Mike wrote:
I have this brick/tile stuff that is structural for this build. The
building is 70+ years old. Home Depot has a bit that I can bore
through the brick/tile that is just a hair over 4" OD. I have a
scrap of steel pipe I want to put through the hold to reinforce the
brick/tile after I bore the hole. This steel pipe is about 4.5" OD.
I can rent the bit and drill from Home Depot to make the initial
hole, but still need to increase the hole diameter for the steel
pipe. I thought of using some sort of grinding stone to make the
hole bigger for the steel pipe. Is there a better way to make the
hole or to widen the hole for the pipe?

You could drill a series of smaller holes, close to each other but not
touching, around the perimeter of the circle you want then just knock it
out. That's what I did in a 4" concrete slab when I needed to enlarge a
shower drain. I used a 3/16 bit with holes about 1/2" - .3/4" apart.