Can You Cut Metal with a Rotary Tool? Complete Guide

The short answer is yes, you can cut metal with a rotary tool—but only certain types and thicknesses. Trying to cut the wrong material with the wrong bit at the wrong speed is one of the most common mistakes beginners make.

This guide covers everything you need to know to cut metal successfully with your rotary tool, from choosing the right bit to finishing techniques.

What Metals Can a Rotary Tool Cut?

Rotary tools excel at cutting softer metals and thin gauges. Here's a breakdown:

Easily Cut with a Rotary Tool

• Aluminum: Very soft, cuts cleanly with any cutting disc
• Brass: Soft and malleable, ideal for rotary tool cutting
• Copper: Similar to brass, cuts easily
• Thin Sheet Metal: Up to approximately 18 gauge (1.2mm)
• Tin / Thin Aluminum Cans: Very easy to cut
• Silver / Gold (jewelry): Perfect for precision jewelry work

Harder to Cut (Use Caution)

• Mild Steel: Up to about 1/8" thick, requires cutting wheel
• Stainless Steel: Difficult, wears bits quickly, thin sheets only
• Cast Iron: Very difficult with rotary tool—use angle grinder instead

DO NOT Attempt with a rotary tool.

• Steel rods over 1/4" diameter
• Pipe fittings
• Hardened steel
• Structural steel
• Any material over 1/8" thick consistently

The Right Bits for Metal Cutting

Using the correct bit is the single most important factor for successful metal cutting. Here are your options:

1. Cut-Off Discs (Best Choice)

Thin, flat discs designed specifically for cutting. Available in:

• Aluminum oxide: General purpose, good for steel and iron
• Silicon carbide: Better for aluminum, brass, and non-ferrous metals
• Diamond cut-off discs: Longest lasting, works on all metals

Tip: Use discs no thicker than 1/16" for clean cuts. Thinner discs cut faster but break more easily.

2. High-Speed Cutters

Small cutting wheels mounted on a shank. Great for making small cuts, notches, and shaped openings. Less aggressive than cut-off discs.

3. Carbide Burrs (Shaping, Not Cutting)

While not for straight cutting, carbide burrs are excellent for:

• Removing metal in controlled areas
• Shaping castings
• Smoothing cut edges
• Removing weld seams

Speed Settings for Metal Cutting

Speed is critical when cutting metal. Too fast and you'll overheat the material; too slow and the bit will snag and potentially shatter.

Metal Type	Recommended Speed (RPM)	Disc Type
Aluminum	20,000 - 30,000	Silicon carbide
Brass	15,000 - 25,000	Aluminum oxide
Copper	20,000 - 30,000	Silicon carbide
Thin Steel (up to ga)	20,000 - 30,000	Aluminum oxide
Mild Steel (1/8")	15,000 - 20,000	Diamond or aluminum oxide
Stainless Steel	10,000 - 15,000	Diamond only

Step-by-Step: Cutting Metal with a Rotary Tool

Step 1: Prepare Your Workspace

• Secure the metal piece with clamps or a vise
• Ensure the metal cannot move during cutting
• Place a wooden backer behind the cut line to prevent the disc from catching
• Clear the area of flammable materials (metal sparks fly!)
• Work in a well-ventilated area

Step 2: Choose and Install the Right Bit

• Select a cut-off disc appropriate for your metal type
• Check the disc for cracks or damage before installing
• Install the disc on the arbor with the provided flanges
• Tighten securely but don't over-tighten
• Verify the disc spins freely without wobble

Step 3: Set the Correct Speed

• Start with a medium speed setting
• Adjust based on the metal you're cutting (see table above)
• Lower speeds for harder/thicker metals
• Higher speeds for softer/thinner materials

Step 4: Make the Cut

• Mark your cutting line clearly with a marker or scribe
• Let the tool reach full speed before contacting the metal
• Hold the tool firmly with both hands
• Apply gentle, steady pressure—let the disc do the work
• Don't force the tool; let it cut at its own pace
• For straight cuts, use a guide or straightedge
• For curved cuts, go slowly and follow your marked line
• Keep the disc perpendicular to the work surface

Step 5: Finish the Cut

• When nearly through, reduce pressure to avoid tearing
• Support the piece as it separates to prevent dropping
• Let the cut piece and disc cool before handling
• Use a file or deburring tool to smooth sharp edges

Safety Precautions

Always wear:

• Safety glasses or face shield—Hot metal fragments and disc pieces can fly
• Work gloves — Protect hands from sharp edges and heat
• Respirator or dust mask—Metal dust is harmful to breathe
• Ear protection — Cutting can be loud

Critical safety rules:

• Never use a cracked, warped, or damaged cut-off disc
• Don't apply excessive side pressure—this can cause the disc to shatter
• Keep hands away from the cut line
• Secure workpieces firmly—no holding metal by hand while cutting
• Work in short bursts to prevent overheating the disc
• Have a fire extinguisher nearby when cutting metal

Troubleshooting Common Issues

The disc keeps breaking

• The disc may be damaged or defective—replace it
• You may be applying too much side pressure
• The disc may be incompatible with the material
• Check that the flanges are properly installed

The cut is rough or jagged

• Reduce cutting speed slightly
• Apply lighter pressure and let the disc do the work
• Use a finer grit disc for smoother cuts
• Support the workpiece better to prevent vibration

The metal overheats and changes color

• Slow down your cutting pace
• Increase speed slightly for better chip clearance
• Use lubrication (cutting oil for metal)
• Take breaks between cuts to let things cool

The bit keeps getting clogged

• Switch to a diamond or silicon carbide disc for soft metals
• Clean the bit periodically during use
• Reduce speed for softer metals like aluminum

Recommended Hardell Products for Metal Cutting

Hardell 230-Piece Accessory Kit — Includes multiple cut-off discs, sanding drums, and polishing wheels. Everything you need for metal cutting, finishing, and polishing projects.

Hardell Diamond Cut-Off Disc Set — Premium diamond-coated discs that last 10x longer than standard discs. Ideal for cutting all types of metal cleanly.

FAQ

What is the best rotary tool for cutting metal?

For metal cutting, you need a corded rotary tool with sufficient power. The Hardell 12V Professional Rotary Tool provides the power and speed stability needed for consistent metal cutting results. Cordless models work for light-duty cutting only.

Can I cut a bolt with a rotary tool?

For small bolts up to 1/4" diameter, yes—with a diamond cut-off disc. For larger bolts or nuts, an angle grinder is much more practical and faster.

How do I prevent the cut-off disc from overheating?

Use steady, light pressure rather than forcing the cut. Take breaks every 15-20 seconds. For extended work, consider using cutting oil or a lubricant on the cut line. Never let the disc turn red-hot—that's a safety hazard.

Can a rotary tool cut hardened steel?

No. Hardened steel (like drill bits, springs, or hardened tool steel) cannot be effectively cut with a rotary tool. You need an angle grinder with an appropriate blade or a dedicated metal saw.

What speed should I use for cutting aluminum?

Use the highest speeds (25,000-35,000 RPM) for aluminum. Aluminum is very soft and clogs standard discs easily. Use silicon carbide discs and keep the bit moving to prevent clogging.

How do I get a straight cut with a rotary tool?

Clamp a straightedge (metal ruler, square, or straight piece of wood) to your workpiece along your cut line. Rest the edge of the rotary tool's footplate or body against the straightedge while cutting to guide your path.

Conclusion

Rotary tools are absolutely capable of cutting metal—you just need to match your approach to the material and thickness. For soft metals, thin gauges, and detailed work, a rotary tool is perfect. Save the angle grinder for heavy stock and structural metal.

The key takeaways: use the right disc, set the correct speed, apply light pressure, and prioritize safety. With these principles, you'll achieve clean, professional cuts on a wide range of metal projects.

Get started with a quality Hardell accessory kit that includes the cutting discs and bits you need for metalwork.