Best practice using rotary hammer

[Yankeefarmer]

The last time I used a rotary hammer to install a condensate line through a concrete foundation, it blasted out a chunk of concrete on the exit side, which I repaired with a concrete patching material. This made me think I should drill the hole in from both sides, like you would do with a spade bit in wood. This could be done by first drilling with a small diameter masonry bit to establish the center line of the hole, then enlarging with the needed size rotary hammer bit from both sides. Is this considered the best way to do it? I searched the web, YouTube, and this forum, but the majority of results were just “the best rotary hammer,” or how to insert the bits and hang on.

 

[WoodsTruck]

If you have good access to both sides that sounds like a good approach to make a tidy opening.

 

[Walkers]

What size hole?

 

[djjsr]

This made me think I should drill the hole in from both sides, like you would do with a spade bit in wood. This could be done by first drilling with a small diameter masonry bit to establish the center line of the hole, then enlarging with the needed size rotary hammer bit from both sides.

Your proposed method works. I've done it.

 

[Yankeefarmer]

What size hole?

About 1-1/16”, for 3/4” conduit

 

[dutchgray]

If you want to avoid breaking out the back and cant drill from both sides, don't push the drill, let the bit float for the last inch or so and let it mostly grind its way through, drilling a small hole first helps as well. Takes more time however.

 

[Walkers]

About 1-1/16”, for 3/4” conduit

A 1” Milwaukee Diamond + bit will make a much cleaner hole, but what you are describing will work fine.

 

[shawhite]

Small pilot followed by larger drill from both sides. This is our practice when drilling concrete utility poles.