Fixing down threshold

[hairgoneJohn]

Hi

I've got a steel security door with an aluminium threshold on a concrete floor. The threshold has bent up about 3-4mm at the middle and is stopping the door closing. Tapping the threshold down with hammer doesn't work as it springs back. I need a small fixing that will be flush with the thinnish threshold so a small countersunk screw would work but I can't remove the threshold to put in a rawlplug.
I have looked at masonry screws but they seem to start at about 5mm which is too big. I don't need a large holding force.

Any ideas please?

 

[footprints]

Drill and countersink plate sort out a suitable length stainless or other rustproof screw, drill a hole in the cement with masonry drill, hoover out. Use a small plastic plug/strip of old fibre rawlplug or matchsticks and screw into it.

 

[hairgoneJohn]

Excellent. Thanks