Spade drill bits are normally used only when you only need a hole that’s “good enough” and you care more about how much time and effort it takes to drill the hole. For example, holes through studs for electrical wiring will be hidden in the wall when you are done, but you need to drill a lot of them. That’s when a spade drill bit is useful.
I recently purchased a set of Bosch Daredevil Spade Bits at a big box store because they were a good deal (set of 6 for $10) and my existing bits were dull and not hex shank. I thought the threaded conical tip, like a wood boring bit, was an interesting feature.
I was amazed at how much better these worked than other spade bits I have used. The threaded tip serves several purposes:
- Keeps the bit centered when starting.
- Literally pulls the bit through the material. I did not have to push the drill at all until it got to the point the tip came through the other side (and if you were drilling something backed with scrap wood you wouldn’t need to, or you could switch to drilling from the other side).
- Prevents vibration/chatter and the bit bouncing around the hole.
The resulting holes were where I wanted them, were more round than holes from other spade bits, had fewer blow out” splinters, and were easier to drill.
I also looked at Irwin Speedbor MAX (which have three cutting blades) as they also have threaded tips, and probably work as well or better due to the extra cutting edge. But I like that the Bosch bits lay flat (taking up less room in a tool box) and were cheaper.