Step bits are great for sheet metal, but also plastics. They don't grab and destroy the plastic. Just another FYI good use for them. And rather than go out and buy plastic drill bit, use a step drill.. also great for brass.
Can you use RotaBroaches to cut holes in thick aluminum, say 1/2" thk.? Do the RB cut over or under? I see on the Hougen website that they have a step drill and Industrial annular cutters for deep holes. I'll email Hougen tech support. I'm interested in a replacing a few of my Lenox hole saws.
I have had a cheap one that I bought 10 or 15 years ago, I didn't use it that often until last week when I needed to drill different size holes on a small sheet of( 20Ga) Mild steel,the step drill worked really well.
I'd like to to buy a decent size one like 1/4" to 1.1/4" for the shop for those rare occasions when nothing else works as fast or as cleanly as a well made ,good quality step drill.
Now Viking seems to be well made but (@ $140(set of 3) it is way too expensive for my hobby /occasional use.
what manufacturer comes to your mind when you shop for step drills?
Sorry I don't have a picture that I can post, I'll try to describe it, basically you grind the drill so that it has a central spigot that will guide the drill as it cuts, and you grind the normal cutting edge down at a slight angle to be lower near the central guide and the outer corners contact the metal first the drill will resemble a traditional wood bit, but the central guide will not have the thread section on it. Sounds a bit odd. google grinding a drill bit to cut sheet metal. there a quite a few videos on you tube etc.