I finally fabricated the shackles, here is a sneak preview at my fabrication process. The shackles were made from 2"x3/8" mild steel. Most shackles are made from 1/4" heat-treated steel, let's hope these will be strong enough.
In an effort to line up the holes properly, the plates were stacked on top of each other and marked with a letter to preserve orientation.
I made sure I used a non-symmetric letter and put it on a side to keep the orientation of the plate unique.
The stack was then clamped together in a vice and squared up. The stack was welded together to keep it together during the drilling process.
Pilot holes were drilled to give a 4" center-to-center shackle.
The pilot holes were drilled out to a final 1/2" diameter.
Here is the completed shackle (unpainted) and mount. The shackle bolts are 1/2" gr 8 fine thread with gr 5 steel-cut lock nuts. Note that a curve had to be ground into the top of the shackle to allow it clearance to pivot. I may weld a cross plate/tube between the two shackles, but I want to verify clearance with the spring eye before I do that.
