Cutoff Wheel

What is a cutoff wheel?

A cutoff wheel is a thin, round disc that attaches to power tools to make straight cuts by grinding through material along a narrow path (the kerf). Unlike grinding wheels that shape or smooth surfaces, cutoff wheels are made only for slicing. They come in abrasive-bonded or diamond-tipped versions and must be matched to the tool’s speed rating and the material you’re cutting.

How it works

Cutoff wheels remove material with countless sharp particles bound together on the wheel’s edge. As the wheel spins at high speed, those particles shear off tiny bits of the workpiece. Thin wheels cut faster and leave a smaller kerf, which reduces heat and effort. The tradeoff is they’re more fragile. Diamond cutoff wheels use industrial diamonds bonded to a metal rim; they last longer on very hard materials like tile, stone, and concrete.

Common DIY uses

• Trimming bolts, screws, and threaded rod flush
• Cutting rebar, angle iron, and steel pipe
• Removing rusted fasteners that won’t budge
• Scoring and cutting ceramic tile or stone (diamond wheel)
• Cutting masonry or pavers (masonry/diamond wheel)
• Slicing sheet metal for ductwork or brackets
• Small precision cuts in plastic or metal with a rotary tool

Note: Avoid using abrasive cutoff wheels on wood. They can grab and kick back. Use a saw blade designed for wood instead.

Types and variations

• Abrasive-bonded wheels (resin bonded)
  • Metal-cutting: Aluminum oxide is common for carbon steel. Look for INOX or stainless-rated wheels that contain no iron, sulfur, or chlorine if you’re cutting stainless steel.
  • Non-ferrous metal: Wheels labeled for aluminum or non-ferrous resist loading (clogging). A cutting wax or stick lube can also help.
  • Masonry: Silicon carbide wheels for concrete, brick, and stone.
• Diamond cutoff wheels
  • Continuous rim: Smooth edge for wet or dry tile cutting with clean edges.
  • Turbo rim: Slightly serrated for faster cuts with decent finish; good for stone and masonry.
  • Segmented rim: Fastest on concrete and pavers; rougher cut and more chipping on tile.
• Sizes and formats
  • Angle grinder: 4-1/2 in (115 mm) diameter is common, with 0.040–0.060 in thickness and 7/8 in (22.23 mm) arbor. 5 in (125 mm) and 6 in (150 mm) are also used.
  • Chop/abrasive saw: 12–14 in wheels, typically 1/8 in thick.
  • Die grinder: 2–3 in wheels with 3/8 in or 1/4 in arbor/mandrel.
  • Rotary tool: 1 in (approx.) reinforced discs or mini diamond wheels.
• Profiles
  • Type 1/41: Flat cutoff wheel (most common for cutting).
  • Type 27: Depressed center; some are marketed for cutting, but many are grinding-focused. If you need to cut, choose a wheel labeled for cutting.

Choosing the right cutoff wheel

• Match the material
  • Steel: Aluminum oxide, or a wheel labeled for steel.
  • Stainless: INOX/stainless-safe wheels (contaminant-free).
  • Aluminum and soft metals: Non-loading wheels; consider lubricant to reduce clogging.
  • Tile, stone, concrete: Diamond wheels (choose rim style based on finish vs speed).
• Check speed rating
  • The wheel’s maximum RPM must be equal to or higher than your tool’s no-load speed. Never exceed the wheel’s rating.
• Pick thickness for the job
  • Thin (about 0.040–0.045 in): Fast cuts, less heat, cleaner edges on sheet and thin stock.
  • Medium (about 1/16 in): General purpose on a range of metal thicknesses.
  • Thick (1/8 in and up): More durable on chop saws and for heavier sections; slower cut.
• Size and arbor
  • Use the correct diameter and arbor hole for your tool and guard. Do not modify flanges or guards to “make it fit.”
• Reinforcement
  • Look for fiberglass-reinforced wheels for handheld tools to reduce breakage risk.

How to use a cutoff wheel safely and effectively

1. Prepare the work area
   • Clear flammables from the spark path; have a fire extinguisher nearby.
   • Secure the workpiece with clamps or a vise. Never hand-hold small parts.
2. Inspect the wheel and tool
   • Check for cracks, chips, warping, or moisture damage. Do not use damaged or expired wheels (look for date codes on the blotter/label).
   • Ensure the guard is installed and correctly positioned to deflect sparks.
   • Verify the flanges are clean and flat; tighten per the tool’s instructions.
3. PPE
   • Safety glasses plus a face shield, hearing protection, gloves, long sleeves, and a proper dust mask or respirator for metal or silica dust.
4. Start-up
   • Stand slightly off to the side of the wheel’s plane.
   • Let the tool reach full speed before contacting the work.
5. Technique
   • Align the cut and use a steady, straight feed. Apply light pressure; let the wheel do the work.
   • Keep the wheel perpendicular to the cut. Avoid twisting, prying, or side-loading.
   • For long cuts, make a shallow score first, then deepen it. This helps control and reduces wandering.
   • Manage heat: pause between passes or use thinner wheels to reduce bluing and warping on metal. For tile, consider water (if your tool and wheel allow) to keep the cut cool and control dust.
6. After the cut
   • Wait for the wheel to stop completely before setting the tool down.
   • Store the wheel in a dry, flat place if it’s removable and still usable.

Care and storage

• Keep wheels dry and avoid extreme humidity or direct sunlight; resin can degrade.
• Store flat, in the original packaging, away from heavy loads that could warp them.
• Don’t “ring test” thin resin-bonded cutoff discs; they don’t respond the same way as thick vitrified wheels. Instead, inspect visually and flex very gently with gloves to spot cracks.
• Separate wheels by material to prevent cross-contamination (especially for stainless work).

Common mistakes to avoid

• Exceeding RPM limits or using the wrong diameter for the tool.
• Removing or repositioning the guard for better visibility; use proper guards and better lighting instead.
• Side-grinding with a cutoff wheel; use a grinding wheel or flap disc for that task.
• Forcing the cut, which overheats the wheel, causes glazing, and increases kickback risk.
• Using a metal wheel on masonry (or vice versa), leading to rapid wear and poor results.
• Cutting aluminum with a steel wheel without lubricant or a non-loading spec; the wheel clogs and grabs.
• Letting the wheel wear down too far on a grinder; a tiny disc changes handling and may not be covered by the guard.

Related terms

• Angle grinder, die grinder, rotary tool
• Abrasive saw (chop saw), cut-off saw
• Grinding wheel, flap disc, diamond blade
• Arbor, flange, guard, kerf, kickback, RPM

Practical examples

• Cutting a rusty bolt: Clamp the work, fit a 4-1/2 in x 0.045 in metal wheel, approach square to the bolt, score, then finish the cut. Follow with a file to deburr.
• Trimming rebar: Use a 14 in abrasive saw with a 1/8 in wheel or a diamond segmented wheel on a concrete saw. Mark length, support the off-cut so it doesn’t pinch, and feed steadily.
• Cutting a tile notch: Mount a continuous-rim diamond wheel. Mark the outlet box, score along the lines, and make several shallow passes. Use water if the tool and wheel are rated for wet use.
• Shortening aluminum angle: Choose a non-ferrous wheel, apply a light wax to reduce loading, and make slow, straight passes with minimal pressure.

A cutoff wheel is a small component with a big impact on cutting quality and safety. Match the wheel to your material and tool, follow good technique, and you’ll get faster, cleaner results with less drama.