I am trying to hang a curtain rod and started to drill the holes for the brackets into a brick wall. The curtains are heavy so I'm using 50mm green wall plugs, a 6.5mm masonry bit and size 10 45mm screws. The first hole went in just fine, but when drilling the second hole I seem to have struck something metallic about 15mm into the brick. I am absolutely stumped to know what it is.
The window is L-shaped with the two sections meeting at a square timber post in the corner, and there is an L-shaped steel lintel visible from outside that is supporting the brickwork above the windows. The curtain rod is comprised of two straight sections and one curved piece that joins them at 90 degrees. The bracket I am starting with is one in the corner, where the straight section meets the curved section, and the hole is about 150mm in from the corner, about 150mm above the window, and about 150mm below the cornice. There is about 10mm of plaster render over the bricks, so the hole I have drilled is too shallow to be of use.
I am thinking of buying a stud finder that claims to detect metal up to 3 inches beneath solid material, so I can perhaps look at the size and extent of this obstruction. Can anyone help suggest what I should try next? I am very new to DIY (in fact this is my first time with a drill) and female (so can't muster too much muscle), but I thought I knew enough about how houses are put together to assume there couldn't be anything metallic inside a solid brick in a cavity wall, above a window to boot. If I have to fill the holes and start again in a different spot, what is the strongest thing I can use so the bricks stay intact? And how close to the original holes can I go without causing more problems?
Thanks for any help.