I have tried to drill holes in my ceiling to put up a projector screen weighing about 9kg. I've managed to drill one hole and have put up the first bracket which seems very steady, but the second hole (about 180cm away) I just haven't been able to manage. I've tried 5 (!) times and each time I've hit something rock hard after about 25mm depth. The hole needs to be 55mm.
After the third time, I got tired and went to buy a stud scanner that should be able to detect metal and wood down to 38mm depth, but even though I've made sure at least 10 times that nothing is under the surface, I still keep hitting something. My first thought was rebar, but it should have been detected by the scanner (which it did at the first two points), and it doesn't look like metal when I try to look into the hole. After much filling and sanding, I'm tired of it and therefore ask for your help.
The house is a classic apartment building in a Stockholm suburb built around 1940. I have a hammer drill and concrete drill bits that have worked for brick and other materials in my apartment, but here it's apparently failing miserably.
I've tried drilling holes in my ceiling to install a projector screen weighing about 9kg. I've successfully drilled one hole and installed the first mount, which seems very steady, but I just can't manage to drill the second hole (about 180cm away). I've attempted with 5 (!) holes and every time I've hit something rock-hard after about 25mm depth. The hole needs to be 55mm.
After the third attempt, I gave up and bought a stud scanner that should be able to detect metal and wood up to 38mm deep, but even though I've ensured 10 times that there's nothing under the surface, I still encounter something. My first thought was rebar, but it should have been detected by the scanner (which it did at the first 2 points) and it doesn't look like metal when I try to look into the hole. After much plastering and sanding, I've had enough and am asking for your help.
The house is a classic apartment building in a Stockholm suburb built around 1940. I have a hammer drill and concrete drill bits that have worked for brick and other materials in my apartment, but here they apparently fail completely.
Grateful for all tips.
If you have an old "traditional" hammer drill, unfortunately, you won't get far with real hard concrete. What you need is a Rotary Hammer. It's essentially the same, but with significantly longer and harder blows. With the same machine, you can also take drill rotation and use it as a demolition hammer. They cost about 500kr at Jula and Biltema. There are probably cheap ones available at more places. With one of these, it's like drilling through butter.
It usually works with a percussion drill as well, but then it also requires fresh drills of good quality.
A percussion drill fixes the hole in about 2 minutes with a worn-out drill, a rotary hammer with SDS drill in 15 seconds, and the drill is practically like new.
In the past, when Ikea was something to have, there was a really good value rotary hammer to buy there intended for just what you were planning to do (I have one and a considerably more expensive/stronger/better Makita, and I prefer the weaker but simpler Ikea for such simple jobs).
