Screws for steel

[randers]

Hi. I want to fix a key storage box to a steel support holding up a carport roof.
I assume the best way is to use self-tappers. Is it just any or are there special ones for steel (can't be big screwheads as they'll need to fit inside the little MasterKey-type thing).
And is the best way to drill into the steel a kind of pilot hole narrower than the screws then drive the self-tappers in?
Any answers gratefully received, as is any additional advice people might have!

 

[SammyInnit]

Self drilling screws are ideal. Hex head which are used for corrugated sheeting or envelope cladding are idea but they're often hex head with a rubber skirted washer which may hinder the installation of such a thing. Otherwise you can get self drilling gyproc like screws which would do the job. With self drilling you don't need to pilot but if you end up using a self tapping screw it will be easier to pilot first, definitely.

 

[JohnD]

I'd go for nuts and bolts. Use Coach Bolts with the head on the outside, they have no hex or slot to unscrew.

Self tappers, you could hit the points with a hammer to punch them out, if you were a burglar.

 

[SammyInnit]

I'd go for nuts and bolts. Use Coach Bolts with the head on the outside, they have no hex or slot to unscrew.

Self tappers, you could hit the points with a hammer to punch them out, if you were a burglar.

Well seasoned thieves don't really need keys.

 

[JohnD]

round my way we mostly get teen crack heads.

 

[Burnerman]

If your roof supports are thicker than say 3mm, you'll be going some to get self tappers in - although you will succeed if you get the pilot hole just right.
John

 

[Alec_t]

Drill and thread-tap should do it.

 

[Aquaheat]

Google Tek screws. Decent ones will go through 6mm steel with an impact driver with no pilot needed.

Jon