My plan was to cut one blade with a snail a bit small, then use it to cut a slightly bigger snail in the other disc (my plasma cutter tip is 1/2 inch from the edges of the "standoff" so the second snail will be a 1/2 inch bigger if I trace around the first snail.) This would give a 2-bevel edge, similar to the fancy Fiskars splitting axes, which I'm hoping will cause the chunks to split themselves with the grain as it's being cut.
I'm curious, could I use my mild-steel MIG welder to join those discs near the second bevel/edge?
I also have a smaller piece of 1/4 inch steel plate that I'm going to bolt to the outside surface to help with rigidity and act like a "washer" for the bolts.
I got them from the scrap pile of an equipment rental place. I think they're made to cut concrete like these...