Sunshine Recorder, Keeping Track of the Time That the Sun Is Shining

A sunshine recorder is like the opposit of a regular sundial. You see a bright spot instead of a shadow spot. The solid sphere is like a lens, creating a tiny image of the sun in the focalpoint of the sphere. This focal point moves around during the day just like the shadow would of a regular sundial. This model is based on the classical Campbell Stokes sunshine recorder. (picture from Wikipedia)

A strip of paper is held at the right distance halfway around the sphere. Any moment the sun shines, a hole is burned into the paper. After a day outside, the paper strips is a recording of the time the sun was shone brightly during the day.

The paper strip has an indicator showing at witch time the sun was shining.

In a sense it is a recorder of time.

This type of recorder has been used by weatherstations aroud the globe for more then 100 years. Now mostly obsolete and replaced by electronic devices.

The key-part is a solid glass sphere available at web stores. I found many between 10 - 20 $. I bought an 80mm witch was actually 78 mm and a 70 mm sphere that measures 68 mm. I designed 3D printing models for each. They work equally well. The smaller ons has the options of adjusting for local latitude. The larger one is fine at approx. 40 to 60 degrees of latitude.

Find your glass ball at a web store you trust best. If your ball turns out to be slightly larger or smaller, you can scale all the 3D-printing parts accordingly.

A nice extra feature is to add a magnetic compass. This will make setting up your recorder a lot easier.

The Tinkercad design is public domain.

Link for 78 mm glass ball:

Link for 68 mm glassball:

Print all the parts in PLA-filament. (some parts need to be printed twice) The frame needs to be sturdy, put your top/bottom&wall height at 2mm, layer height 0,2 mm.

After printing it is fairly obvious how the parts fit together. The hardest part is the paperstrip holder. These three pieces are glued together (super-glue / cyanoacrylate).

It is crucial to add a strip of solid aluminium tape. The first time I didn't, and the sun burned through all the layers of plastic!

Place a strip of paper just wide enough to fit in the side grooves. I have added a pdf file for the paper strip.

Apperently the aluminium also functions as aa heatsink. I have not seen the paper catching fire (yet).

When setting up the recorder, place it facing exactly south (Northern hemisphere, Kiwi's and the like do the opposit)

At your location it is unlikely that the paper strip time marker at 12,00 h will match. The timezone time is not the same as the local "sun-time". Slide the paper left or right until the paper matches your local time.

Adjust the angle of the ball holder according to your latitude. And adjust the paper-holder according to the time of the year. (Low in the summer when the sun is highest). It might take a few days of trial and error to get the scorching right in the middle of the recording paper.

Have fun building and using you Sunshine Recorder

(let me know of any improvements)