Building the Spring Creek Kiln: Calculating the arch

So that I could  construct the arch of the Spring Creek Kiln easily I decided the arch would follow an inverted catenary curve. Kilns of this type are commonly known as catenary arch kilns. To plot the curve I used:

• a large sheet of plywood
• two nails
• a chain
• a can of spray paint

I suspended the chain between two points and adjusted the length until I got the desired depth in the curve (or once inverted, the height of the arch). I then sprayed the chain with  paint so I could mark the curve.

Hanging the chain between two nails to create a catenary curve.