Sundial layouts, computed & drawn for the cutting machine

Fig. 1. A horizontal dial, 300 mm square, for Greenwich, 51°28′ N. The lines allow for longitude; the curves are the solstices and the equinox, with the noon analemma, all traced by the shadow of a nodus 35 mm high. A demonstration plate drawn by Hourline.

Decimal degrees, south negative. Fig. 1 and the angle tables below are recomputed in your browser; nothing is sent anywhere.

Hourline lays out sundials for the people who make them. Say where the dial will stand, which way its wall faces and how big the plate is. Hourline works out every hour line, the gnomon and the date curves, and hands them over as clean vector files for a laser, router, plasma table, waterjet or engraving machine.

You could do it with a protractor and a book of tables. But modern dials are cut by machine, often for a customer's own garden, and often for a wall that doesn't face due south. Correcting for that wall, for longitude, for the time zone and for the thickness of the gnomon is where afternoons go and where home-made dials go wrong.

  1. Horizontal dials for any latitude, rectangular or round, northern or southern hemisphere.
  2. Vertical dials on any wall, declining ones included, and the parallel-line dials an east or west wall demands.
  3. Armillary bands, unrolled flat with every hour, half and quarter marked.
  4. Longitude and time zone built into the lines, so the dial agrees with the clock but for the equation of time, which is tabulated for each plate.
  5. Date curves and the noon analemma for dials with a nodus.
  6. Gnomon template with mounting tab, and morning and afternoon lines split for the gnomon's thickness.
  7. Single-stroke lettering throughout: numerals, motto and coordinates engrave as clean lines, with no fonts to install or convert.

Open the workbench

Designing, the tables and a full-size paper proof cost nothing. Cutting files are $14 a plate, or a Workshop Licence for makers who sell their dials.

§1Hour-line angles for 51.48° N

The classic table, free and computed for you: the angle of each hour line from the noon line at the root of the gnomon, for local sun time. The workbench does the rest, including the longitude, the time zone, the wall and the plate.

§2For whom

Makers who sell personalised dials. The garden sundial engraved with a family name and a house's coordinates is a steady seller. It is only honest if it is laid out for that house. Hourline makes each order a new set of files in a few minutes rather than an evening with a calculator. The Workshop Licence covers selling what you cut.

Stone carvers and letter cutters. A full-size tiled print to transfer onto slate or stone, with the gnomon dimensions and a correction table to cut on the plinth.

Blacksmiths and metalworkers. DXF for plasma and waterjet, with the gnomon as its own part.

Restorers, architects and builders putting a dial back on a church, school or house wall that faces nobody-knows-where. The declinometer finds the wall's true direction from one sunny moment.

§3What arrives in the file

CUT
Plate outline and gnomon outline, pure red in SVG for laser cutting.
ENGRAVE
Hour, half and quarter lines, chapter rings, date curves, analemma, and all lettering as single strokes.
GUIDE
Gnomon footprint, style root, nodus foot and fold line, in blue. For setting out, not cutting.

Everything is drawn at true size in millimetres. Before you spend anything, download a specimen SVG or DXF and open it in your own software.