I thought I'd just go to the hardware store and pick up a few pipe
clamps and I'd be done. However, it seems that no standard pipe or
tube actually has an OD of 1.25", so nothing in either the electrical
or plumbing sections will actually work.


I am puzzled that you could not find a clamp that would fit your
mast. The electrical dept. should have U clamps, and single screw
conduit clamps, some at least which should provide a reasonable fit
over your mast. If you must, get the size which may seem too small and
either use spacers between the clamp base and wood, or simply screw the
screws in tight even if the clamp base doesn't press fully against the
wood as you might prefer.


Also, you might want to screw a bit of 2x4 to the fence cross piece
in such a manner as to provide a base on which the mast can set....
otherwise it might be possible for it to slide down in the mounting
clamps you use.


Good luck.

Ed K7AAT