There are some brilliant tips in this thread, thanks everyone
Benchwayze":fbflxhn6 said:
Want to find the centre of a board’s edge?
Using an Engineers’ 90°/45° square:
Square a pencil-line across the board edge.
Scribe a 45° line from each end of the 90° line.
Where the diagonals cross is dead centre of the board edge.
Set the square or a marking gauge from that mark, to mark the board at other points.
HTH
John
On a similar note, to find the centre with a marking gauge:
Set the gauge to the centre distance by eye
Make a mark (a dot) with the gauge from one edge
Make another mark in line with the first from the opposite edge
Hopefully the two marks should be close together. The exact centre of the board will be the halfway point between the two marks.
Adjust the gauge to suit until the marks from either side meet in the middle.
The human eye is apparently very good at judging where the middle is, which makes this method very quick.