How to build a sturdy picnic table
A bit about the measurements
The measurements throughout this projects are given in both millimeters and inches.
The abbreviation for millimeters is mm and the abbreviation for inches is ".
The metric (mm) measurements are given first, followed by the imperial (inch) measurements in brackets.
Example: 100mm x 50mm (2" x 4").
However, the metric (mm) sizes do not convert exactly to the equivalent imperial (inch) sizes because the measurements are rounded to their respective commonly called sizes.
Example: A piece of 2" x 4" wood in North America is the equivalent of a piece of 100mm x 50mm wood in Australasia.
2" x 4" is not exactly the same size as 100mm x 50mm.
In fact, if 2" x 4" was converted into millimeters exactly it would be 101.6mm x 50.8 mm, and nobody really wants to be calling those sorts of sizes..
Also note that in North America the narrower side of the wood is called first (2 x 4), where as in Australasia the wider side is called first (100 x 50).
When the same piece of wood is made smooth (surfaced, dressed, planed), there is an even bigger discrepancy. 1 1/2" x 3 1/2" in North America compared to 90mm x 45mm in Australasia.
A project built using metric measurements will be approximately 1.6% smaller than the same project built using imperial (ft and in) measurements.
In this project the imperial measurements are suited to North America. The metric measurements are more suited to Australasia.