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    Re: Postscript code for making Bygrave Scales
    From: Wolfgang Hasper
    Date: 2014 Mar 31, 18:03 +0200

    thanks for posting this, this is very interesting!
    And the dots at the 30' marks for the MHR scale- 
    wonderful ;o)
    I still have plenty tubes for cylindrical slide rules, 
    matching the original MHR dimensions, in fibre 
    reinforced plastic. 
    In all there are 3 tubes (cotan scale, cos, and cursor) 
    plus a slightly thicker stub to be the handle. I can 
    machine the 20 groves, these indeed give good grip.
    I use my working copy and it works a charm. No lookups 
    but the almanac data! 3D printing might be nice, but 
    is not really necessary to come very close to the 
    original. My simplified multi-cam locking mechanism 
    works even when quickly hand-cut with a jigsaw...
    The whole thing is very light weight and waterproof. I 
    also made it a protective case from 3" drainpipe.
    see my earlier posts or contact me directly if you are 
    interested in more detail.
    For me, making the scales to measure was the hard bit.
    But was kindly offered help, thanks again!
    Best regards
    Am Samstag, 29. März 2014 16:56 schrieb Robin Stuart:
    > Off and on over the past few years I have been
    > developing Postscript code to produce Bygrave line
    > of position slide rule scales. An earlier version of
    > the code was posted previously
    > http://fer3.com/arc/m2.aspx/Bygrave-Stuart-apr-2011-
    >g16126 and was used to produce Bygrave reproductions
    > http://fer3.com/arc/m2.aspx/MHR1-reproduction-Hasper
    > http://fer3.com/arc/m2.aspx/MHR1-reproduction-Morris
    >-apr-2011-g16115 In those versions the rules for the
    > scale ticks were programmed in the Postscript code
    > itself. It became clear that there is enough
    > variability and idiosyncrasies between the original
    > Bygrave, the Höhenrechenschieber MHR1 and modern
    > incarnation in the form of flat Bygraves that this
    > approach is not workable. Instead the new Postscript
    > code I have written requires that the
    > characteristics of each and every tick on the scale
    > be specified either by reading the data from an
    > external file or embedding it in the Postscript code
    > itself. The required data can be easily generated by
    > a high level computer language or perhaps a
    > spreadsheet. Embedding the scale data in the
    > Postscript creates a self-contained file that could
    > be sent directly to a Postscript printer if such
    > things still exist. For development and tweaking I
    > find it faster and more convenient to read the data
    > from an external file. This works fine on my Windows
    > XP computer but so far I haven’t been able to get it
    > to work under Windows 8.1. Something to do with
    > access permissions I guess. Any suggestions?
    > I attach a document explaining how to run the code,
    > some examples of the output that is possible and a
    > zip file containing the code needed to produce them.
    > I believe that the code could be used to produce a
    > practical modern Bygrave for actual sight
    > reductions. This would probably require plastic
    > tubes to be ground to precise diameters but to date
    > I have not located a facility to do this. I appears
    > to be relatively straightforward to produce the end
    > caps, locking knobs and other fittings by 3D
    > printing.
    > Robin Stuart
    > ----------------------------------------------------
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    > Attached File:
    > http://fer3.com/arc/imgx/BygraveScales.pdf Attached
    > File: http://fer3.com/arc/imgx/BygraveAltFlat.pdf
    > Attached File:
    > http://fer3.com/arc/imgx/BygraveFlat.pdf Attached
    > File: http://fer3.com/arc/imgx/BygraveMHR1.pdf
    > Attached File:
    > http://fer3.com/arc/imgx/BygraveMkIIA.pdf Attached
    > File:
    > http://fer3.com/arc/imgx/Stuart-BygraveFiles.zip
    > View and reply to this message:
    > http://fer3.com/arc/m2.aspx?i=127398

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