Making the rose pattern
To mark out all the circumferences I made a compass in the form of a strip of wood with 7 holes drilled along it. Each hole represented a center point for a particular circumference.
The piece of wood that I used to make the compass was a piece of 1" (25mm) wide x 1/4" (6mm) thick strip of wood 12" (300mm) long.
By sticking a nail through one of the holes in the compass (the strip of wood) and tapping it (the nail) a little way into the mdf board, a required circumference could be drawn by holding a pencil at the end of the wood and turning it in a circle using the nail as the axis point.
For the main circle piece I drew 5 circles, each with the following radius:
● The circle with the 10" (250mm) radius marked the edge of the main circle piece: the cut-off line.
● The circle with the 9 1/4" (230mm) radius marked the ends of the slots.
● The circle with the 9" (225mm) radius marked the points for drilling at the end of the slots where the circle line crossed the radius lines.
● The circle with the 6 13/16" (169mm) radius marked the points for drilling at the beginning of the slots where the circle line crossed the radius lines.
● The circle with the 6 5/8" (165mm) radius marked the beginning of the slots.