Hi all.
I want to build a frame for an double glazed window which will
hinged at the top for opening.
The dimensions of the frame wil be about 81cm wide by 50cm high and will be
made
from sapele/mahogany,
So what size of section should I use?

Thanks.

Arthur

There is no "correct" size. Assuming your glazing units are 4/16/4 (a
common size) plus a further 20mm for the glazing bead, that's a 44mm
deep rebate, so you might use something like 75*50mm section for your
opener. Frame depends on whether you go for a flush opener, or some
other pattern. It may make sense to match it to the original for
easier installation and making good.