Cut metal with the tool matched to its thickness: tin snips for sheet about 1-2 mm thick, a hacksaw for bar and pipe, a cold chisel for rivets and bolts, bolt cutters for rebar and chain of modest size, and an angle grinder only where you have power and full eye and face protection. Choose a hacksaw blade with at least three teeth touching the work at all times, which means finer teeth for thinner metal.
Part of Building Material Recovery
Salvaged metal arrives as sheet, bar, pipe, chain and bolts, and each form cuts best with a different tool. The wrong tool wastes effort and blades, and in some cases injures the user.
The Thickness Of The Metal Picks The Tool And The Blade
Hacksaw. The hand-powered workhorse for cutting metal. Keep spare blades because they wear out. Cut slowly with even pressure on the forward stroke only (parent article). The parent article pairs 18 teeth per inch with thin metal and 24 with thick; the usual machinist’s rule runs the other way, and this page follows it: finer teeth for thinner metal, coarser teeth for thicker metal, with at least three teeth in contact at all times so the teeth cut instead of catching and stripping.
Tin snips. For sheet metal up to 1-2 mm thick. Aviation snips come in left-cut, right-cut and straight versions. Essential for ductwork, roofing metal and flashing (parent article).
Cold chisel and hammer. For cutting bar stock, bolts, rivets and chain. Place the chisel on the cut line and strike firmly. It works on anything a hacksaw can cut, only less precisely.
Bolt cutters. For chain, bolts, padlocks, fencing, rebar and cable. The parent article gives a 60 cm cutter as handling up to 10 mm diameter hardened steel. Treat that as an upper limit and expect less on hard steel; if the jaws need all your weight, stop, or you may chip the jaws.
Angle grinder. With power and cutting discs, an angle grinder cuts steel in seconds, and the parent article judges it worth running a generator for heavy cutting. Always wear eye and face protection against sparks and disc fragments.
What You Need
- A vise or clamps, to hold the work.
- Hacksaw with blades of two or three pitches, snips, cold chisel, bolt cutters, files.
- Marker and square.
- Eye and face protection, gloves, hearing protection for grinding and chiselling.
- For a grinder: a guard fitted and a disc rated for the grinder’s speed.
Method: Hold, Mark, Cut, Deburr
Step 1: Identify the metal and its thickness; see Metal Type Identification.
Step 2: Clamp the work close to the cut so it cannot vibrate or jump.
Step 3: Mark the line and start with a notch made with a file.
Step 4: Choose the blade or tool. Count the teeth that will touch the metal; at least three.
Step 5: Cut. With a hacksaw use long, even forward strokes and lift slightly on the return. With snips cut along the line, not at the tip. With a chisel, strike squarely and keep the head free of mushrooming.
Step 6: Deburr. File off sharp edges and burrs.
Worked Example
The spacing of teeth, the pitch, is 25.4 mm divided by teeth per inch. At 18 teeth per inch the pitch is 25.4 ÷ 18 = 1.41 mm, so three teeth span 3 × 1.41 = 4.2 mm, which is the thinnest section that blade should cut square. At 24 teeth per inch, 25.4 ÷ 24 = 1.06 mm and three teeth span 3.2 mm. At 32 teeth per inch, 25.4 ÷ 32 = 0.79 mm and three teeth span 2.4 mm. Metal thinner than that is better cut with snips, or clamped between two boards and sawn through them.
Common Mistakes
- Using a coarse blade on thin sheet. The teeth catch and strip.
- Sawing on both strokes. It dulls the blade.
- Forcing bolt cutters. The jaws chip.
- Using a mushroomed chisel head. Fragments fly off.
- Holding a small piece in a gloved hand against a grinder. The work grabs and pulls the hand in.
Safety
Sparks, flying discs and cut edges
Angle grinders and cut-off discs throw sparks and can burst; wear eye and face protection, keep the guard on, use a disc rated for the grinder’s speed and stand clear of its plane. Never grind or cut near fuel, solvent vapour or gas, and never test for vapour with a flame. Sheared sheet edges and fresh cuts are razor sharp, so wear gloves and file the burrs. Cutting or grinding galvanised steel gives off zinc fume: work in the open air.
What’s Next
- Learn next: Copper Wiring & Plumbing — cutting and stripping copper
- Combine with: Grinding Wheels — wheel care and ratings