Vertical declining sundial

[JOC]

We have a sundial (not a home-made one), I got my parents a fairly expensive professionally made one for their ruby wedding anniversary, it came with finely etched markings and an equation of time all set-up for this location.  It was a tricky object to get fixed and aligned at precisely the right moment in time and I had to buy it a pillar.  It was also difficult to find a place in the garden to site it for 'maximum time in the sun' duration, however, taking the equation of time into account I am amazed at the accuracy of it whenever I compare it to my watch.  Its a lovely idea to make your own.

[iapa]

On 04/04/2017 at 16:20, furrysocks2 said:

Something for the garden, the intention being to fabricate something in metal - this thread for recording progress.

 

Starting with a prototype...

Source: http://www.pandy.me.uk/sundials/wd_calc.htm

 

When the sun was directly opposite the dial, it was approximately 12:53 GMT. My longitude is approximately 13' W and the equation of time is approximately 3' (sundial slow). Not quite getting my head around why, but 0h53' - 13' + (-3') = 0h37' (or 9.25 degrees).

Stellarium gives the declination of the sun today as approx 5.88 degrees, and my latitude is approximately 56.25 degrees.

Following example 3 from the link above and plugging into the calculator, I get approximately 12 degrees azimuth from south (confirmed in Stellarium), giving gnomon side angles on the west and east faces as 102 and 88 degrees, respectively. Running these two figures through the calculator, I get the following results:

 

Ignoring the lengths and drawing the angles FCG out on a board, I get:

 

I cut off the bottom corner and made a 32.9 degree ACD gnomus, the yellow one to stick out from the face at 90 degrees, but rotated by 9.25 degrees to point south, I think... and hot glued it on.

 

Looking again at the calculator results, it should have perhaps been rotated by 7.9 degrees, not 9.25, the 1pm line being at 8.4 degrees.

Unfortunately, the sun's gone in and I don't know if I'll get to test it today. Next weekend, April 15th, the equation of time is 0, so if I've built it correctly, it should read correctly.

Will watch with interest as I was considering a sundial that I can put on top of a pier for this times when I holiday (I'd take the mount off).