How to Cut Rebar with an Angle Grinder

If you’ve ever tried trimming steel rebar with basic hand tools, you know how tough it can be. That’s usually when the angle grinder comes to mind — compact, powerful, and easy to grab for quick jobs. But can it really handle cutting rebar cleanly and safely?

Absolutely. With the right disc, setup, and a few smart techniques, your angle grinder can slice through rebar in seconds. In this guide, we’ll walk you through everything you need to know — from preparation and safety tips to cutting steps and post-cut cleanup.

Quick Tool Comparison

Safety and Preparation Come First

Before you start, remember: rebar is tough steel, and grinders spin fast. A few minutes of preparation can prevent later regret.

Wear full protective gear—safety glasses or a face shield to protect from flying sparks, gloves for grip, long sleeves to block burns, and hearing protection for the noise. Always clear flammable materials from your workspace and have a fire extinguisher nearby.

Make sure your grinder guard is in place and your disc is in good condition (no cracks or chips). Rebar should be clamped securely so it won’t roll or pinch the disc. If you’re cutting a long piece, support both sides to prevent sagging.

Choosing the Right Grinder and Disc

Picking the right setup makes all the difference. A 4.5-inch grinder is ideal for small to medium jobs—like trimming rebar under 0.5 inch thick. For thicker or more frequent cuts, a 6" or 7" grinder provides more power and longer reach. Corded grinders deliver consistent torque, while cordless angle grinders win on portability.

When it comes to discs, only use metal-rated cutting wheels. Thin-bonded cut-off wheels are fast and inexpensive, but wear out faster. Diamond-tipped metal blades cost more upfront but last much longer—perfect if you’re cutting a lot of bars. Always check that the disc’s RPM rating matches your grinder. It’s the same trade-off—cost, usage frequency, and comfort—when deciding which disc or tool to buy.

Marking and Setting Up the Cut

Now that your tools are ready, measure the rebar carefully. Mark your cut line all the way around using chalk or a paint marker—this makes it easier to stay straight as you cut.
Place your rebar on a sturdy surface, like two sawhorses, and clamp one side firmly. Make sure the sparks will fly away from you and any flammable objects.

If you’re working indoors, improve ventilation or move outside; rebar cutting produces both sparks and fine dust.

Step-by-Step: How to Cut Rebar with an Angle Grinder

Start by holding the grinder with both hands and planting your feet shoulder-width apart for balance. Keep your body slightly to the side of the disc, never directly behind it.

1. Start the Grinder and Reach Full Speed
    Don’t touch the rebar until the grinder reaches full RPM. This prevents disc chatter and gives you a smoother start.
   

2. Make the Initial Cut
    Bring the spinning disc gently to the rebar at a slight 15–20° angle. Let the disc do the work—apply only light pressure. For thicker bars, you may need to rotate the rebar and finish from the opposite side for a cleaner cut.
   

3. Control Sparks and Finish the Cut
    Maintain steady pressure as you complete the cut. Avoid twisting or pushing the grinder, which can cause the disc to bind or break. Once through, let the cut piece fall safely or support it as it detaches.
   

4. Smooth the Edges
   Swap to a flap disc or grinding wheel and deburr the cut ends. It only takes a few seconds and makes handling rebar much safer.

Handling Real-World Job Situations

Sometimes rebar isn’t free on a bench—it’s tied into concrete or overlapping in a mesh. In those cases, use a thinner disc for easier maneuvering and protect nearby concrete with a scrap piece of wood or metal.
If you’re cutting dozens of bars for a large slab, set up a simple jig or stop block to make your cuts uniform. Take short breaks to prevent overheating both the tool and the disc. For projects with heavy repetition, switching to a chop saw or rebar cutter saves time and wear.

When cutting in tight spaces or indoors, keep sparks directed into a safe zone and have a helper on “fire watch.” Never cut near flammable materials, sawdust, or fuel.

Common Mistakes and How to Avoid Them

One of the biggest errors beginners make is using the wrong disc. Masonry, wood, or grinding wheels are not meant for cutting—they can shatter under stress. Always use a proper metal cut-off wheel.

Another mistake is forcing the cut. Pushing too hard overheats the disc, makes the grinder unstable, and leads to uneven results. Let the tool’s speed do the work.
Finally, never cut rebar that isn’t supported. A rolling or sagging piece can twist and trap the disc, which is both dangerous and damaging.

FAQs

1. Can any angle grinder cut rebar?
Yes, most 4½" or larger angle grinders can handle rebar with a proper metal-cutting disc.

6. What other power tools can cut rebar?
Besides an angle grinder, you can use:

• Chop saw or cut-off saw: Great for repetitive, clean, square cuts.
  

• Reciprocating saw (sawzall): Useful for cutting in tight spaces or when sparks are a concern.
  

• Portable rebar cutter: Fast and precise, perfect for jobsite professionals.
  

• Plasma cutter: Works on rebar, too, but it's usually overkill for small projects.

3. Why does my disc wear down fast?
Usually, it’s due to too much pressure or using low-quality discs. Let the grinder’s speed do the work instead of forcing the cut.

4. Can I cut rebar that’s already in concrete?
Yes, but protect nearby surfaces, use a thin disc, and work slowly.

5. Should I smooth the cut ends after cutting?

Absolutely. Smoothing with a flap disc or grinder edge removes sharp burrs, making the rebar safer to handle and easier to tie.

6. Is a chop saw better than an angle grinder?
For large batches or precision cuts, yes. For portability and quick jobs, the grinder wins.

Conclusion

With the right method, your angle grinder can cut steel bars quickly, cleanly, and effortlessly. The key is preparation—choose the right disc, hold the material, and take your time with each cut. Once you're operating it correctly, you'll be amazed at how easily an angle grinder can handle metal, even tough steel. Whether you're building, repairing, or just making minor adjustments, mastering this simple process will save you time and make your work look sharp and professional.