Which drill bit for a lintel?

If it is a roller blind turn the bracket to the right direction and fit inside the window recess with the brackets being screwed on to the side wall.

If you have steel lintels it can quite a problem getting a drill to go through them.

You may however have hit a stone in the concrete.

If you have a concrete lintel get tungsten carbide tipped drills to start with just a very small one, I use one about 2mm, to check how far it will go before drilling out with the correct size for the job. Remember to use the hammer setting on the drill.

The difference between a tungsten carbide tipped (masonry) drill and a normal HSS drill is the tip. TC tipped have tips that are wider than the stem.

I would add if it is steel do not try to drill out to the correct size in one go start at about 2mm and work up in 2mm increments to widen the hole each time.

Alternative 3 is to use no nails grip adhesive.