The top bars of Langstroth bee hive frames require the trickiest cuts. Follow these steps and refer to the following figure to make these cuts.
Cut a kerf 1/8 inch wide by 5/16 inch deep along the entire long length of the designated underside of the top bar.
Cut a vertical notch 3/8 inch wide by 3/32 inch deep on both sides and at each end of the top bar.
The notch starts 5/8 inch back from the ends of the bar. When you assemble the frames, you insert the top of the side bars into these notches.
On the underside of each end of the bar, make a 1 inch wide by 3/8 inch deep rabbet.
This creates the tabs at each end of the top bar.
Cut a kerf 1/8 inch wide by 9/16 inch deep along the entire long length of one of the vertical sides of the top bar.
Position the cut 3/8 inch down from the top of the bar. Save the resulting strip of wood. This piece is not scrap — it becomes the wedge bar that you'll use later on when you install foundation.
Credit: Illustration by Felix Freudzon, Freudzon Design