Drilling holes in steel

On the general question of drilling holes in steel, how to ensure the exposed metal won't rust? How to paint so they don't?

 

once done drilling clean with a file and spray paint it super easy

 

I just use the little things of touch up paint with the little brush. I sometimes add 2-3 coats just to make sure I got all the bare metal covered; depending on the size or location of the hole. If it's big holes in something I can hit from both sides, then I might just rattle can it.

 

It depends on what the hole is for. e.g., Thread certs; I coat the cert with silicone. Self taping screws; anti-seize.

 

If the hole is hidden I use Cold Galvanize spray, if exposed I use touch up paint.

 

Could you tap the holes for the application? If so paint and than use blue Loctite