The frame insert is made from 1/4 thick by 4 inch mild steel welded together. It drops down into the base and I drilled and tapped the base for 4 3/8 bolts to secure it. I will use some aluminum tape to seal up a few small gaps while the epoxy hardens. You can see I boxed around the bays where my column attach bolts go so no mix goes in those areas. I want to keep access the that area. I got rid of the original column bolts and now have grade 8 bolts that go in from the bottom. They first go through a 6 inch long by 3/4 thick , 1.5 inch wide steel bar that is secured to the base with two 1/2-13 setscrews tapped through the plate and the base and also a flushhead 3/8 bolt from the top with a nut on the bottom.