Side bars for your Langstroth hive frames have a wide profile at the top and taper to a more narrow profile at the bottom. This tapered shape provides the correct distance between frames and allows for the proper bee space around and in between the frames so that bees can travel freely (and so they won't glue the frames together).
Each end bar has a notch at the top to accommodate the top bar and a notch at the bottom to accommodate the bottom bar. Follow these steps and refer to the following figure to make the cuts for side bars. The basic steps are identical for deep, medium, and shallow side bars. Make these cuts using your table saw or a table router if you have one.
It's easiest to make frames assembly-line fashion — set up your work space for making one particular cut and then repetitively make that cut on all the pieces that call for it. For example, cut out all the top notches on all the side bars before readjusting your tools and measurements and moving on to the bottom notches.
Create the taper by removing 3/16 inch of material from each vertical edge of the bar.
Note that the lower portion of the side bar is more narrow than the upper portion. Refer to the call-outs on the figure to determine where to begin the taper.
Cut a notch 7/8 inch wide by 7/16 inch deep at the top of the bar.
The top bar will snap into this notch when you assemble the frame.
Cut a notch 3/4 inch wide by 3/8 inch deep at the bottom of the bar.
The bottom bar will snap into this notch when you assemble the frame.
Credit: Illustration by Felix Freudzon, Freudzon Design