EarthWindandFire wrote:I went and looked at the core drill at Home Depot. I might have to build a jig to hold the drill steady and straight while drilling. The chimney does have a clay flue liner. I'll try to stop the drill when I hit the clay, then I'll finish the hole in the clay with my Dremel. But, back to original post, which hole location would be best for maintaining strength, especially with so many intersecting mortar lines involved?
Forget the Dremel...diamond core drill will cut through clay liner like butter.
Were you looking at the hand held core drill?
There is another drill w/ a base that gets mounted to surface and works like a drill press to guide the bit...may have to go elsewhere if not at Home Depot.