Help!
I bought a couple of garage door frames from Bunnings some time ago. I had erected them and clad them with 7mm marine ply. Unfortunately, it wasn't effective and after a while it started to buckle and eventually became so bad I had to pull it off and replace it.
The door frames are steel, I believe and made of about 20mm square tubing.
I received advice that wooden slats was the best option and I obtained 19 x 100 pine slats and after a sand to smooth, undercoated and top coated them with exterior paint.
I was advised to use galvanised 8g -18 x 32mm wing screws for fixing and to put 2 of each into top, middle and bottom rails and that the were self tapping and I shouldn't need to drill pilot holes, that they would just screw right in and I wouldn't need to drill pilot holes first.
Today I went to start the job.
* I clamped the first slat to a frame
* Tried using a cordless drill and bit to drive the first screw - it went through the wood but made no impression on the metal.
* I tried using a corded power drill but again without success.
* I then drilled a pilot hole slightly smaller than the screw diameter.
* I tried driving a new screw by using the pilot hole but again it was unsuccessful.
Obviously, I am doing something wrong or have the wrong screws or ?
Both of my drills are in good order and working fine on other jobs, they are not old and worn.
I used a new, for metal, 4mm bit for the pilot hole.
So, I'm not sure what is the problem?
Do I need different screws?
A better quality bit of a particular type?
Some form of lubricating oil for the screwing into the metal?


Can anyone advise me what I might need to do, please?