I'm surprised that no one has yet mentioned (unless I missed it) the old
trick of using a ruler, selecting a number of arbitrary evenly spaced
markings corresponding to the number of holes needed, then angling
the ruler diagonally across the workpiece (or on a bench where the
workpiece is laying, if necessary) until lines drawn perpendicular to a line
parallel to the holes match up with the selected ruler marks. No
math or arithmetic necessary. Unfortunately easier shown than explained,
but some older woodworking books have pictures of the technique.





--
Better to be stuck up in a tree than tied to one.

Larry Wasserman - Baltimore Maryland - lwasserm(a)sdf. lonestar.org