A hole saw (also spelled hole saw), also known as a hole cutter, is a saw blade with an annular (ring) kerf that cuts a hole in the workpiece without removing the core material. It is employed in the construction of a drill. A pilot drill bit (arbor) is typically located in the center of a hole saw to prevent the saw teeth from walking. For relatively large holes (especially those larger than 25 millimeters (1.0 inch), the fact that a hole saw creates the hole without requiring the core to be cut up makes it preferable to twist drills or spade drills. The same hole can be dug faster and with less force.
The depth of a hole saw’s cup-like shape limits the depth to which it can cut. Most hole saws have a relatively short diameter-to-depth aspect ratio and are used to cut through relatively thin workpieces. Longer aspect ratios, on the other hand, are available for applications that require them.
Cutting with a hole saw is similar to some machining operations, known in the trade as trepanning, in which a cutter similar to a fly cutter is swung in order to achieve a similar result of annular kerf and intact core.