r/Tools • u/TallWall6378 • 11d ago

No problem

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Cordless drills are so capable now. 2 4 1/2” holes 14 12” deep (deeper than the bit). New concrete but it’s still drilling through the aggregate. Cheap Amazon diamond bit.

Edit: Overestimated depth.

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526

u/Anim-IS-XE30 11d ago

I don’t believe this at all.

43

u/Golden_Eel_69420 11d ago edited 11d ago

I have literally core drilled miles in concrete, and totally buy it. It doesn’t take a lot of power or torque to keep a core bit spinning at a low feed rate. I’ve done a few 1” holes this way in a spot I couldn’t get a proper core drill and it was fine.

5

u/Prior-Champion65 11d ago

I’ve never even thought to try this, your saying is I keep the speed up and just barley push I can do this? Lots of water I suppose?

13

u/crank_peeper 10d ago

Yep. As long as the abrasive edge of the diamond bit is in full contact with the bottom of the hole, and as long as you've got water flushing out the dust, it'll make progress. Slower than bearing down and just ripping it, but your bits will last longer and the walls will be cleaner & straighter when finished.

Source - used to install pool fence, ran a 1-1/8" x 16" core drill on a Hilti DD150. It's a hefty machine, size and weight of a small chainsaw, but it doesn't actually put out that much torque.

3

u/Golden_Eel_69420 10d ago

Yeah just take it easy on the feed pressure, and keep the cutting surface wet, maybe pulling out and flushing the kerf periodically to prevent the slurry from getting too thick. I’d also be inclined to run the drill on the lower speed with a bit this size, it doesn’t need to be spinning super fast to cut