The dividers were prepared with double tenons on the ends that would go into the frame, and a single tenon where the dividers intersect.
I could clearly see progress in the appearance of the tenons when comparing the first set and the last set of the dividers. I think that the last ones actually looked quite good.
The problem with tenons is that they need a mortise.
I am not very good at making mortises by hand, but I had decided that I didn't want to fire up the mortising machine for this project. So I drilled out the majority of the waste using my crappy Forstner drills and cleaned up the rest with some chisels. The mortises were nice and tight, but I just don't think they look very good on the inside. Actually it shouldn't bother me, since they will have a glued in tenon, so it will probably never show anyway.
All the edges were chamfered before gluing up the window. I have a nice Japanese chamfer plane that my little brother gave to me for a Christmas present some years ago. It works brilliantly.
I had tested the individual joints after finishing, so theoretically it should all go together without any problems.
Whenever I have a glue up like this: 4 dovetailed corners, 4 double tenons with corresponding mortises and 2 single tenons with mortises - I am kind of intimidated.
I get a feeling like the first time I took my drivers license. You know that it should be all right. But you are not completely sure anyway.
I added glue to the various joints using a small acid brush, and miraculously it all went together and the diagonal measurements were within 1/16". Apparently I must have done something right.
The mortises were made with a slight slop outwards, so I could wedge the tenons once assembled. Each tenon received two wedges. I used a method described in Woodworking Magazine, where they suggested that you merely split the end of the tenon using a chisel. After that the wedge should be hammered in place using some glue. The theory is that the split will follow the grain of the wood instead of a sawn kerf that will go where you put it.
As an answer to a recent question regarding if I could take out the extra layer of bricks, I have attached some photos of the windows in this part of the machinery shed. There are a total of 8 windows that have all been remodelled with extra bricks. I think it would look strange if only one window was lowered to the original height.
Making a double tenon.
All the pieces laid out.
Glued up and wedged (and square).
The front of the Japanese chamfer plane.
The window from the inside.
Two more windows (the original cast iron stable type).