To make the mounting disc:
Find the center of balance of the cutting board by balancing it on a knife or scribe and mark it.
Using a compass, draw a 10cm circle from the center.
Set the compass to 11.75 cm. divide the circle into 5 sub-divisions by setting the point on the edge of the circle and marking where the lead point crosses the circle. Some trial and error required to get it perfect. (see attached)
Drill the center for 1/2" hole
Using the plates supplied with the 2 1/2" clamps, mark & drill the 1/4" mounting holes for the clamps (refer to hub pictures)
loosely attach the u-clamps to the disc.
Place a fender washer on the bearing, then the board, another fender washer, split lockwasher, nut and tighten.
The hub is complete.