How to build a wooden wishing well
The Gap Equation
The distance of the gap between the palings is crucial to forming a good circle. The gap, or spacing between the palings (a) should be the thickness of the wall board divided by 2.6.
For example: The thickness of the palings in this project is 25mm (1").
Therefore: 25mm (1") divided by 2.6 = 9.6mm or near enough to 10mm (3/8"). Hence the gap or spacings between the palings in this project will be 10mm (3/8").
Note: The width of the wall paling has no bearing on the size of the gap. Whether the palings are 100mm x 25mm (1x4) or 200x25 (1x8), the gap will be the same. Only the thickness and the total number of palings matter. 14 palings (a) and 2 extended palings (b) make 16 palings in all. Each paling is at a 22.5 degree angle to the next, and 22.5 degrees times 16 is 360 degrees, which is a circle. Get it? Yep!
Note: The above formula will only work if the corners of the boards are square. If the corners are rounded the equation will not work.
Cross-section of the palings.
But, there is a way you can use lumber with rounded corners, as explained on the next page.