The Heliochronometer is just what its name implies—a solar chronometer. It is not a toy but an instrument for exact timekeeping as well as education. Forgot your watch at home and no access to power or a cell phone to tell the time? No problems. This heliochronometer displays local mean solar time 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. This sundial design is accurate to within 5 minutes (ver.1) or 1 minute (ver.2) throughout the entire solar year from any location in the northern hemisphere. It is capable of providing longitudinal corrections and can display standard or local times. Once assembled it measures approximately 180x200x200mm (W x L x H).

This heliochronometer was constructed out of ABS plastic filament. The analemma curve was plotted using MS Excel and then scaled to match the size of the heliochronometer. The dial also accommodates Daylight Savings Time (DST) by allowing the rotation of the dial plate. The dial design presented here is for use in the northern hemisphere, however, a southern hemisphere dial plate can be easily generated using an online calculator like this one; https://www.blocklayer.com/sundial-equatorial, or use the attached file. The construction of this sundial is relatively simple, making use of M4 hardware. A list of required assembly hardware is provided below. All parts can be easily disassembled and reassembled to facilitate travel.

Feature List Summary: Ver. 1; Ver. 2
Dial Plate Resolution: 15 mins; 5 mins
Secondary Vernier Scale Resolution: NA; 0-5 mins in increments of ½ min.
Time Reading Accuracy: < 5 mins; < 1 mins
Northern or Southern Hemisphere Compatible: Yes; Yes
Latitude Adjustment Resolution: 1 deg.; 1 deg.
Displays Standard Time: Yes; Yes
Standard Prime Meridian Offset Adjustable: Yes; Yes
Daylight Savings Time Adjustable: Yes; Yes
Various Base Options Available: Yes; Yes
Complexity of Construction & Alignment: Medium; High

For latest v2 files, construction & alignment info check: https://www.printables.com/model/998688-heliochronometer-worlds-most-accurate-sundial

4 base design options are available; 3 with integrated magnetic compass and levels, and 1 without. For compass/level options, refer to these printable links:
Tri-leg: https://www.printables.com/model/1012575-heliochronometer-sundial-mount-for-head-leveling-b
Leveling base & tripod head: https://www.printables.com/model/1012539-improved-heliochronometer-sundial-base-design-with