Can't drill wont drill?

[kaseryn]

I live in a block of council flats circa early '70s of concrete frame build. Ages ago i tried putting some blinds in one of the windows with my then non-sds hammer drill to no effect and reasoned that i might be hitting a steel lintel or especially dense area of reinforcement above the windows, i.e. a mini-beam/lintel. This was years ago and in the meantime i've gotten an SDS drill and had cause just now to drill the ceiling again. I thought i'd be a doddle this time i not only had the concrete busting new drill but wasnt even working in the window area.. i was trying to change a ceiling rose over for a new light fitting that needs 4 holes drilling... annnyyywaay..
no go.. no joy. punched loads of test holes and nothing goes more than a bit beyong plaster.. what gives? Even giving it welly all i get is a hot and blackened masonry bit. I tried it on the floor and can drill through that ok.. has anyone heard of anything like a steel plate being in such a ceiling? What can explain this impenetrable barrier?

 

[Softus]

It's possible that you keep hitting steel reinforcing rods in pre-cast reinforced concrete members and/or rafts, but, to ask a stupid question, have you made sure that you're using the power drill on the hammer setting?

 

[kaseryn]

Hi yeah i am using the hammer settings.. i'm actually a shuttering chippy by trade so am used to having to drill into src and sometimes dodge bars but this doesn't seem to be the case here.. i mean nothing gets through beyond a really short distance.. doesn't make sense!

 

[Softus]

Cheap SDS drill with a poorly designed percussion profile?

Cheap soft drill bits?

Have you tried any of the ubiquitous carbide hardened drill bits, for example these ?

 

[kaseryn]

Yes, and yes.. but would the cheapness make that much difference? I'm using the cheap bits that came with it. Was looking at a Hitachi before but i seem to remember someone linking a good deal on a Dewalt sds drill before..

 

[kaseryn]

thinking about it, as they started to wear.. the bits showed that brassy colour.. isn't that carbide tipped?

 

[^woody^]

I am not aware of any steel plates being in these floors. There is steel re-inforcement bars but these are typically 50mm up from the ceiling. There may be the lighting conduit, but you would know about that!

A cheap SDS may perform just like a normal hammer drill, and if the bit is soft or blunt then you will go no where.

Try drilling a smaller hole first and then widen it. If not, then try a metal drill and take the hammer off - see if any metal bits come out. If not, then you would need a better SDS.

In any case, you would need to be careful where you drill so close to the electric rose fitting

 

[JohnD]

Some of the system built towers (after Ronan Point collapse) had steel angle bolted between ceilings/floors and wall panels to stop them falling apart.

 

[^woody^]

IIRC, several types of system built high-rise and low-rise flats and houses have angle iron brackets or cleats at wall/ceiling/floor junctions, but these are confined to the very edge of the panels and no where else

 

[kaseryn]

thats what i thought.. even with trick-track i'd be getting what.. 35mm? but as i say loads of holes and none of em got that far... it's near the center of the room so i guess it wont be any angle bracket.. the metal bit sounds a good idea.. i'll try that and a smaller masonry bit and see what happens. If none of those help can anyone give me a link for a good deal on a reasonable sds drill?

 

[seasickstevie]

Had any luck yet?
Hope you haven't drilled through the conduit feeding the light!

Assuming it's not too late. If your using a steel bit (untipped) to drill the reinforcement bars, drill in a position diagonal to the light position. In other words slightly towards a corner of the room.

This will reduce the chances of hitting the conduit as they should run perpendicular to the walls.