Impact drilling many holes in brick

Hi Folks,

I'm doing some renos and as part of the process I am having a patch panel put in a cupboard with data and coax cabling to most rooms of the house - lots of nice new data toys. The cabler only has a small time window available when I need the job done but is quite happy for me to do some of the up front grunt work to limit what he has to do on the day.

The house is double brick and I'm going to drill the bricks at the required locations so that I can use flush mount plates rather than those tacky boxes.

I looked at the cost of diamond core bits which were a bit steep for my blood (especially as the only ones I could find South of Adelaide today were in sets of multiple bits most of them much bigger than I will ever need). I'm not sure if my drill would push them anyway!

The cabler suggested that I drill multiple holes in a rectangle pattern with an impact drill and then break the middle out with a cold chisel.

First, is he right? Is it achieveable that way in my lifetime? Or is he indulging himself in a little tradesman's whimsy at my expense?

If so, what size and type of masonry bit should should I use? Many smallish holes, or a smaller number of bigger ones? How far apart should the holes be for an "easy" break out of the centre? I have seven locations to do in the next week, so I guess at least 100 - 200 holes all up... How many bits will I go through?

I have an ancient Ryobi HPD-18VR impact drill (about 550W) which has given me good service for many years - will this do? I have used it for the occasional hole for a dynabolt in the past and it has coped just fine, but hundreds of holes will be more of a challenge.

If I drill the holes close enough will the centre come free in a single piece? And in that case can I attach a bolt and some string so I can fish out the lump?

I guess the bottom line is I want to do this job right and am willing to get whatever tools and consumables I need to achieve that - but I don't want it to turn into a case of "The Gas Man Commeth" (does anyone else remember Flanders and Swann?). Do I just grit my teeth and get the core bits and tell myself it's an investment in quality tools for the future?

I'm sure some of you have been down this road and have solved it in wierd and creative ways - c'mon: fess up!

Cheers, Dieter.

So you want to install the metal insert box?(mounts in flush)
Dont bother with the core bit... they not real good at square holes!

Honestly the neatest way is to use the messiest way, use a 4" grinder with a diamond masonry blade and plunge cut the rectangle shape, then using your drill with a depth stop(set to 50mm) drill multiple holes to remove the render/brick.
Then clean up with the chisel.

Its best not to belt the hell out of the wall as you can weaken the wall by killing the mortar, so drill away as much as possible so you use the least amount of hammering.

Do you have a air compressor? If so you can buy a chipper gun(mini jackhammer) pretty cheap to do the grunt work, the bonus is they dont damage the structure of the wall like a hammer and chisel does.


Hint, while drilling/cutting/chiseling have a vacuum cleaner going close as possible to the work. I actually duct tape the hose to the grinder it stops about 95% of the dust, if the area(being cut)can be wet down this is best as it stops all dust, use a squeezy spray bottle... often!

That sounds like the advice of someone who has been there and done it - thanks!

Off to the tool shop to investigate with those thoughts in mind!

I'll let you know how it goes.

Cheers, Dieter.

Well, lucked out at Flintware - they had very nice 105mm diamond wheel for $27.00 which seemed good value for money. Turns out it had been ticketed incorrectly and should have been about twice that much! As I left the store they had somene rapidly retrieving the rest for correction!

Thought you might be interested in the following which I found this afternoon:

http://www.armeg.co.uk/electrical-box-sinker-tools.asp

The videos at the bottom of the page are pretty amazing! Haven't been able to find anything like this on sale in Oz...

I will try the diamond saw / masonry bit holes / air hammer approach you suggested in the next few days.

Cheers, Dieter.

I wouldn't use a normal hammer drill for that much work - you stand a good chance of killing the poor thing, and if it is otherwise a good drill that would be a shame.

A rotary hammer is the tool for masonry. Bunnings have an Ozito for $69 which comes with a couple of chisel bits. I haven't actually used one of these but it's probably just the ticket for a job like yours. You'll probably need an SDS drill bit for the actual holes (but they are generally tougher than your standard masonry bit anyway so 1 should do) then you can pop in a chisel bit, turn off the 'rotary' and just use the 'hammer' to knock out the bits in between.

Thanks Harry72 and WortGames,

I took the various bits of advice and all went well - on closer examination I noticed that the existing power points on this exposed brick wall (the ones in the other rooms are under plaster and are a mystery to me as yet) are vertical and use a brick that has been cut short. I took the path of making a clean edge with the diamond wheel in the grinder and then drilling a line of 6mm holes across the other end of the same brick and in the mortar. The Ozito rotary hammer made short work of it - very pleased I got it rather than using the old drill.

It looks like my mortar courses are a little tighter than normal - I got some Clipsal 157/1 wall boxes (which are a little shorter than the 157) and these just barely don't fit. I squeezed them a little in a vice and they still don't quite make it. I may be able to just bash them home for an "interference fit" when the cables have been pulled, but it seems a little agricultural. Any thoughts?

Many thanks again for the advice which was right on the money.

Cheers, Dieter.