he incorporated
into his sliderule.

Accuracy that both Gary and I are getting with our slide rules is about two
minutes of arc. Zvi tells me he gets one minute of arc accuracy with his,
but I know he uses a tube diameter about twice that which Gary and I used
(about 1.5 inches) and so that would account for his greater accuracy. It
takes about two minutes to reduce a sight with the Bygrave slide rule -
once you get the hang of it, of course.

Geoffrey Kolbe

At 07:39 15/06/2008, you wrote:
>
>
>I was reading in the archives about the Bygrave slide rule, and one of
>the posts mentioned that there was a link to printouts of the scales,
>but I never found the link. If some one has it, could they send it to
>me. As well, Geoffrey said he built one, and I would love to see
>pictures of his project.  I might mock one up in cardboard if I can get
>the scales.If I ever get around to mastering Solidworks, I could get one
>made on a rapid prototyping machine. Perhaps Geoffrey has the g-code?
>
>I also remembering someone was looking for seals in an odd size to
>repair an aviation sextant. Check out Rocketseals.com. I buy from them
>and they have a huge selection.
>
>Some one was looking for circular slide rules and I found a page with a
>huge selection.http://www.sphere.bc.ca/test/circular.html
>
>
>
>Thank you
>
>

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