Hole Saw vs Forstner Bit vs Spade Bit: Which to Use for Wood, Metal, and Plastic

A hole saw cuts large through-holes in wood, metal, or plastic; a Forstner bit makes clean, flat-bottomed holes in wood, and a spade bit drills fast, rough holes in wood only.

One wrong bit turns a five-minute job into a burned edge, a cracked panel, or a bit stuck mid-hole. Picking the right cutter comes down to three questions: what material you’re drilling, how big the hole is, and whether the bottom needs to be flat or the hole goes all the way through. Answer those and the choice usually makes itself.

Below is what each bit is built for, where it fails, and the setup habits that keep the cut clean.

What Each Bit Does Best

Each cutter has one job it was designed for, and using it outside that job is where most problems start.

Hole saw: Best for large-diameter through-holes. A hole saw is a cup with teeth that cuts a circular ring, leaving a solid core behind, and it generally needs an arbor and a pilot drill to guide it. For wood, use a wood-rated hole saw. For metal or plastic, use a bi-metal or carbide-grit model the manufacturer rates for that material. Milwaukee’s Hole Dozer bi-metal design uses a 3.5 TPI tooth pattern intended to extend life in metal.

Forstner bit: Best for accurate, clean, flat-bottomed holes in wood, MDF, and composite materials. Forstner bits also handle overlapping holes, edge holes, pocket holes, and cabinet-hinge bores. Milwaukee’s 3/8-inch Forstner Bit (model 48-14-0376) uses precision-ground kerf cutters and a round shank intended to reduce runout. Bosch’s Forstner line is built for splinter-free, flat-bottomed holes, including in end grain and through knots.

Spade bit: Typically the fastest and least expensive route to rough, ordinary through-holes in wood and wood-based sheet goods. A spade bit cuts fast and leaves a rougher edge, so it suits framing and hidden work better than finished surfaces.

Matching The Bit To Your Material

Material decides more than size does. A bit that cuts wood beautifully can ruin a metal sheet or melt a plastic panel.

One rule holds across every material: check the manufacturer’s rating before you spin the bit. A wood-only Forstner bit on steel dulls instantly and can grab the work.

If you’re cutting large holes and want to compare specific models before buying, this roundup of tested hole saws for common materials covers the trade-offs.

Getting A Clean Hole Every Time

Setup and technique account for most of the difference between a clean hole and a splintered one.

1. Confirm the material, hole diameter, hole depth, and whether the hole must be flat-bottomed or through.
2. Verify the manufacturer’s material rating, shank size, arbor compatibility, and drill capacity.
3. Mark the center and clamp the workpiece; use sacrificial backing for a through-hole.
4. Start the drill square to the surface at the manufacturer’s recommended speed.
5. Clear chips periodically with a hole saw; withdraw a Forstner or spade bit to clear chips in deep holes.
6. Ease pressure near breakthrough to limit splintering.
7. Stop if the bit binds, overheats, melts plastic, or shows tooth damage.

When the cut finishes, the hole should have clean, square walls with no burnt edges or torn grain on the exit side.

Common Mistakes Worth Avoiding

Most ruined cuts trace back to a handful of avoidable errors.

• Running a wood-only bit on metal, or assuming a general-purpose bit is safe for every plastic.
• Ignoring arbor, shank, chuck, and drill-capacity compatibility.
• Drilling unsupported wood and blowing out the backside.
• Pushing too hard, which causes binding, overheating, melting, or loss of control.
• Working without eye protection or a secured workpiece.

Milwaukee’s catalog documents its 4-piece Forstner set (model 48-14-0004) at 1/4-inch, 1/2-inch, 5/8-inch, and 3/4-inch — a useful size spread for cabinet and furniture work. Bosch notes its Forstner bits fit portable drills or stationary machines and work with tools from most brands.