Can you cut sheet metal with a circular saw?

Cutting sheet metal is a common task for many DIYers and professionals. While specialized tools like a sheet metal shear or nibbler are ideal for cutting thin sheets of metal, many wonder if they can get away with using tools they already own like a circular saw. There are some important considerations when attempting to cut metal with a circular saw, but it is possible under the right conditions.

The Short Answer

Yes, you can cut thin sheet metal with a circular saw. However, there are limitations and precautions you should take. A standard framing blade on a circular saw is not ideal for cutting sheet metal, but with the right blade, adjustments, and techniques, circular saws can be used to make cuts through thin steel, aluminum, and other metals up to about 18 gauge thickness.

Challenges of Cutting Metal with a Circular Saw

Cutting sheet metal poses some unique challenges compared to cutting wood with a circular saw:

• Metal is harder on blades – The tough, abrasive surface of metal can wear down standard framing blades very quickly.
• Thinner material requires slower speeds – High circular saw speeds designed for fast wood cuts can bend and deform thin sheets of metal.
• Metal conducts electricity and heat – This can lead to dangerous kickback when cutting.
• Metal needs lubrication – Friction from an unlubricated blade causes excess heating of the metal.
• Metal chips present hazards – Small sharp metal chips produced while cutting should not be ignored.

Cutting thin metal sheets with a power saw that is not designed for that purpose requires precautions. But with the right approach, this common saw can be adapted to cut metal successfully.

Choosing the Right Blade

The most important consideration when preparing to cut metal with a circular saw is choosing the proper blade:

• Use a blade specifically designed for cutting metal – Look for carbide tipped blades marked for non-ferrous metal cutting. The carbide tips will last longer than standard teeth.
• Minimize teeth – Blades with fewer large teeth spaced farther apart, such as 24 teeth, cut better than blades with more smaller teeth designed for plywood and fast wood cuts.
• Chose an appropriate TPI – For thin steel, aluminum, or sheet metal, a blade with 14 to 18 teeth per inch (TPI) works best.
• Consider a cold cut saw blade – These blades have a ground tooth design optimized for cutting sheet metal with reduced friction and heat buildup.

Using the wrong blade will make cutting difficult, produce rough edges, and quickly ruin an expensive framing blade. Investing in the right metal cutting circular saw blade will produce the cleanest cuts.

Adjusting Saw Speed

Circular saw motors spin the blade very fast, which is ideal for making quick, clean cuts in wood. But for thin metal, slower speeds are required.

• Refer to your saw’s manual for speed adjustment – Variable speed saws often have a dial or settings for reducing blade RPM for metal cutting purposes.
• If no adjustment, trigger control is key – Pull the trigger gently so the blade spins slower than full speed.
• Target blade speeds around 1,500-2,000 RPM – Faster speeds may bend, deform, or ruin thin sheet metal.
• Slower feed rate required – Move the saw more slowly through the metal at reduced speeds.

Proper Technique

Along with equipment considerations, using proper technique when cutting metal with a circular saw is crucial for control, safety, and good cuts:

• Use clamps or a vice to secure metal – This prevents vibration, bending, or slipping during cuts.
• Mark cut lines clearly with a permanent marker.
• Put on safety glasses and gloves – Protect yourself from sharp flying shards of hot metal.
• Use light pressure – Let the blade do the work without forcing through material.
• Lubricate the blade – Apply cutting wax or light oil to reduce friction, smoking, and burns.
• Support both sides of metal near the cut – Prevents binding and chatter which wears down blades.
• Keep blade RPMs constant during cut – If needed, pause saw to adjust speed before continuing cut.
• Allow time for cool down between cuts – This gives thin metal time to dissipate heat.

Rushing the process or using excessive force leads to poor cuts, dangerous conditions, and blade damage. Work slowly and carefully for best results.

Safety Tips

Any power saw can be dangerous, and cutting sheet metal adds unique risks. Keep these safety tips in mind:

• Wear eye protection – Flying debris can cause eye injuries.
• Use hearing protection – Cutting metal is loud.
• Wear gloves – Avoid cuts from sharp metal and abrasive blades.
• Wear long sleeves – Protect arms from sharp flying chips and burns.
• Use a respirator – Metal dust is unhealthy to inhale.
• Unplug saw to change blades – Accidental startup could cause injuries.
• Beware hot blades after cutting – Metal conducts and retains heat.
• Clean up metal chips – They can cut bare feet long after cutting.
• Follow electrical safety – Avoid cuts to cords or risk of shock.
• Secure metal workpiece – Prevent movement, vibration, or slipping.

Respect for power tool hazards and sharp sheet metal edges will help avoid serious and painful injuries.

Limitations

While it is possible to cut thin sheet metal with a circular saw, there are some limitations to note:

• Not practical for long cuts – Circular saws are best for shorter straight line cuts rather than following a curve.
• Not for thick, heavy-gauge metal – Standard circular saws lack power and torque for steel plate over about 18 gauge.
• Limited thickness capacity – Can only cut up to about 3/16 inch thick metal.
• Not suitable for hardened tool steel – Very abrasive on carbide blades.
• Poor precision and straightness – Freehand circular saw cuts often wander.
• Rough cuts with tear out – Blades lack fine finish of shears or nibblers.
• Produces sharp dangerous chips – Requires care compared to tubing cutters on pipe.

For thicker materials, long cuts, precision, or high production metal cutting, a dedicated metal cutting bandsaw, chop saw, or other tool designed specifically for metal would be a better choice. But for occasional, quick, short, straight cuts in thin sheet metal, circular saws can get the job done.

Best Practices

Follow these best practices when attempting to cut metal with a handheld circular saw:

• Choose an appropriate saw – Corded circular saws have more power and control for metal cutting than cordless models.
• Select the right blade – Carbide tipped metal cutting blades between 14 and 18 TPI are best.
• Adjust speed as needed – Target 1,500-2,000 RPM for thin metal workpieces.
• Always clamp workpiece securely – This prevents bending, vibration, or slipping during cuts.
• Use cutting fluid – Lubricate blade to minimize heat buildup.
• Make relief cuts if needed – When cutting large panels, relieve tension to prevent binding.
• Support both sides near blade – Reduces chatter for clean cuts.
• Let blade stop before repositioning – Avoid blade damage or grabbing.
• Unplug when changing blades – Guard against accidental startup.

Exercise caution, work slowly, and follow all safety practices at all times when attempting to cut metal with a power tool designed primarily for wood. But with care, it is possible to adapt a circular saw to handle occasional metal cutting jobs.

Frequently Asked Questions

Can I use a framing blade to cut thin sheet metal?

It is not recommended to use a standard framing or wood cutting blade on a circular saw to cut sheet metal. The thin, hard metal will quickly wear down and damage the teeth of blades designed for cutting wood. Always use a blade specifically made for cutting non-ferrous sheet metal when cutting thin steel, aluminum, etc.

What thickness of sheet metal can be cut with a circular saw?

A standard 7-1/4 inch circular saw can typically cut sheet metal up to about 18 gauge thickness, or around 1/16 inch thick. Any thicker and the saw is likely to lack the power to make an effective cut.

Can I cut galvanized sheet metal with a circular saw blade?

Yes, circular saw blades made for non-ferrous sheet metal cutting will cut galvanized sheet steel. However, the zinc galvanized coating is very abrasive, so expect accelerated wear on the teeth. Lubricating the blade is highly recommended, and touch up grinding or replacement will be needed more frequently.

What RPM should I run a circular saw at for cutting thin metal?

The ideal RPM for cutting thin sheet metal with a circular saw is around 1,500 to 2,000 RPM. This slower speed is necessary to prevent deformation of thin metal workpieces. Adjust your saw’s variable speed dial, or gently squeeze the trigger, to aim for these approximate speeds.

Can I cut metal roofing with a circular saw?

Yes, it is possible to cut corrugated metal roofing or siding sheets using a circular saw fitted with an appropriate non-ferrous metal cutting blade. Maintain slow speeds and secure the panel to prevent vibration. Support near the cut to avoid binding and use lubricant. Make relief cuts on large pieces.

Conclusion

While an angle grinder with a cutoff wheel or reciprocating saw with a metal blade would be better choices for cutting thick steel stock, sheet metal up to 18 gauge can be cut with a standard circular saw using the proper precautions and techniques. The limitations must be recognized, but with care, setup, and the right blades, circular saws can occasionally be used to make basic straight cuts through thin aluminum, steel, and other sheet metal for the average DIYer.