Drilling holes in concrete

Question

I'm not what you'd call a handy guy, and now wife wants me to put up curtains. This task is reduced primarily to getting a bit of metal stuck to the ceiling.

I bought screws and anchors. The anchors are a bit shorter than the screws. The clerk in the store told me that's normal. After some soul searching, I managed to drill the holes as deep as the screws. At first, I was worried that the holes were too big, since I can put the plastic anchors in with my finger.

When I try screwing in the screw, I'm physically unable to turn the screwdriver about halfway in (at this point I'm unable to yank it out of the hole either, so I'm assuming that the plastic bit expands on the inside). I don't have one of those screw-driving thingies, but I attached a screwdriver instead of the drillbit on the drill I used to make the hole, and it just "jumps out" every time I press the trigger.

I'm confused. The only possibilities that I can see are as follows:

• I am not strong enough and the drill is in high gear so it can't be used this way.
• Somehow I managed to mix up the anchors and the screws.

Well, here are the culprits:

Oh, don't worry about the hole in the background. That one hit something shiny, so I abandoned it. Anyway, that's about as far as I can screw it the screw without losing my cool. Oh, it's my ceiling btw.

Answer 1

No, this isn't normal. Your anchors don't fit to your screws. What is happening is that the tip of the screw reached the concrete, and, of course, you can't force a screw into concrete - not even with a drill or a electric screwdriver, and certainly not by hand.

This picture shows how anchor and screw should fit into the hole. The hole definitely needs to be longer than the screw. The screw should be a bit longer than the anchor, but not as long. Maybe the clerk saw that you have picked an wood screw and gave you anchors suited for the second situation. It doesn't hurt to use wood screws with anchors in a concrete wall, you'll just have the cap jutting out a bit. But the length of the screw should be only a bit longer than that of the anchor (the surplus should equal the length of the tip + the length of the attached thing), and your cap will stick out a bit if the thing you are attaching isn't soft enough for the cap to sink in.

The table shows how to determine the correct hole depth. It also tells you what diameter of anchor and drill to choose for a given screw. As for the length of the screw, it is determined by the weight it will have to carry. Vertical screws are more problematic than screws in walls, because gravity is pulling in the direction of the hole, not at 90° to it. Light curtains will be OK with your size screw, but don't put any molton on them.

Answer 2

Answer is simple: the screw is too thick (and/or hole is too shallow), just get a 1/2mm thinner screw and all will go in (quite) well, You don't have to replace the plastic anchors. Also check the hole is at least as deep as the screw (if the screw has to be almost all inside the wall).

My suggestion is also to get a drill 'screw-driver' tip. It'll cost about 5€ in an average hardware store.

I usually use 4,5mm (thick) screws for 6mm anchors (and holes).

Answer 3

for larger holes there are options:

(1) use a small (long) drill and drill MANY holes in a circle and knock out with sledge when done. divide and conquer.

(2) use a bosch diamond hole saw - gets expensive for larger diameter

(3) use a less expensive pneumatic hammer (select cutter bit not hammer bit) or rent an (electric) jack hammer. these are slower than hole saws and difficult for larger diameters.

(4) examine hole saws. they have a castle top (like castle in chess). you can take a large deep socket and slot the top with a die grinder. drills don't have enough power but impact wrenches DO. drawback: limited socket radius and depth