I completed vertical channels number 3 and started to work on vertical channels number 4. To create the small 1/4 inch radius I made two cuts with the andy snips in from the edge of the flange. I then used needle nose pliers to bend the tab until it broke off. Once the notch was created I put the channel in a vice and used a small round file to create the radius. I finished the notches using the andy snips.