Deburred rib blank, sandwiched between form blocks and clamped in vice with extra C-clamp to hold narrow end of form blocks.
Reference: During my stint as quality engineer at GM I made a couple of trips to a vendor in Ohio where we had moved (i.e. re-sourced form our internal stamping/assembly plants) several past-model service sheet metal assemblies. The process being used to hem the outer skin of a door to it's mating inner panel consisited of a robot programed to pass around the perimeter with a pneumatically powered "hammer", producting unacceptable results. The robot was re-programed to make several passes with a bending tool that gradually, evenly formed a hem that looked and measured just like the doors from OE dies.
Rather than using mallet to pound down a straight edge - like the hammering robot - I used a flat piece of MDF to evenly bend each flange without introducing any stretch which would result in waviness. Used mallet to tighten up the bend along bend radius. Much faster with better results.
