Drilling *very* hard concrete

[chimpanx]

Hi there -

I live in a ground floor maisonette built in the 1960s. Above our upper floor is the lower floor of another maisonette.

There is a thick (8 inches or so) concrete plinth that forms the ceiling of our upper floor and the floor of the maisonette above.

I need to install a curtain rail in one of our bedrooms, but have to use a ceiling / top fix due to the nature of the windows we have. This means I need to drill into the concrete to fix the rail.

Unfortunately, I can not seem to drill into the concrete! I have a 500W corded power drill and need to drill a 6mm hole about 25mm deep into the ceiling. The plaster drills easily enough, but when the masonry drill bit hits the concrete I hardly get any progress into the material. When I've really tried to push hard, the bit has ended up slipping in the chuck.

Please can someone advise what I can do in this case? Ideally I want to drill the concrete - is it just that I have cheap masonry drill bits (which I do - I've tried the 3mm bit with no luck either)? If I can't drill the concrete, can anyone suggest an alternative approach?

Many thanks for your help,

John.

 

[JohnD]

1) is it a hammer drill? And a masonry bit with a brazed-in tungsten carbide tip? (you should be able to see a squareish piece of metal of a different colour slotted into the white metal twist drill).

2) if you poke something up the hole, does it feel as if you might have hit steel rather than concrete?

3) as you say the drill is rotating in the chuck, have you tightened it firmly with a chuck key that fits correctly? This should not happen drilling masonry unless you have penetrated it.

 

[chimpanx]

1. it is a hammer drill - but its only a cheapy 500W Black & Decker corded. the drill bit looks like one piece of metal to me - no clever tip on it.

2. the hole is literally only slightly deeper than the layer of plaster (~10mm) - i can see into it and can't see anything that looks like steel - all i can see is concrete

3. drill bit is tightened into chuck, but its only a cheapy drill so its a hand tighten job. Even when the drill bit is spinning correctly i'm really not getting into the concrete at all - a bit of dust comes out but that's it.

Thanks for your help!

 

[JohnD]

Stert by buying a better quality masonry bit. You can buy Bosch or B&D anywhere. Look at the tip and mnake sure it is packaged as a TCT masonry drill.

For red plugs buy a 6mm drill. If it wanders and makes a loose hole use a brown plug.

 

[chimpanx]

Thanks very much.

I'll get to one of the DIY stores this weekend and pick up a set of better drill bits.

Realistically do you think I also need to get a better drill?

 

[RF Lighting]

If you have a fair bit of drilling to do into hard substrates then I would definatly recommend the purchase of an SDS drill. The DIY range of these drills is pretty cheap these days. (please note, they use special drill bits)

This one is only £30 (but you get what you pay for

I would recommend This one It is good quality and not too dear for the DIYer

 

[chimpanx]

Thanks for the advice.

 

[kaseryn]

Just thought i'd add to this.. chimpanx, a few years ago i had exactly the same problem as yourself. I live in a concrete frame based block and as the window recesses go right to the ceiling line you need to hang from the ceiling.. they already had a baton fixed there to which rails or blinds could be hung but that wasnt right in the recess and as i was fitting a blind i needed a straight fix.. anyway: long story short.. like yourself, no joy.. with a good bit and drill. I came to the conclusion the window area's had steel reinforcement over them, or a lintel with steel in it. Absolutely no penetration, in the end i used the existing baton but built a box around it to hide the fitting/edge light..

 

[milkman]

I've just finished my first job and came up against a similar problem. Two melted bits later I did some research, found this, looked at some of the posts on this forum and bought a 3kg AEG SDS drill. Words like hot knife and butter are what come to mind. Its brilliant.
3kg is about as much as I can comfortably handle and it did what I needed. I've tested it on some concrete fence post and it did fine there as well.

Drill is fine, only gripes are that the free chuck conversion is an old style key chuck and the carry case is very flimsy looking.

Also not sure whether I shouldn't have got the 110v version. I'm intending to do more jobs with this so hopefully it will pay for itself, If this is a one off you can hire them easily enough or get a cheapo own-branded version for about £40.
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Moderator, edited the link correctly

 

[seaangler]

Drill is fine, only gripes are that the free chuck conversion is an old style key chuck

[/b]

you can buy a keyless chuck for it at no great expense - but BEWARE the chuck is not for use with hammer action . Put the hammer on and you'll smash the chuck to pieces