Dear John,
Many thanks for your comments...
> Have you considered using the ...
> "connect the dots" method.
Well that's what I normally do but I
set out the dots directly on the wall.
I have a collection of strips of bendy
wood which I use for joining the dots!
The problem with transferring a drawing
to a wall is that when you prepare the
drawing you probably assume that the wall
is both vertical and flat.
For dials that are around 1m square you
can probably get away with this assumption
but it is inadvisable with a dial that is
around 6m square.
Building tolerances seem surprisingly
lax to those who are used to precision
engineering.
These days, if you build a wall out of
stone blocks all kinds of checks are
made using surveying instruments but
no one seems to care if the top of a
22m building is 22mm out of true.
This is an error of 1 in 1000 which
really is of no consequence to the
builders but it IS of consequence
to a sundial...
The nodus height effectively increases
(or decreases) by 1mm every metre down
the wall you go from the horizon line.
This means the shadow of the nodus will
be lower (or higher) than you expected.
You need to stretch (or shrink) your
drawing in the vertical direction.
It gets worse because the wall will
almost certainly undulate a little too,
with bumps and dips. Stone blocks are
never laid EXACTLY square on top of
one another.
I quickly gave up the idea of transferring
a drawing for a large job.
As I said earlier:
Real life is tough :-(
Best wishes
Frank
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