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    Re: Bygrave slide rule , o-rings, circular slide rules
    From: Gary LaPook
    Date: 2008 Jun 15, 08:29 -0400
    Gary LaPook writes:

    I am in Montreal now but I should be back in California in about three weeks and I will then be able to put up information on my Bygrave reproduction.

    gl

    Geoffrey Kolbe wrote:
    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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