Drilling problem

[alchemistkevin]

Hi,

We live in an appartment block built in the 70's (concrete walls) - I'm trying to put up an LCD and trying to drill holes according to the plate I need to mount.

So far so good...

However, when I start drilling, I can drill one hole easily, lets say on the top part, but the lower part will not drill through.

I can only drill around 2cms....

Then if I move the template down or up a bit... I can drill one hole on either end but I can't on the other...

it seems there's something stopping the drill from going through.

I'm not familiar with the building techniques, would there be metal bars placed at equal locations within the wall and if so that means I can never drill the holes at both the ends!!!!


can anyone comment/help please.

 

[dude_diy]

Im guessing your drilling into an outside wall and not one of your internal walls. It may well be you need a more powerful drill and or a better drill bit. There could be a number of things stopping you from drilling a hole easily. Best advice is rather than splash out on an expensive drill you may not use again, try buying a good quality masonary drill bit. If that doesnt help then try yellow pages for local handy man. Better to get a good fixing on your no doubt expensive TV.

 

[Alastairreid]

first of all a decent hammer drill and high speed masonry drill bit.

if the brick is hard use a smaller bit to pilot the hole moving onto the correct size of bit for the plug.

 

[Symptoms]

kevin - concrete walls ... drilling can be difficult for a number of reasons.

Steel reinforcing bars (rebar) set inside the concrete meaning it's OK drilling for a small depth 'till you hit one. A masonry drill bit will attack the concrete but won't touch the steel so you should change to a steel cutting drill (known as a high speed steel {HSS} twist drill or Jobbers) to get through the rebar.

or

Your masonry drill has hit a hard piece of the aggregate material within the concrete, a flint pebble perhaps.

or

Your electric drill isn't up to the task

or a combination of all three.

The only guaranteed way of drilling concrete is to use a SDS drill (a type of more powerful electric drill) and decent masonry drill bits. Try drilling the holes with a small size masonry drill first then enlarge to the correct size. If you hit a rebar then swap to a Jobbers, a flint pebble should be meat & drink to a SDS drill.

 

[alchemistkevin]

Thanks for taking the trouble to reply

I was using a masonry drill; using HSS sorted me out good...

 

[alchemistkevin]

kevin - concrete walls ... drilling can be difficult for a number of reasons.

Steel reinforcing bars (rebar) set inside the concrete meaning it's OK drilling for a small depth 'till you hit one. A masonry drill bit will attack the concrete but won't touch the steel so you should change to a steel cutting drill (known as a high speed steel {HSS} twist drill or Jobbers) to get through the rebar.

or

Your masonry drill has hit a hard piece of the aggregate material within the concrete, a flint pebble perhaps.

or

Your electric drill isn't up to the task

or a combination of all three.

The only guaranteed way of drilling concrete is to use a SDS drill (a type of more powerful electric drill) and decent masonry drill bits. Try drilling the holes with a small size masonry drill first then enlarge to the correct size. If you hit a rebar then swap to a Jobbers, a flint pebble should be meat & drink to a SDS drill.

all the replies were helpful but yours is such fantastically worded very easy to understand for anyone


Thanks once again


Hope I can gain enough knowledge to help out someone on these forums

 

[AndrewSchofield]

Just a general query raised from the above posts - if the OP is hitting a re-bar, is it OK to switch to a HSS drill and simply drill through it? Will this not affect the structural intergity of the reinforcement and therefore potentially cause further problems?

 

[regsmyth]

Fair point, but really the steel in a vertical wall can't be too critical for localised stability. I guess in an earthquake there might be a problem if lots of the wall rebar had been cut through.
However, you wouldn't go drilling through the rebar in the underside of a slab for example, or the edge of a floor slab. You can use detectors to locate the rebar and avoid it (Ferroscan or something like it), though it's not a very precise art (you get a fuzzy picture and have to decipher which of the blurry dark bits are steel)
In the past I've had to get approval from the client engineer when there's a danger of hitting rebar (and then use a water cooled diamond tipped core bit). Mostly they're ok about it, but not always.
I wonder who the OP should have consulted before getting out his B & D?