blindsdrillscrewswindows
I've bought a pair of blinds that came with 1 1/4 inch screws; I'm unable to drill deep enough into the frame to fit the screws, the screws are sticking about 1/8 of a inch out . I end up hitting something pretty solid while drilling. Can I just go to the store and get slightly shorter screws?
The blinds are 69 inches long, and there's 3 brackets each with two screws, it probably weights 6-7 lbs at most.
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.
There is quite an 'overhang' of the screw (24 mm) from the wall. That's why you need at least 6 mm screws in diameter. It's head is about the maximum you have.
That implies 12 mm anchors, which are 60 mm long here.
The resulting screw would be 6x80, or 6x90, if you have longer anchors.
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Using plain screws into just about any material other than wood or metal will not provide a strong support, especially if the weight that the screw is supporting is trying to pull the screw shank straight out (rather than pulling across the shank of the screw).
From your pictures, the surface appears to be plasterboard (or less likely, plaster), which has to be attached to a support structure, either wood, steel or concrete.
Wood To test if it is wood under the plaster/plasterboard, remove a screw and insert an awl until it just stops.
With some force, try to push the awl in further. If it is wood, the awl should sink in a bit, but not too easily. There should be enough wood to allow you to drill into it and seat the screws fully. You probably need at least 1/2 inch of screw thread in wood for a safe hold on blinds. More is better. Remember that the plasterboard/plaster doesn't count. Try to guage how thick it is (probably either 3/8 or 1/2 inch) and add that to the depth into the wood.
Steel If the awl doesn't sink in, it may be a metal stud or a metal beam. If you hit something hard and the point can slide easily side to side, it is probably metal. Try to drill a small hole through it with a sharp drill bit. If it is a steel stud, you will be able to with a bit of pressure. You can then use a sheet metal screw to hold the bracket up. If it is a steel beam, you will not really be able to (it is too thick and hard). You will need a whole different mounting system.
Concrete If the awl stops but can't be slid along a hard metal edge, it may be a concrete support structure. The awl should feel as if it is digging into something a bit gritty. You can mount into concrete but need to use a masonry anchor.
To insert the anchor, you first need to drill a properly sized hole with a special masonry drill bit.
It has a carbide insert in the tip. It is slow going and should be much harder than the plasterboard/plaster. The dust probably will be greyish or tan in color. Be sure not to drill a hole too close to another hole, or the concrete between them may crumble. You then need to insert the anchor and screw the bracket into it.
While it is theoretically possible to get a good enough mount in concrete like this, it is hard. This is especially true when the load is dynamic (moving) the way blinds are.
Plaster/Plasterboard While it is possible to hang light to moderate loads on plasterboard or plaster, it is really only safe when it is a vertical surface, not an overhead one. You can use various anchors, but not when the force is pulling directly out from the surface rather than down along the surface.