Step 3Dado the top panel
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The vertical divider needs to go from the shelf at the new height drilled in the last step to the top. To avoid any visible hardware for securing the vertical divider, a groove is cut into the underside of the top panel of the cabinet. This groove needs to be 5/8" wide and 3/16" deep to securely hold the extra piece of shelving. I cut the groove with multiple passes on a radial arm saw starting from the rear of the top panel. Since the top panel is 1/2" thick, the blade was set 5/16" up from the work surface. The radial arm saw makes it easy to get a very straight cut. I pulled the blade until the front of the cut was even with the screws holes for the magnetic catch. Once the channel was complete, I used a router to flatten out the front of the groove. A router could be used to cut the entire channel, but that requires a little more prep work to get the straight groove.