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• This is a plug cutter for bones.

• This is a bit for drilling square holes in wood. It’s just an ordinary round bit with a square chisel around it. Drilling a square hole in metal is also possible, but requires a more complicated tool that is beyond the scope of this website (that’s code for I don’t know how they work).

• Tenon cutters make a smooth cylinder, like a plug cutter, but they also cut a smooth, flat bottom around it. The tenon can then be inserted into a matching mortise, for example in chair construction.

• Plug Cutters

• This drill is quite specifically for pineapples. The handle comes off so you can pull it out the other end after you’ve drilled all the way through, slicing and coring at the same time.

• Hole saws for metal look like a hacksaw blade wrapped in a circle. If you have one hole saw, you probably need a bunch. They come in sets with many diameters, but only one or two mandrels and pilot drills.

• This hollow chisel mortiser creates square holes in wood to receive square tenons.

• This hole saw has a diamond blade for long life cutting hard masonry.

• This looks like a carbide-tipped concrete saw in a circle, so no surprise that it’s for cutting large holes in concrete.

• This used to be a wood-cutting hole saw, which I tried to use to cut through the plaster lathe on my ceiling. It did not go well, as you can see from the fact that the teeth are nearly gone. I had to switch to a tungsten carbide version: the plaster in plaster lath is not like drywall, it’s more like real concrete.

• Hole Saw

• This is another, more exotic, fruit drill. It creates two separate, threaded together spiral loops of whatever fruit you drill it through. Nifty, if you happen to need spiral fruit.

• This hole saw looks like a round wood saw: it’s for cutting large holes in wood.

• Hole Saw

• I used one of these adjustable hole saws once. Hateful things. Get a set of fixes sizes instead.

• Plug cutters work to make a smooth inner cylinder, which you remove and use elsewhere, leaving a hole you don’t care about (usually in a left over piece of wood).

• The plug you get when using a hole saw.

Do you have a better example of this kind of tool? Let me know by leaving a comment, and include a picture of it if you can so everyone can see!