Drill a 25 mm hole in concrete

[4integration]

Hi,

I am going to drill through the house foundation (about 30 cm of concrete) and have ordered an SDS drill for the rotary hammer.
Should I pre-drill with a smaller drill before 25mm or can I go 25mm directly?

 

[ViktorHg]

25 direct works well, just keep in mind that it might break some pieces at the exit hole though.

 

[växelventil]

Hello,

I am going to drill through the house foundation (about 30 cm concrete) and have ordered an SDS drill for the hammer drill.
Should I pre-drill with a smaller drill before 25mm or can I go with 25mm directly?

Are you going to drill many holes? There probably won't be any major problems except that the drill gets hot if you're going to drill many holes.

 

[cpalm]

Should one pre-drill with a smaller drill bit before using a 25mm or can you go with 25mm directly?

Do not pre-drill when you are drilling with a hammer drill. However, 25 mm in concrete is a bit on the border for what a "normal" SDS+ machine can handle.

 

[imported_Benno]

Rent a Hiilti and it goes like butter.

 

[4integration]

25 directly works well, just be aware that it might damage some at the exit hole

Yes, I had a feeling, will take it easy towards the end.

Are you going to drill many holes? Probably no bigger issues except for the drill getting hot if you are drilling many holes.

No, 2 pieces and no rush so can let it cool down.

Don't pre-drill when you're drilling with a hammer drill. However, 25 mm in concrete is a bit at the limit for what a "normal" SDS+ machine can handle.

Will give it a try.

Rent a Hiilti, and it will go like butter.

Yep, if it fails, that's what I'll do.

 

[Höghus]

If you pre-drill all the way through with a small drill bit, you can drill a few centimeters in from the back where the small drill bit has gone through with the thick drill bit. This way, you avoid breakthrough on the backside. And you can see if the hole ends up where you intended.

/Höghus.