Wing Tipped Countersunk Tek Screws

[Shultzy]

I'm due to fit bi-fold doors which require the head to be fixed to a steel beam which is 6mm thick. The included screws are "Wing Tipped Countersunk Tek Screws" (see below). I've never used these before so I thought I'd ask for any tips. Do they need a pilot hole, what are the wings for, do I need a powerful drill.

https://www.tcfixings.co.uk/main/produc ... k-Screws/1

 

[RobinBHM]

The wings drill the shank hole through the timber part, they get knocked when they hit the steel.

They work well, but sometimes it helps to pre drill.

 

[NickN]

1) A small pilot hole can be useful to prevent wandering initially and guard against timber splitting.
2) The wings basically make sure the hole in the outer timber becomes the same diameter as the thread behind the wings, which results in the same effect as pre-drilling an exact size hole - the outer material will get pulled tight on to the metal inner material. This happens because when the wings reach the metal surface they will snap off, allowing only the thread to tap the metal for a secure fix.
3) A normal drill should be fine, but ideally run at a slower speed.

 

[Shultzy]

Thanks Nick, I'm surprised about the slower speed as I've had suggestions that it should run at a faster speed when drilling the steel then slow when the thread grips.

 

[NickN]

Well, most hand-held electric drills are probably going to be in the right range anyway - no more than around 2,000 rpm ideally, less in stainless steel.

 

[Shultzy]

Thanks Nick. On another point the kit contains 7.5mm x 100mm concrete screws which have to be put in to the brickwork. Would 6.5mm holes be a suitable size to pre-drill into the brickwork?

 

[NickN]

6.5mm holes would be perfect for that ccasion5:

(Funny really, I'm no expert on these types of things actually, but have recently had to do both the jobs you asked about with the same fixings!)

 

[Shultzy]

Excellent. Although I've been diy-ing and woodworking as a hobby for 50years its my first time with these type of industrial fixings. I'm used to using plastic wall plugs and the thought of screwing straight into brickwork didn't seem quite right. Thanks for the info.