The topic of opening up the longeron is a recurring one and there seems to be a variety of approaches and varying success. I know that before this step I read a lot of different ways to go about it. The HF hydraulic press seems to be a popular way to go and I have that tool, but ended up doing something different. My opinion is that this approach offered more control and it ended up being really easy. I'm just posting here to add one more data point for future builders approaching this step.
We stuck with using a good strong vice. Instead of the socket in the KAI, we used a 3/4" pipe coupling per the published wisdom of other builders. Alignment of the vice jaws with the angle stock and the coupling is key to getting nice easy bends. The vice jaw pictured is available on amazon, you want the style that will hold a round part horizontally. We put the plastic jaw in place, tightened to capture the coupling, then tacked the coupling down with a silicon bronze tig braze. No flying sockets, no slipping longeron...just easy progressive squeezes down the length.
I also 3D printed a gauge to confirm the deflection but I threw that away before taking a pic. If anyone cares about this part reply or DM and I'll provide the file. Easy enough...it's just the correct angle with a round back and 1 3/4" long to slide along the longeron and get a good visual reference for the angle and taper.
We stuck with using a good strong vice. Instead of the socket in the KAI, we used a 3/4" pipe coupling per the published wisdom of other builders. Alignment of the vice jaws with the angle stock and the coupling is key to getting nice easy bends. The vice jaw pictured is available on amazon, you want the style that will hold a round part horizontally. We put the plastic jaw in place, tightened to capture the coupling, then tacked the coupling down with a silicon bronze tig braze. No flying sockets, no slipping longeron...just easy progressive squeezes down the length.
I also 3D printed a gauge to confirm the deflection but I threw that away before taking a pic. If anyone cares about this part reply or DM and I'll provide the file. Easy enough...it's just the correct angle with a round back and 1 3/4" long to slide along the longeron and get a good visual reference for the angle and taper.