To cut steel angle or C-channel, mark the cut with a square on every face, clamp the piece so it can't move, and cut with a metal-cutting tool: an angle grinder with a cut-off wheel for a few cuts, or a chop saw, cold saw or band saw for straight, repeatable cuts. For a 45 degree mitre, the saw or vise is set to 45 degrees and both legs are cut in one pass. Torches and plasma cutters work but leave rough, heat-affected edges. If you need more than a handful of pieces, or the pieces are structural, ordering them cut to length from a fabricator is usually faster, more accurate and safer.
This post is about cutting new, loose material. Cutting a beam, lintel or channel that is already holding something up is a structural alteration; see can you cut or weld an existing steel beam first.
Tools for cutting angle and channel
| Tool | Best for | Cut quality | Watch for |
|---|---|---|---|
| Angle grinder with cut-off wheel | A few cuts, awkward spots, light sizes | Fair; hard to keep square | Wheel breakage, kickback, sparks |
| Abrasive chop saw | Repeated square cuts and simple mitres | Good, with a burr | Sparks, heat, wheel wear changes the cut |
| Cold saw (toothed metal-cutting blade) | Accurate square and mitre cuts | Very good, little burr | Blade must suit the steel and section |
| Portable or horizontal band saw | Clean cuts on larger sections, mitres | Very good | Slow on large sections; blade choice |
| Reciprocating saw with metal blade | Rough cuts, demolition | Poor | Vibration, wandering cut |
| Hacksaw | One or two cuts on light angle | Fair, slow | Tiring; keep the blade tensioned |
| Oxy-fuel torch | Heavy sections, demolition | Rough, needs grinding | Heat-affected edge, fire risk |
| Plasma cutter | Quick cuts on site, shapes | Fair to good with a guide | Bevelled edge, fumes |
Rebar cutters are not for angle and channel. Shears made for round bar won't cut an open section cleanly.
The metal-cutting chop saw and cold saw are the most common answers to how to cut steel angle iron accurately at home or on a small site. For a single cut on light angle, a grinder is fine as long as you take your time and keep the wheel straight.
How to cut steel angle
- Measure and allow for the kerf. Every cut removes a slice of steel the width of the blade or wheel. Mark the side of the line the cut goes on.
- Mark both legs. Use a combination square or speed square against the outside of each leg and scribe or mark the line around the piece. Rolled angle has a radius inside the heel and its legs are not always exactly 90 degrees apart, so square from the outside face of each leg.
- Clamp it. In a saw vise, or to a bench with the offcut free to fall away. Never hold the piece by hand.
- Cut steadily. Let the tool do the work. Forcing a cut-off wheel overheats it and makes it wander; forcing a band saw bends the blade.
- Deburr. File or grind the sharp burr off the cut edges, then check the length.
Our steel angle sizes chart has leg sizes and thicknesses if you need to confirm what you have.
Cutting 45 degree angles
Mitred angle is common on frames, curb angles and supports for openings. To cut a 45 degree angle in steel angle:
- Put one leg flat on the saw table and the other leg standing up against the fence.
- Set the vise or saw head to 45 degrees and clamp the piece.
- Cut through both legs in one pass. The flat leg gets the mitre; the standing leg is cut at the same angle so the two pieces meet at the corner.
- Mirror the setup (or flip the piece) for the matching part.
Cut a test pair from offcuts and check it with a square before cutting the real pieces. A one degree error on each piece becomes two degrees at the corner.
The alternative for frames is notch and fold: cut a V-shaped notch out of one leg, leave the other leg whole, fold it to 90 degrees and weld the seam. It gives a continuous outer leg and a neater corner.
How to cut C-channel
C-channel is harder to cut neatly than angle because the cut has to pass through two flanges and a web.
- On a chop saw or cold saw, set the channel with the flanges pointing down or on its back with the web against the fence, whichever lets the vise grip it firmly without the flanges flexing. Check the saw's capacity: deeper channels may not fit.
- On a band saw, clamp it so the blade enters a flange edge rather than taking the full web flat at once. That keeps the blade engaged and the cut straight.
- With a grinder, cut each flange first, then the web, working to lines marked on all three faces. It is slow and the cut is rarely perfectly square, so plan for grinding.
- Cutting steel channel lengthwise (ripping it into angles or trimming a flange) is a job for a plasma or torch with a straight-edge guide, followed by grinding. It changes the section, so don't do it to a structural piece.
Sizes and weights are in our C-channel size chart.
How to cut steel plate
For plate, a grinder or plasma cutter with a straight-edge guide handles short straight cuts; shapes, holes and thick plate are a shop job. Our post on steel plate cut to size in Ontario explains the cutting methods and how to order plate already cut and drilled.
Safety when cutting steel
Cutting steel produces sparks, hot chips, noise and, with abrasive wheels, the risk of a wheel breaking at high speed. The basics:
- Eye and face protection. Safety glasses under a face shield for grinders and chop saws.
- Hearing protection and gloves that won't catch in the tool.
- Match the wheel to the tool. The cut-off wheel's speed rating must be at least the grinder's maximum speed, and the guard stays on.
- Clear the spark path. Move anything flammable, watch where sparks land, and keep watch after you finish. On a construction site, follow the site's hot work rules, which often include a permit and a fire watch.
- Ventilation. Cutting galvanized or painted steel produces fumes. Work outdoors or with extraction, and avoid torch cutting galvanized material where possible.
- Support the offcut. A falling offcut or a piece that pinches the blade is how most injuries happen.
Finishing cut ends
A raw cut end is the first place rust starts. After cutting:
- Deburr and clean the edge.
- Prime and paint cut ends on painted steel.
- Touch up galvanized steel with a zinc-rich repair coating, because cutting removes the zinc at the cut.
For pieces exposed outdoors, it is better to cut and drill first and galvanize after, so the coating covers every edge. See does structural steel need paint or galvanizing.
When shop cutting makes more sense
DIY cutting is fine for a bracket, a shelf support or a few pieces for a non-structural project. A fabricator is the better choice when:
- You need more than a few pieces, especially identical ones.
- Accuracy matters, for example angles that must fit an opening or match existing work.
- The steel is structural. Lintels, ledgers, beam seats and posts should be cut, drilled and welded to a detail, not field-fitted.
- The section is heavy. Large channels and thick angle are slow and hazardous to cut with hand tools.
- You need holes, slots, copes or welded plates as well as cuts.
- You want a finish. Shop priming or galvanizing after fabrication protects cut edges properly.
Angle and channel cut to your sizes
We supply steel angle, C-channel, plate and beams cut to length or fully fabricated to your drawings, with holes punched or drilled, plates welded on in our CWB certified shop, and priming or galvanizing to suit. Angle lintels can be cut to length and punched or welded as needed.
Send your cut list or drawings for a quote, or see our services for fabrication and delivery across the GTA and Ontario.
Frequently asked questions
What is the best tool to cut steel angle?
For a few cuts, an angle grinder with a metal cut-off wheel. For repeated square or mitred cuts, a metal-cutting chop saw, cold saw or portable band saw gives straighter, more accurate cuts. Torches and plasma cutters work but leave rougher edges that need grinding.
How do you cut a 45 degree angle in steel angle?
Lay one leg flat on the saw table with the other leg standing against the fence, set the vise or saw to 45 degrees, clamp it, and cut through both legs in one pass. Mark both legs with a square first and cut a test piece, because a small angle error doubles when two pieces meet.
Can you cut C-channel with a grinder?
Yes, but it takes several cuts (each flange and then the web) and keeping them square is hard. A chop saw, cold saw or band saw with the channel clamped firmly gives a cleaner cut. Wear eye and face protection and clear anything flammable from the spark path.
Can I cut a steel lintel or channel that is already installed?
Not without an engineer's say-so. Shortening, notching or cutting holes in a member that carries load changes its capacity, and the building usually needs temporary support while it is done. Treat it as a structural alteration.
