The only one that is not obvious is the swage form but if you look closely you see it is triangular at the tapered tip and it just squeezes the threads in there with brute force. Those screws are as hard a chinese algebra and will strip a socket before they break. We were using them in 1/8" mild steel square tube. The pointed sheet metal screw just gnaws a hole in sheet metal and cuts threads. The other two machine have some sort of "tap", either 4 flutes or one big one. The self drilling actually has a drill bit style tip. (generically called Tek screws) They are best in fairly thin stock (up to 1/16" steel or 1/8" aluminum). You may be able to brute force them into thicker stock if you have a big enough driver.