Cutting aluminium and plastics on a bandsaw.

A bandsaw can cut more than wood, but not every bandsaw can cut everything. The deciding factor is blade speed: woodworking saws run their blades very fast, metal-cutting saws slowly. Soft non-ferrous metals and many plastics sit in between, so whether your saw can cut them depends on its speeds, its blade and what the manufacturer allows.

Why speed matters.

At wood speeds, a blade’s teeth rub steel instead of cutting it and are dulled in moments. Blade suppliers give much lower speeds for metal. Sawblade.com’s chart, for example, suggests about 250 ft/min (76 m/min) for mild steel and 120 ft/min (37 m/min) for stainless steel in small sections, and notes that its chart can’t take every factor into account. Aluminium and brass are cut faster than steel, but still far slower than wood. See bandsaw blade speed explained.

Aluminium and brass.

• Speed. Use the lowest speed your saw offers, or a metal-cutting saw if you cut metal regularly.
• Blade. A bi-metal blade with a fine pitch, so at least three teeth are in the material; see choosing TPI. A blade used on metal is no longer good for fine woodwork, so keep it for metal.
• Lubricant. Aluminium sticks to the teeth and clogs the gullets. A stick lubricant or cutting wax applied to the blade helps.
• Hold it firmly. Clamp small pieces or use a carrier board; metal parts can catch and spin.
• Deburr. Cut edges are sharp; file or sand them.

Plastics.

• Heat is the enemy. Many plastics melt at the cut and weld back together behind the blade. A coarser blade, a slower speed and a steady feed help.
• Acrylic can chip; keep the protective film on and support the sheet close to the cut.
• Dust and fumes. Plastic dust is fine and some plastics give off fumes when they overheat. Use extraction and ventilation; see dust extraction.

Steel and iron.

For steel, use a metal-cutting bandsaw or a portable band saw, which run at metal speeds with bi-metal blades. See blades for small metal-cutting bandsaws and cutting with a portable band saw.

Sources

• Sawblade.com, “Band saw blade speed and feed chart”.