What Is a 1 1/2 Drill Bit Used For? | Holes That Fit Pipe

A 1½-inch drill bit cuts a hole about 1.500 inches (38.1 mm) across, and its job depends on the material: wood-boring bits run pipe and cable through framing, carbide and diamond bits cut masonry, tile, and concrete.

A 1½-inch self-feed bit and a 1½-inch diamond core bit cut the same diameter, yet one is useless in quartz and the other in a stud. Pick by workpiece first, shank second; pick by diameter alone and you’ll stall a drill or burn a bit.

What Does a 1 1/2 Drill Bit Cut Through?

A 1½-inch bit covers four material families — wood, metal, masonry, and tile or stone — and the cutting geometry changes with each. The diameter is all they share.

• Wood framing and carpentry: self-feed, auger, spade, and hole-saw versions cut rough or finished 1½-inch passages for plumbing, cable, and conduit through studs and sheets. McMaster’s catalog groups these as rough-hole tools for wire and pipe.
• Metal: high-speed-steel twist bits handle general drilling. One listed 1½-inch HSS model carries a ½-inch reduced shank, a 118° point, 6-inch overall length, 3-inch flute length, and a 3-inch maximum drilling depth — rated for low- and medium-tensile-strength materials.
• Brick, concrete, and block: carbide masonry bits and hollow core bits remove a core rather than a solid plug, ideal for running pipe and conduit through a wall.
• Tile, glass, stone, and countertops: diamond hole saws and core bits cut clean openings for drain lines, pipes, and sink installs. A listed 1½-inch diamond bit is specified for glass, ceramic, porcelain, granite, quartz, and tile, and calls for water cooling.

What Bit Type Do You Need?

Match the bit to the material and the drill’s chuck — get either wrong and the bit won’t spin or won’t survive.

Two shank traps catch people. A reduced-shank bit’s shank is smaller than its cutting tip so it fits a standard chuck — that’s why a 1½-inch bit can run in a handheld drill. A ¾-inch Weldon annular cutter needs a compatible magnetic drill or an arbor for drill-press use, and that arbor isn’t included. Milwaukee’s 1½-inch core bit uses a 5/8-11 thread and needs an adapter for tools running a 1¼-7 thread. Check the connection before buying — our tested 1 1 2 drill bit roundup lists which shanks fit which drills.

How Do You Drill a Clean 1 1/2-Inch Hole?

Secure the workpiece, mark the center, and let the bit cut at the manufacturer’s speed and feed — forcing a large bit is how holes go oval and drills go sideways.

1. Identify the workpiece and pick the matching bit type.
2. Confirm the hole diameter and depth. “1½ inch” is the cutting diameter, not the shank size or drilling depth.
3. Confirm machine compatibility — standard chuck, magnetic drill, or threaded spindle.
4. Clamp the workpiece, mark the center, and keep the drill aligned.
5. Run the recommended speed, feed pressure, and coolant. Diamond tooling for hard tile and stone gets water cooling where specified.
6. Withdraw periodically on deep solid material to clear chips. Don’t force a bit that stalls or overheats.
7. Clear burrs and debris before installing pipe, cable, or hardware.

The hole is done when the bit exits clean on the far side and the opening passes your pipe or cable without play.

What Goes Wrong With Large Bits?

Torque and material mismatch cause nearly every failure at this size. Self-feed bits catch suddenly and can bind hard, so use auxiliary support where the drill accepts it, keep a firm grip, and keep loose clothing and hair clear of the rotating bit. Eye protection is not optional.

Then the material rules: a wood bit won’t cut concrete, and a standard HSS bit won’t cut masonry. HSS, high-carbon-steel, masonry, carbide, and hole-saw tooling are distinct categories, and the cutting geometry decides what each survives.