Golden Section or Golden Mean Gauge

I have been reading the excellent book By Hand And Eye by Jim Tolpin and George R. Walker recently.
For those of you how might not have read this yet it "introduces us to the language of pre-industrial artisans" and "how period work is based upon how we relate to our own bodies and the world around us in terms of proportion, ratio and scale". It really is an interesting read and I encourage people to have a look at it.

I was speaking to a friend the other day and she mentioned the "Golden Ratio" and "Fibonacci Numbers"
I know from my time in engineering that when something "looks right" it invariably is right. It turns out that since ancient times people having been making use of the "Golden Ration" to design furniture, bridges, buildings so that they are pleasing to the eye.
With this in mind I decided to have a look for some plans to make a Golden Section Gauge. There are many about and some you have to pay for. I found a website where there were already PDFs showing the dimensions required. They are in mm but you can convert them to inches if desired by dividing by 25.4

I set to making mine from some scrap mahogany 5mm thick. I cut them to width of 13mm (1/2") and to the lengths quoted on the PDFs. I then rounded off where required and cut points where required. I also carefully marked out the holes and drilled - the longer pieces were drilled as a matching pair.

I pore filled, rubbed down to 320 grit and then coated with some shellac. Once dried I then gave it 3 coats of Arm-R-Seal.
The pivot points are secured with stainless steel socket screws with washers between all parts and a nyloc self locking nut.

When the gauge is adjusted the middle arm will always show the golden section or phi point between the two outer arms. Set your calipers to this point and you can mark off the golden ratio (or multiples of) onto your work.

Golden gauge components

Golden gauge assembled