Fiberglass Equatorial Sundial

My equatorial sundial is inspired by the one created by John Wallin at: https://www.instructables.com/The-Equatorial-Sundial/ and the one in front of the Adler Planetarium in Chicago.

Except for the gnomon, which is made of copper, the entire clock is made of fiberglass and polyester resin.

I used John Wallin's plans modified and adapted to my design, also taking into account the latitude of the place where the sundial is to be installed, 40.1º.

I printed the parts in real size, glued them onto the cardboard and cut them out.

With contact adhesive, one face is glued to the inner sides and then reinforcing “ribs” are added inside; then the second face is glued (bear in mind that if a piece of cardboard has to be folded, it must be cut in the direction that makes it easier to bend).

I made the base and its front sides "in situ" because it was much easier for me than designing them:

The hole for the equatorial ring should be marked but not done until the fiberglass piece is made.

2. Equatorial ring

We make a mold in cardboard, with an extruded semicircle.

I cut out the different pieces in fiberglass (weight 450 g) and then glued them with polyester resin on the cardboard.

I repeated that last part three more times for a total of four layers of fiber and resin.

Once the equatorial half-ring had been removed from the mold, I realized that the four layers were insufficient and I decided to add other four layers to make it more consistent. As the mold was broken, I had to glue the fiber directly and that caused, when it

forged, its tightening inwards and closed the ring a few cm. I corrected this error by adding a 5 mm threaded rod, which goes through the belt diametrically so that, by means of washers and nuts, force its opening to the expected radius of 34 cm.

I attached the belt to the ring from behind using pieces of fiber. Finally and after drilling the meridian ring, I glued the 12 mm copper rod using 2-component adhesive.

I made the numbers and marks from a printed template, cutting them out on a plate with two layers of fiberglass. I also made the decorative pseudoscrews in the same way.

I printed, in real size, a paper template with all the numbers, hour and semi-hour marks that I taped on the equatorial belt, taking into account that the central part of the belt -12 solar time- corresponds to 13:24 h from winter time: 1h for the time zone and 24 min for the 6º W with respect to the Greenwich meridian. I marked with a cutter the positions of the numbers and marks and, after removing the template, I glued them with 2-component adhesive.

The final touches were made by polishing the sundial with an abrasive disc and also manually with sandpaper and file.

I have used brown and orange exterior spray polish and maroon brush polish as seen in the photo below.

A reinforced concrete screed was first made with a wire mesh. Once hardened, it was drilled to place 12 mm rods that were joined with 2 mm wire, to form the reinforcement that has to be covered with cement confined by a polycarbonate mold. The capital, as a decorative element, is a cutted terrazzo tile, which is attached to the fiber sundial and the concrete pillar by means of mounting adhesive.

MEUM ET TUUM TEMPUS NON EST IDEM

I printed the motto on paper and sticked it on a piece of blackboard. I engraved the text with a Dremel and glued the board with two-component adhesive on the base of the sundial.

Once the watch is glued on the capital, I put the assembly on the pillar and made small adjustments of rotation and transversal inclination so that the marked time is correct, taking into account the correction of the time equation. The assembly was attached with mounting adhesive.

April 2021