Wanted to share my fluting technique which works for me. This probably hasalready been tried. After getting the flange to 90 degrees with the rib, I clamp the rib to the table so that the flange I want to work on is up. Then I clamp my straight edge to one of the end holes along the top flange(the one that I want to straighten). I hold the other end of the staight edge in one hand and the fluting pliers in the other. I start in the middle and can flute and actually watch the rib holes form a straight line with the straight edge. If anyone wants a picture I post one. Hope this will help other new builders.
Please post pictures