Fellow Shadow Watchers,
Professor Noel Dilly and Sarah Edmondson-Jones
recently exchanged ideas about materials for sundial making which called
to mind being asked to make a 'budget' sundial for which the first
suggesion was marine plywood. The architect involved claimed problems
with delamination and suggested 'Exterior Grade MDF' instead (Medium
Density Fibreboard for non-UK readers) and, although I'd never used it, I
expressed grave doubts as to its durability. To put the matter to a
crude test I immersed narrow strips in water for two weeks while checking
for water penetration and signs of delaminating, swelling, softening etc.
While not totally impervious the results were most impressive.
In many respects it's the perfect material being flat, smooth, fairly
cheap and unlikely to warp or twist in addition to being iso...???
(forgotten the word) meaning 'working equally easily in all directions'
In some ways it is like non-brittle slate. Given edge-sealing and a coat
of paint I think Exterior Grade MDF is a good candidate for large,
low-cost dials. A woodworking router with a 'veining' cutter for
hourlines and some templets for numerals should yield a good-looking
'carved' dial which would be cheaply replaced as the years take their
toll.
To meet budget and deadline I stuck CNC-cut PVC numerals on with
cyanoacrylate gel to combat the expansion/contraction of the two
materials at different temperatures.
That is one sundial which will never appear in the BSS Register I think
Patrick. ;-)
Tony Moss
P.S. to my JPEG sub-listers - patterns are still at the foundry awaiting
casting.
