A self-drilling screw does three jobs in one pass: it drills the hole, cuts the thread, and clamps. No pilot hole, no tap, one tool. That only works if the point matches the metal.
Quick answers
What does the #2 in a #2 drill point mean?
It is the size of the drill point, and it has to match the thickness of the base metal. A #2 point is for light gauge metal; tell us the substrate and we will confirm the point before you order.
How long should a self-drilling screw be?
Long enough to pass through everything being joined, including any gap, plus at least three full threads past the back face.
Why use 410 stainless on a facade?
410 stainless can be hardened enough to drill its own hole and still resists corrosion. A zinc-plated carbon screw rusts at the head and streaks the facade, and 18-8 stainless is too soft to hold a drill point.
Can I buy the screws from you right now?
Not off the shelf today — fasteners are off the site while we settle the line. We can still quote them: tell us the substrate, the length and the quantity and we will come back with a price and a date.
The point is sized to the base metal
The number after the hash — #2, #3, #4 — is the drill point, and it describes how thick a metal the screw can get through before its threads engage. A #2 point is for light gauge metal.
Put a point that is too small into thicker steel and the flutes fill before the hole is finished. The screw stops cutting and starts spinning, the friction work-hardens the metal, and then it snaps — usually flush, in a place you now have to drill out.
Too large a point in thin metal is the opposite problem: the drill section passes clean through before the threads reach the material, so nothing grips.
Measure the base metal. If you are not sure, tell us the substrate and we will confirm the point before you order.
Length
Count everything the screw passes through: the trim or clip, the gap if there is one, and the base metal — then add enough for at least three full threads past the back face. Three threads is the working minimum for holding power.
The common mistake is forgetting the gap. A trim standing 1/16" proud of the frame eats 1/16" of your engagement.
Why 410 stainless on a facade
410 is a hardenable stainless. It can be heat treated hard enough to drill its own hole and still resist corrosion — which ordinary 18-8 stainless cannot do, because it is too soft to hold a drill point.
The reason it matters on a building: a plain carbon screw with a zinc coat will eventually rust at the head, and the rust runs. You get a brown streak down an aluminium or glass facade from every fastener, and no amount of cleaning fixes the source. On an interior partition nobody cares. On a street elevation it is a callback.
Flat head, and where it belongs
A countersunk flat head pulls down flush into a matching countersink — which is what you want under a trim, a cover or a snap-on bead, where anything proud would stop the cover seating. Where there is no countersink, a hex washer head spreads the clamp load better.
What this would be
#8 x 3/4", 410 stainless, flat Phillips head, #2 point — sized for light gauge storefront and curtain wall framing, by the box of 1,000.
Fasteners are not listed on the site at the moment. Ask us with the substrate and the quantity and we will price it.