July 12, 2026
Description
This design is loosely based on the Scottish Ilay Glynne sundial, a mechanical standing equinoctial ring dial which utilizes an integrated clock face with hour & minute hands. The Ilay Glynne dial was made around 1715 by Richard Glynne, a successful and well-regarded maker of mathematical instruments, and is the most important surviving example of his work. It was used to measure local time from the Sun, providing the most accurate means of setting clocks available at the time. It was commissioned by and belonged to Archibald Campbell, Earl of Ilay and later 3rd Duke of Argyll (1682-1761), who was a hugely influential figure in post-Union Scotland.
In a typical sundial, the time reading accuracy is a function of sundial type, design, size, construction, assembly inaccuracies, etc. This sundial compensates for most errors by utilizing a planetary gear system, which is coupled to the Alidade, Nodus & Analemma components of this uniquely styled heliochronometer sundial design. The sun's shadow is aligned onto the Analemma plate by rotating a knob located under the main hour dial plate. Once aligned, the minutes are easily displayed on a secondary dial. This is achieved using gears of an appropriate ratio such that 1 hour movement on the main dial equates to 1 full rotation of the secondary minute dial, or 60 minutes. The Alidade, Nodus & Analemma assembly rotates around the main hour dial as the minute dial rotates independently, displaying the minutes of the hour. The minute dial rotates a total of 24 times in 24 hours, or for every complete rotation of the Alidade assembly around the main dial plate. The design results in an hour-by-hour, minute-by-minute movement synchronized to the sun's position. No complicated tick mark arithmetic is required anymore to tell the time to within a 1-minute accuracy!
Please note that this design is meant to be used in the northern hemisphere. If you are interested in a southern-hemisphere design, please refer to this Printable to download the additional parts: Heliochronometer Clock Hybrid Sundial for Southern Hemisphere by 3DMason | Download free STL model | Printables.com
Planetary Geared 0 to 60 Minute Secondary Time Scale Dial with a 1 minute reading resolution, consisting of a sun gear & two planetary gears traveling around an outer ring gear located under the main dial plate;
A tilt-adjustable Nodus within a curved vertical arm for Sun Elevation Compensation throughout the year. This feature enables a sharper shadow to be cast against the Analemma plate, especially at the elevation extremes;
A 25% Larger Curved Analemma Plate for improved reading accuracy;
A Simplified Design of the Primary Time Scale Dial with a 1-hour reading resolution;
Time readings are accurate to < 1 minute throughout the entire solar year from any location in the northern or southern hemispheres. In practical terms, however, the accuracy will always be determined by the quality of its construction, assembly and precision of its final alignment;
Displays Local Mean solar time directly by computing corrections to the true or apparent solar time. It achieves this by utilizing a visual-mechanical computer, also known as an Analemma plate;
Converts Local Mean Time to Standard Local Time via meridian offset dial adjustments of ± 1-¾ hours, with 5-minute reading resolution;
Also compensates for Daylight Saving Time using the same meridian offset dial;
The time is “tuned in” by turning a knob located under the main hour dial. Rotating the knob moves the entire Alidade, Nodus & Analemma assembly, which enables the precise positioning of the sun's shadow against the Analemma vertical plate. The time is then read from the main hour & minute dials;
Adjustable Latitude Scale Dial with 1-degree reading resolution;
4 base options are available: 3 with integrated magnetic compass and levels, and 1 without. For compass/level options, refer to these printable links:
Assembly measures 180 x 200 x 200 mm (W x L x H).
This heliochronometer was constructed out of ABS plastic filament.
For definitions on the various parts that make up a heliochronometer sundial, see my other Printable at: Heliochronometer - World's Most Accurate Sundial by yba2cuo3 | Download free STL model | Printables.com
The spacing between the Nodus & Analemma vertical arms was increased to 100mm, or 20mm greater than my original 80mm design. This spacing increase results in a 25% dimensional increase of the Analemma Curve, therefore increasing the overall reading resolution by an equal amount.
The larger Analemma curve was calculated & designed using the instructions from one of my other Printables designs, which utilizes several Python scripts within Blender. Check out How a Curved Analemma Plate was Designed into this Heliochronometer from: Curved Analemma Plate for a Heliochronometer Sundial by yba2cuo3 | Download free STL model | Printables.com
The Nodus was modified to add a tilt feature & the original flat vertical arm was converted to a curved design. Therefore, the Nodus elevation can now be adjusted to match the sun's height above the horizon during the course of the year. This results in a sharper sun projection cast against the Analemma plate, which also helps with the reading resolution.
The mounting locations for the vertical arms on the original Alidade remain unchanged from my original heliochronometer designs, which means that the larger curved plate Nodus & Analemma designs presented here can be used on my other heliochronometer designs without any additional modifications i.e.
Both hour & minute dials were generated using an online template design tool; i.e., Clock Face Templates - Metric + Inch. The SVG drawing was then imported into Inkscape & then modified/enhanced for Blender. Once imported into Blender, a thickness was assigned to each dial & then saved as an STL.
Common:
Pressure Angle: 20 degrees;
Module: 1;
Backlash: 0mm;
Root Filet Radius: 0.5mm.
2 Planet Gears with Carrier:
69 teeth;
69m Pitch Dia.
Sun Gear:
6 teeth;
6mm Pitch Dia.
Outer Ring:
144 inner teeth;
144mm Pitch Dia.
Printer brand: Prusa
Model: MK4S
Supports: Yes, on some of the parts which are flagged in your slicer app
Resolution: 0.15mm & 0.2mm on the larger parts
Infill: 20%
Brim: Yes, on some of the larger parts, if you use ABS
Filament brand: Doesn't matter
Filament material: ABS, but OK to use other material like PETG or ASA
Filament color: Doesn't matter
Special Notes:
Print in an enclosure for best results.
There are a number of approaches to highlighting text on printed surfaces. Two print options are presented in this design: (A) Debossed or Embossed Single-Part Object; or (B) Separate 2 Part Solution.
(A) Deboss or Emboss Single Part Object:
The traditional method is to deboss (engrave) or emboss (raise) the text & numbers, etc., onto a single part and then use a slicer program to change the filament color at a specific height, either below (engrave) or above (raise) the main surface. Pros: simple & durable with no post-processing. Cons: Any (lighter color) on the main surfaces may darken due to the (darker) deboss colors “bleeding” through; however, this would not be an issue with emboss;
Another option is to print a debossed part in one color, then fill in the debossed area with a filler like Markal B Paintstik Paint Pencil, followed by wiping off the excess with a dry cloth, then with a bit of Isopropyl Alcohol to remove any “staining” remaining on the main surface. Pros: Simple & Effective. Cons: Messy & not as durable outdoors. See this article for an explanation of the procedure: Labeling Your Parts with Engraver Filler;
Paint the entire top surface of the deboss area, then sand off the excess paint from the main surface. Pros: Durable. Cons: Messy & labor-intensive. It may also remove some of the finer print details due to mechanical abrasion.
(B) Separate 2 Part Object (no deboss or emboss):
The best approach is to have letters and numbers, etc., as separate objects and brought in as equal heights to the main surface, which can then be printed in different colors. Separate objects create cleaner & clearer boundaries. If you are looking for more details, the technique is clearly described here: http://3dfaq.net/03_designing_for_3d_printing/01_multi_colour
There is also a faceplate design example using Fusion 360, which further illustrates the principle: https://www.printables.com/model/1040553-sundial-faceplate
2 Part Object Import using PrusaSlicer
If you use PrusaSlicer, there is no need to align or center the parts after importing. They will come in at the correct superimposed positions. Here is the procedure:
Import Part A (main body) 1st. The part will center on the bed;
Under Editing, left-click the icon next to Part A, then add part & load, then choose Part B (text & numbers). Re-center Part B over Part A. Both parts will now be aligned in the 3D viewer.
You can then use the Multi-Material Painting feature following this guide: Multi material painting | Prusa Knowledge Base
The construction of this sundial is relatively simple, making use of M2 & M4 Stainless Steel Button or Cap Head Screws and Nuts. A list of assembly materials is provided along with where they're used. All parts can be easily disassembled and reassembled to facilitate transportation. See the file section for Planetary Geared Sundial-Clock Hybrid Assembly Instructions.
Magnetic Compass
Circular Bubble Level
Alternatives: Smart phone with: 1) Compass or GPS app, 2) level app.
Before using, make sure that:
Your sundial is perfectly level;
Your latitude is set on the latitude scale;
Your sundial is pointing to true north.
Update (01-04-25): For alignment procedures, adjustments for time zone meridian offsets & daylight savings time, etc., refer to the attached file named: How_to_Setup_your_Heliochronometer_Clock_Hybrid_Sundial-Detailed-Instructions-v1
Simply turn the dial knob located at the bottom of the main sundial plate to rotate the Alidade until the light through the Nodus hole is aligned onto the dark curve on the vertical Analemma plate. Ensure that you are on the correct portion of the Analemma curve, which corresponds to the current month of the year. Do not try to move the Alidade from the Nodus or Analemma vertical arms, as you will end up damaging the gear system. Only use the knob to move the alidade/nodus/analemma assembly. The hour will be displayed on the main hour dial & the minutes on the secondary minute dial. That simple!
If you think this is a cool design, don't forget to hit the like button. I hope you enjoy building this design & thanks for your support!
Gard Heliochronometer Sundial Derivative by yba2cuo3 | Download free STL model | Printables.com
Sundials - Their Construction & Use, R. Newton Mayall & Margaret Mayall, Dover Publications Inc., 1994
The Equation of Time: The Equation of Time
License:
Creative Commons — Attribution — Noncommercial — Share Alike
3DMason
