Cutting ToolsConsumable
Hole Saw
A toothed cylinder on a central pilot bit, cutting a large circular hole with an ordinary drill. For openings where a drill bit alone would be the wrong shape and a jigsaw the wrong size.
What it does
- Cutting openings for pipe, conduit and fittings
- Holes for locks, sockets and recessed hardware
- Large clearance holes in sheet and board
Materialswhat it is used on
All materialsWhat to look forthe judgement calls, before the spec sheet
- Size the saw to the outside diameter of whatever passes through the hole. For a pipe with a wall thickness, that is the outside diameter, not the nominal bore — DN25 pipe is 33.7 mm outside, and a 25 mm saw will not pass it.
- Tooth pitch follows the material: fine for metal and sheet, coarse for timber, a different body again for masonry. The same saw in the wrong material either clogs or burns.
- The pilot bit sets the location and the saw follows it. A slender pilot in a hard material wanders, so centre-punch first.
Misuse and safetythe ways this tool causes rework
- It cuts a ring and ejects a plug. On a through-cut into a void the plug drops; on a shallow cut it jams the saw. Know which side the plug is going.
- An ordinary drill is not built for the torque a large hole saw needs. Use a low speed and expect the clutch, if there is one, to be the thing that saves your wrist.
Frequently asked questions
What size hole saw for 25 mm pipe?
The outside diameter of the pipe, which for a nominal 25 mm bore is 33.7 mm — nominal bore and outside diameter are different numbers, and the fitting passes through the outside one.
Why does the hole saw jam?
Usually the plug. In thick material the cut plug binds on the saw body, and in sheet the saw breaks through and grabs. Reduce speed, clear the chips, and start and finish from opposite sides where the material allows.