Drilling 16mm hole in concrete: pilot hole?

[jerrytug]

I am a bit inexperienced in masonry drilling, and I have to drill a 16mm hole upwards into a concrete ceiling, for an M10 expanding eye-bolt to hang a hammock seat from.
Should I use a pilot drill before going up to 16 mil? I would have thought, yes obviously you should use a pilot drill.
But I have only one chance to get it right first time, so I though I would ask. Thanks

 

[Munkul]

No. The bigger drill will snatch and it will be annoying and possibly break something. A 16mm masonry drill will work first time every time. Unless it breaks (unlikely)

 

[123hotchef]

I would just go straight in with the 16mm, if it is hard concrete you could make a small divot so the 16mm dont move about

 

[Munkul]

The more concerning thing to me would be the eye bolt, some concrete is variable and the bolt may or may not work. What works every time is resin. Amazing stuff, I would never be without it, and any hole I'm suspicious of I'll use resin with regular anchor bolts.

 

[Onoff]

Just hope you don't hit rebar!

At a push you could stop drilling with the masonary bit if you do and take out the rebar with a 16mm Starrett holesaw.

 

[JMS1972]

I'd suggest using an SDS drill if you can. It will make light work of concrete....

 

[Maker]

I've never drilled a pilot for masonry, I've read online that you should though. Don't think it needs it, a masonry drill "cuts" along its whole edge.

 

[Onoff]

I'd suggest using an SDS drill if you can. It will make light work of concrete....

I've one, single, Hilti rebar bit from years ago somewhere...never used it.

 

[Dcal]

Got to agree with @Munkul on the resin, however even a thunder bolt will be better than an expanding bolt.

 

[Brad93]

Never drill a pilot

 

[Onoff]

Read my tale of woe when I piloted and ruined a couple of 1m long SDS bits recently!

SDS Bit Stuck In Concrete

Trying to drill a 65mm hole (for a duct) down through my garage floor at about 45deg. So through the concrete, engineering bricks then down through the concrete footings. Got so far with a Mexco SDS core cutter. Not tbh really meant for concrete but had the hole filled with water to keep...

www.mig-welding.co.uk

 

[jerrytug]

Thanks chaps. We will go straight in with the 16mm bit, and be ready to reposition a few inches if the drill bit hits rebar.
A resin question: yes it's better than expanding 'brick splitters' but I have never used it in a vertical hole, won't it just ooze out?

 

[Dcal]

No
What size fixing do you need?
The hole I'd usually 2 or 3mm bigger than the fixing.

 

[123hotchef]

Thanks chaps. We will go straight in with the 16mm bit, and be ready to reposition a few inches if the drill bit hits rebar.
A resin question: yes it's better than expanding 'brick splitters' but I have never used it in a vertical hole, won't it just ooze out?

no the bolt will hold it in its not so runny

 

[roblane65]

If your going to use resin make sure you blow the hole properly or the resin is just sticking to dust

 

[Munkul]

Good sds bits go straight through rebar

 

[Onoff]

Good sds bits go straight through rebar

Lidl ones don't...

 

[The_Yellow_Ardvark]

No need. But if the surface is a bit rough, a 8mm to make a smnall pit for the 16mm tip to sit in will not go amis.

Travis Perkins Resin kit or resin anchors is not a bad bit of kit if you want to go resin fixings.

 

[Ton-up]

What do you mean by 'concrete ceiling'? Is it proper reinforced concrete or beam and block? if proper concrete then as others have said, straight in with 16mm. If its other types of crumbly concrete, I would probably use a pilot.

 

[mike os]

Lidl ones don't...

he said good