Alright guys so as a lot of people know I am going through a lot of work to fabricate SFCs. Anyway where the bolt holes go that bolt stage 2 to stage 1 I want to put sleeves in the flat ends of the stage 2 tubing and in the tabs so the bolt holes dont expand because I'm using mild steel for the SFCs. Basically I am going to be welding in a rollerblade bearing sized solid steel sleeve into the tab and into the flatened ends of the stage 2 tubing. Each of the sleeves on the tabs will be slightly concave in shape and the sleeves on the flattened ends of the tubing will be slightly convex, so one will fit inside the other and a bolt will hold them together. Taking the shearing forces off the bolt its self, the bolt then will only be holding the 2 sleeves together.

This is a diagram of the cone like shape that will fit in the other matching cone shape. This diagram shows the cylinder being very long but in reality it will only be about 1/4" to 3/8th" deep with the convex piece also being that deep. The diameter of the jackets will be about 3/4" - 1" . The diameter of the bolt hole going through the center is still undetermined I dont know how thick to make the bolt. Obviously this diagram is not in the right scale, but you get an idea of what I am going for.



Anyway I am looking for a piece already produced that is similar to this. Maybe a part already has this convex/concave shape and I could get a machinist to drill out the center to the right bolt hole size, and cut it to the right height. Basically I am checking to see if there is any part that you guys know of thats already made thats like this part that would be easier to modify than to create totally custom.

Let me know
Thanks,
Josh