I need to drill a hole for a new 40mm shower drain. The bricks are old and have proven quite hard when I’ve drilled holes for rawlplugs. I’ve got an sds drill and understand that I’m not to utilise the hammer option whilst using a core drill. I’d like to go through the 2 courses of bricks from the outside. Can anyone recommend a core bit? I presume a centre pilot drill makes using it easier?

Thanks in advance. Diz.

you really need a decent clutch drill for core drilling but if your not that bothered about the external hole finish then perhaps just get a tungsten core bit which you can use on hammer as it will smash through hard brick much quicker and easier than slowly cutting away with a diamond core bit. Or just put a few 10-16mm holes through with a standard SDS bit and bash / chisel out the centre and make good around the waste pipe.

40mm through brick shouldn’t be a challenge with a diamond core bit. I’d personally pay the cash for that than mess about with drilling + chiselling. You’ll want to check it your drill does have a safety clutch, if not very bad idea for the wrists!
I brought the erbauer diamond core drill kit from screwfix for this job.
If you’re around West Sussex you can borrow mine!

To answer the pilot question; the centre pilot is pretty much essential to start the core bit. The kits come with this so you can start with core bit+Pilot bit fitted, then you knock out the pilot bit and continue with the core. Should be No problem going through both leaves of bricks from one side so long as you stop after the first leaf and empty the core out.
You could buy the pilot + core bit + auger (do they call it an auger?) seperately I guess. I bought the kit cos I wasn’t sure what I needed but now I’ve told you 🙂

Edit: Arbor! Not auger!

I got the erbauer core set from screwfix for a job at work, cost £70 for three core bits and arbors and made some neat 117mm holes in some very solid concrete walls!

My only gripe was the Titan drill I had them attached to. I has a speed control but that seemed to go to pot at high torques. E.g. the core bit was probably intended to work at speed 1, but at 1 the drill would just grind to a halt. Setting it to 3 (of 6) on the other hand worked fine (albeit the drill gearbox gets very hot!).

The way people talked about the clutch I was imagining it being a wrist breaking horrible job, the clutch actually kicks in fairly early on, to the point I did worry that it was the drill at fault, I’ve sprained my wrist with my little makita combi drill before!

The pilot is essential, no way you could start it without it.

And use plenty of water, keeps the dust down and keeps the bit from getting hot.

Just drill through with a long 10mm drill bit through both skins, then from the outside, use a tungsten tipped core bit, carefully for a start, then stick on hammer/drill for the rest, you’ll be through neatly in a couple of minutes.

Goldfish 24 thank you very much for the kind offer and information, however I’m in south Lancashire so looks like I will be visiting Screwfix.

Donks, thisisnotaspoon and blazinsaddles thank you very much for your information.

I’ve always just pepper drilled it using a large standard masonry bit in the ads drill. Quicker than going down to Screwfix and ordering the core drill. Certainly for a 40mm hole anyway. Proper cowboy me 🤠

Don’t know if you’ve done it yet, but if this isn’t going to be a regular task, it’ll be cheaper to hire one for the day.

Hilti DD350 – as successfully employed by those Hatton Garden guys.

tthew that’s a thought!