Core drill

[asalcedo]

I need to drill several 105 mm diameter holes in the walls of a basement for ventilation.

The walls are mainly made of hollow cement block. A few holes will have to be made in brick wall and one even has a ceramic tile on one side.

I have two Dewalt SDS drills, one is SDS plus and one, much bigger SDS Max.

My question is which drill bit and accesories are best for my drills.

Is it dry diamond core the way to go?

Also, how can I use my SDS Max drill?

I would be inclined to use the SDS Max drill but have not seen SDS Max chuck adaptors, only SDS Plus. I know there are SDS Max to SDS Plus adaptors but wonder why the drill sets, like

not come ready for SDS Max drills.

Thanks,

Antonio

[Matty F]

Those are large holes, which would weaken the wall. Would it not be better and easierto drill lots of smaller holes? And they would not allow 105 mm diameter rats to get in :)

[John Rumm]

105mm is not hat large - and will have very little effect on the structural integrity of a traditionally built brick or block wall (unless right under a concentrated load from say a lintel end).

[John Rumm]

I would have thought so...

You can get a SDS Max to SDS plus adaptor, and then use with a standard SDS plus arbour. No need for a chuck as such.

Probably because most dedicated core drills have a conventional jacobs chuck, or many users make do with a "normal" sds class machine.

Chuck adaptors for SDS max do exist:

[Andy Dingley]

I've been using the Aldi dry core drill set (30 quid, bargain!) but using it wet, with the aid of the cat's waterbowl pump and a length of hose. It may or may not be drilling any better, but it's certainly less dusty.

[Jim]

If you're going for the diamond core drills you don't need a huge amount of power, to be honest (they aren't used in hammer mode anyway). You're best off planning to use a drill which you will be able to hold up for the time whilst the drill does its job.

[asalcedo]

No concern about weakening the wall. The walls are not load bearing. They have beams on top that are load bearing.

I remember when drilling a similar diameter hole in the outside brick wall of my London house that the operator used a large drill, I believe it was SDS Max, and still it would get stuck and the clutch would slip. The difference was that that was a solid brick wall. Mine are not solid (except for one).

Based on that experience I would believe that a small SDS Plus drill, and not in hammer mode, would easily get stuck with that diameter core drill.

So, is SDS Max with a dry Diamond core drill at all feasible?

[js.b1]

107mm bit and either SDS drill. If the drill can not get started, hire a Makita Diamond Core Drill, about =A335/day. 107mm is just possible with a crap old 570W drill in solid double brick. You must use a pilot drill in the core drill to get it going and indeed turning it by hand a few times may be necessary to get it to "bite" in the right places and once it is going you are fine. Just watch temperature.

[Matty F]

My bricks are 75 mm high, i.e. much smaller than the hole.

[js.b1]

I take it you are drilling along 1 wall or 2 walls?

You need to get some degree or air circulation, and might not need many holes actually. Gas type baffle vents can prevent howling gales if the prevailing wind blows at one wall, buffetting the air into the room as it were.

[John Rumm]

So? the hole will be about half a brick wide, and one and a bit bricks high. Nothing to write home about, and its hardly going to need a lintle over it! A traditional square boiler flue might take out 4 whole bricks.

[asalcedo]

Indeed, I need to get some degree of air circulation with the purpose of lowering the humidity in the basement.

I'll drill holes in all three walls partly or totally above ground level (the fourth wall is underground).

I will also put ceramic vents on the outside. These vents decorate and are similar to other vents in place already.

I've been told that to give proper ventilation the sum of the open surfaces of the vents should be 0.1% of the surface of the basement, which actually amounts to quite a few holes...

That coincides roughgly with

"Many building codes require that foundations be cross-ventilated. The amount of ventilation that is recommended or required to meet regulations is roughly one vent per 150 square feet house area. "

from

[PeterC]

If a hole has to cross one or more mortar lines, is there a device that will detect ties? For some things, such as an extractor fan, there's oftten a choice of position so avoiding a tie makes sense.

[John Rumm]

in. Made worse by having solid walls that encourage condensation. This slowly tends to run down the walls and soak them from the bottom up. Lack of airflow in the underfloor space seemed to be the biggest problem. Stuck in 9 extra airbricks (using a brick removing chisel on the sds), and that seems to have improved matters greatly.