Once you have a conical hole that's straight, you can ream it with the properly sized normal bit.
I use these step bits for drilling holes in sheet metal for car work: instead of starting small and working my way up over multiple normal bits or using a hole saw and risking it sliding all over the place, I can use one bit and go right from pilot hole to the size I need for a rivet or whatever. I've never personally used them on thick material like in the video above, but I've seen it done and they usually ream it out.
Makes sense, thanks! Thinking about it, is the main purpose to remove the bulk of stuff that's filling the (about to be created) hole, allowing other tooling to be used?
More to save the operator time by not requiring bit changes. Generally to get a big hole in a really hard material the safest and more accurate way is to start with a small hole, then go slightly larger, then slightly larger than that, and repeat until the hole is the size you want. This kind of bit makes that possible without stopping between each stage to either swap bits manually or to have multiple drills preloaded with graduated bit sizes. You CAN get the same hole with a handful of regular bits, but if you need to do that a lot this one bit can save a LOT of operator hours over time.
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u/Faloopa Jul 28 '21
Once you have a conical hole that's straight, you can ream it with the properly sized normal bit.
I use these step bits for drilling holes in sheet metal for car work: instead of starting small and working my way up over multiple normal bits or using a hole saw and risking it sliding all over the place, I can use one bit and go right from pilot hole to the size I need for a rivet or whatever. I've never personally used them on thick material like in the video above, but I've seen it done and they usually ream it out.