Can't drill (window lintel)

[weltonblue]

I am having an awful problem which is driving me insane.

I have just moved into a new house and am trying to fit a roller blind in an upstairs room. The brackets for the blind mean that they have to be fitted to the roof of the window recess. My problem is though that the drill bits only get a little way in before hitting something solid. The drill I am using is quite a powerful corded drill. I am not sure whether it is concrete or steel - although when the drill touches it, it sounds more like steel. I have bought HSS drill bits of a good quality but I just can't get any further. It is really getting annoying now and I don't know what to do other than having to pay someone to fit them for me - I think that would cost a lot of money though

If you can help, please do. The brackets can't be fitted any other way and I can't afford to go and buy a very expensive drill. I have bought an angled drill adapter so that I can drill in the right place (tight in the corner of the window recess).

Thanks!

 

[joe-90]

It will probably be a Catnic. Put a little screwdriver up the hole and if it feels smooth it is steel - rough and it is concrete. It sounds like your bits are not as good as you hope. Nothing to do with the drill - just the bits.

 

[weltonblue]

I wonder now if it might be concrete. I just can't be sure. Do you think I'd be best just to give in and pay someone to do it for me? Would joiner do such a thing? I'm worried I'll end up damaging the wall.

 

[ColJack]

it's steel and you've case hardened it my heating it with the friction from the first bit..
you'll have trouble drilling it now..

you might try a cobolt bit with a small diameter ( say 3mm ) first then one of the right diameter..

 

[pompeyal]

Yep, steel lintel, use a HSS twist drill and self tapping screws, you will have to drill quite close to the size of the screw due to the thicknes of the lintel or if you have them, drill and tap the lintel and use the correct size fixings to secure, probably 20mm long should do it. I have had the same problems in the past when fitting windows.

 

[TicklyT]

If it is steel, don't run your drill too fast, or attempt to use any hammer / impact action - it will overheat and blunt the bit, and harden the steel you are trying to drill.

For a 6mm hole, don't let the drill exceed 1000 RPM. 500 to 700 RPM may be even better.

Many hand drills are designed for woodwork, where much higher speeds are permissible.

You may be able to drill a smaller hole in steel (using, say, a 3mm drill, running at up to 2000 RPM), and attach your fittings with no. 6 self-tapping screws directly into the metal, but check the sizes carefully first - as little as 0.1mm can make all the difference for this method. Appropriate size drill bits are available, but not often from DIY stores.

Cobalt steel bits are more tolerant of high speeds than HSS bits, but even a well sharpened carbon steel bit should cut a hole easily, providing it is kept sharp and isn't run too fast or allowed to overheat.

Some argue that carbon steel bits can perform as well as either HSS or cobalt steels, because they can be honed to a sharper cutting edge. Any advantage is probably more theoretical than practical, as the maximum cutting speeds for carbon steel are lower, and they need more frequent re-grinding to keep them sharp.

 

[weltonblue]

So I am best to use a slow speed (the drill ii have does 2400rpm or 900)? I have started with a 3mm with the plan to then go up to a 6mm

I'll try with the 900 speed then. Is it best to do short busts so as not to overheat the bit?

 

[joe-90]

If it's a steel lintel it should drill easily.

 

[disinfo]

A bit of rocol works wonders.

 

[Dereklee]

A bit of rocol works wonders.

all right. what a sage advice!

 

[opps]

Hi Weltonblue

When you say it is a new house do you mean a new build or a new home/old house.

If it is an old house with a concrete lintel you will need a sds drill.

When green(er) I recall trying to drill a 7mm hole into a concrete lintel with a 705w metabo hammer drill, the bit started to bend after 10 minutes of not getting anywhere very fast.

Next day i bought an sds drill. Hole took 40 seconds.

Hammer drills are crap and inefficient.