Clean the top of the worktable with a dust brush to remove debris from the worktable.
Place the aluminum channel on the cleaned worktable.
Hook the end of the tape measure on the end of the aluminum channel, pull the tape measure along the aluminum channel and mark location that you need to bend the aluminum channel with the awl.
Place the 45-degree side of the combination square base against the solid side of the aluminum channel, align the edge of the combination square blade with the bend location mark you placed on the aluminum channel and draw a 45-degree line across the channel with the awl.
Flip the combination square around and repeat the previous step to place another 45-degree line across the face of the aluminum channel.
Put on your safety glasses, leather work gloves and face shield.
Attach a .035 abrasive cutting wheel to the four-inch angle grinder.
Lower your face shield, pull the trigger of the angle grinder and lower the spinning abrasive cutoff wheel to one of the 45-degree cut lines that you placed on the surface of the aluminum channel.
Push the abrasive cutoff wheel along the 45-degree cut line to make the first miter cut. Use the same process to cut the 45-degree cut line marked on the face of the aluminum channel.
Set the angle grinder aside and pick up the miter cut aluminum channel.
Place one hand on either side of the miter notch and pull your hands together to place the bend in the aluminum channel.