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Originally Posted by beaver74 if you want to drill a hole for a 4" you will want a 110mm core drill as core drills sizes are out side size and any pipe is sized 4"inside dimentions |
If you have a choice, get a "thinwall" core bit (as opposed to thickwall) if you're just coring the hole in brick and block. Much less effort, quicker, and easier on the drill motor. I tend to core slightly bigger than 4" to accomodate screw heads, duct strapping, etc, that might also have to slide back in the hole as an assembly with the damper cap. If you drill a hole "exactly right", you'll end up cursing yourself. Most of the damper caps will cover up to a 5" hole.
Some of my friends have had decent luck with the grit-type hole saws in brick and block, but for just a few dollars more you can get a proper carbide toothed core bit. Difference between toys and tools.