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    Re: Manufacture new Bygraves?
    From: Gary LaPook
    Date: 2009 Jul 03, 13:02 -0700

    I have had great success with printing the scales of the flat Bygrave
    and wrapping them around a tube and sealing them in place with clear
    adhesive plastic sheets.
    Here are some pictures of one example:
    Links to the scales:
    I picture of one made by Geoffrey Kolb:
    Try it.
    Hanno Ix wrote:
    > Hello:
    > I agree. Bygraves could be build.
    > However, there are some cumbersome questions, the most obvious being,
    > How to generate a drum-shaped scales with the required accuracy and
    > resolution. Remember, we will have to maintain sub-millimeter acc/res
    > over many turns, with "many" meaning perhaps 20 to 50. This should be
    > possible, but is still not easy.
    > If someone could generate the mechanical construction and quality
    > assurance methods for this challenge we could talk about manufacturing
    > more seriously. Her are my ideas:
    > Personally, I am thinking of an ink-jet head printing on a turning
    > drum where the printing is synchronised with a digital encoder on the
    > drum' s axis. The process control could be handled by one of the
    > relatively simple contollers on the market.
    > Another approach would be to replace the ink-jet printing with an
    > engraving system.
    > With the first  I personally have experience, with the second none
    > whatsoever.
    > However, more problems lurk. What are the limits for excentricity of
    > the drums when in use? How about friction? How to stabilize the thing
    > when under the influence of temparature changes, humidity, sun's UV,
    > spray salt water, etc, etc.
    > So, you can see that the conceptual simplicity of the Byraves is
    > offset by many practical obstacles.
    > Compare this, for instance, with the Ageton method (H.O. 211)! Only 12
    > pages of a table, a sheet of paper and a pencil is virtually all you
    > need to get a generally higher res/acc than with a practical Bygrave.
    > Yes, you will also need the skill and concentration to exercise the HO
    > 211 calculations under virtually any condition at sea - particularly
    > when you are a submarine commander at war. Well, I guess, in this case
    > a Bygrave, well designed under a government contract, does make sense!
    > --- On *Fri, 7/3/09, Greg Rudzinski //* wrote:
    >     From: Greg Rudzinski 
    >     Subject: [NavList 8924] Re: Manufacture new Bygraves?
    >     To: "NavList" 
    >     Date: Friday, July 3, 2009, 9:40 AM
    >     There must be a combination of PVC tubing that fits on itself snugly.
    >     If the white PVC were engraved with black and red scale markings as a
    >     regular plastic slide rule is then I think you would have something.
    >     On Jul 3, 12:18 am,      > wrote:
    >     > A few years ago, when I and a couple of friends wanted each to
    >     own a gear hobbing machine, we cooperated. One made the casting
    >     patterns and saw them through the local foundry, another did the
    >     heavy machining and I did the small parts like feedscrews and
    >     their nuts. It occurs to me that several handy people could
    >     combine their skills to produce replica Bygraves slide rules.
    >     There will surely be someone who knows where to access tubing in
    >     which each size nests snuggly in the next largest size, someone
    >     else will know how to produce hard-wearing replica scales, another
    >     may be prepared to turn the bobbins at each end and I would
    >     volunteer to do small bits of metalwork. The results do not have
    >     to make profits, though a little would be nice. Since there seem
    >     to be very few surviving Bygraves calculators, one could at least
    >     have the satisfaction of owning a replica. The starting point of
    >     course would have to be accurate, dimensioned drawings of an
    >     original, preferably following the metric system, so the
    >     manufacturing consortium would not have to be confined to the USA.
    >     >
    >     > Any offers/takers?
    > >
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