To make the iron support, Paul makes two cuts in a rectangular piece of wood in such a way that those two cuts are perpendicular to each other with the iron side at 50° to the base.
Tobias Bauer was questioning this (as I was).
Starting with a squared piece of wood with a section of at least 33 mm X 39 mm, one cut first the iron housing dado on the 33 mm side; then make a single cut following the line 7 on my drawing.
while I think all is just fine with Paul’s approach, I was curious how it would work with a single cut at 50° from square stock, rather than two cuts.
It works very well, ideally take a squared stock of about 44x35mm (1 3/4″ x 1 3/8″). While the length of the 2 top sides will be less than 44mm (which will be the size of the base), it’s easier to work with a little oversize.
1) Cut the groove into the 35mm side.
2) Set a 50° angle to your sliding bevel and mark the cut for the base size in that position so your base will be 44mm long. Extend the marks all around the work-piece.
3) You can easily cut this in the vise, staying away from your line, and then plane down by using a clamp in the vise just as Paul shows.
This worked very well for me, and it’s quite easy to mark the groove side and ends all the way. It also helps to prevent any breaking off of the groove’s walls.