Hi John,
I can offer:
J. Davis: ‘Alightweight laser trigon for layout of sundial lines’, BSS
Bulletin, 11(iii), pp.144-146, (1999)
which included drawing analemmic hour lines, and for an earlier purely
mechanical example (built of Meccano!) there was
Noel Ta'Bois: 'Sundial Line Drawing Jig', BSS Bulletin 92.3 pp 28-30 (1992).
Regards,
John D----------------------------Dr J Davis
Flowton Dials http://www.flowton-dials.co.uk/
BSS Editor http://sundialsoc.org.uk/publications/the-bss-bulletin/
From: John Pickard <[email protected]>
To: Sundial List <[email protected]>
Sent: Wednesday, 7 September 2016, 1:14
Subject: Using linkages to draw curves on sundials
Good morning,
While researching mechanisms of wire strainers used to tighten wires in
fences, and trying to find the theoretical mechanical advantages of the
different mechanisms, the first thing I learned was that "linkages" are the
key to many of them. There's a whole branch of mechanics devoted to the
theory of these things which involve a zillion combinations of pivots and
links to achieve various purposes, usually to transmit motion in a specific
manner.
The best explanation I found was Slocum, A. (2008). Fundamentals of design.
Topic 4. Linkages
(http://web.mit.edu/2.75/fundamentals/FUNdaMENTALs%20Book%20pdf/FUNdaMENTALs%20Topic%204.PDF).
3.3 MB
But my curiosity lead me further, to a more mathematical treatment.
Unfortunately and for unknown reasons, the Jefferson Lab Library has removed
the title page.
Bizarre! I contacted the library and they gave me the full title etc.
Svoboda, A. (1948). Computing mechanisms and linkages. MIT Radiation
Laboratory Series, Volume 27. New York, McGraw-Hill.
(https://www.jlab.org/ir/MITSeries/V27.PDF) (CAREFUL: 40.8 MB)
Among other things, this book shows how you can use mechanical linkages of
various forms to draw the curves of mathematical functions. And seeing that
the curves on sundials are all defined by equations, I was wondering if
anyone knows of any attempts to make a mechanical device of links and pivots
specifically for generating sundial equations, and thus drawing sundials? It
seems to be a feasible but complicated way of doing it, with some serious
mathematics behind the linkages.
I don't include sundial rulers in this, as they are not physically linked
and pivotted. Similarly, I don't include CNC machining as this involves
moving the tool / work using a pre-programmed series of x, y and z
coordinates. And of course, 3-D printing is out.
(And I still haven't figured out what sort of linkages are used in the wire
strainers I'm studying!)
Cheers, John
John Pickard
[email protected]
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