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How to drill a 4 inch hole in concrete Answered

The walls at our new place are 6 inch thick concrete (it's an old Naval base) and we needed a few holes for vents. I've hammer-drilled through concrete to sink anchors, but a 4 inch diameter hole is a little intimidating -- until you have the right tool. Here's a few pictures of the right tool. I only watched, so I don't know the finer details, but I thought people would appreciate just seeing the tool. The work flow went something like this: 1) hammer-drill and sink anchor to attach machine to wall 2) turn on machine; insert earplugs 3) wait It took quite a while, and that drilling noise reverberated throughout the whole place!


that thing had to sound like it was being powerd by all the evil, hatered, and crying clowns on the planet!...could be used for an instructable "How to turn your car into a 'swiss-cheese-mobile'"

That's one ginormous drill bit :D My parents installed a child safety fence around their pool -- a similar tool was used to drill the 1" holes for the fence posts. I don't remember the material for the bit -- bit it too was water cooled :)

The probably use the water from the pool :P

Agreed, that is one huge bit.
Do you know what the size is where they don't use a giant drill bit anymore, and just cut out the circle?

"I said 4 CENTIMETERS!" *sigh*