Cut metal like wood

Metal cutting circular saw blades can cut through metal faster, at less cost and cleaner than abrasive wheels. Metal-cutting blades for circular saws can work in wood-cutting saws, but more manufacturers are introducing units built to run at a lower rpm and collect the metal chips.

Several manufacturers are now offering carbide-tipped circular saw blades that cut metal with as little effort as it takes to cut wood.

Industry watchers report the blades have been around for a few years, but are now just catching on with a variety of trades.

“These blades are the newest kids on the block when it comes to cutting ferrous and nonferrous metals,” says Steve Rearick, technical specialist at The M.K. Morse Company. “The saws and blades cut much faster than any other method of cutting metal. They also have the added advantage of generating less heat while cutting.”

Available in sizes for cordless circular saws, corded circular saws and chop saws, the blades’ cutting tips are a combination of tungsten carbide, titanium carbide, cobalt or other carbide alloy mounted to a hardened steel plate.

“Carbide-tipped saw blades for wood are made out of C2 or C4 carbide. The metal-cutting blades use harder carbide – we use C7 which is much harder – in our Steel Pro metal cutting blade. Plus, the tips have a special grind and a zero hook angle,” says Kevin Ward, market manager for Primark Tool Group. “The blades cut non-hardened ferrous metals, galvanized steel, steel studs, composite materials, soild-surface materials, fiberglass, schedule 40 cast-iron pipe and rebar.”

Catching on
“Although these blades have been available, we must still demonstrate them so users understand their advantages,” says Jim Benton, DeWalt metal-working product manager. “While abrasive wheels are widely used to cut studs, users are finding these blades can cut other materials much faster and at a lower cost per cut.”

According to The M.K. Morse Company tests, the Morse Metal Devil blade can cut through 6" x 1/4"-thick steel plate in less than 12 seconds, typical for these types of blades. “They make a burr-free cut, which speeds installation because you don’t have to deburr the piece,” says Rearick.

When compared with a 14" abrasive wheel, which can make on average 60 cuts before it’s worn out, the 14" metal-cutting circular saw blade can make as many as 2,400 cuts.

“The metal-cutting circular saw blade is more expensive, but with its longer blade life, a cut with a metal-cutting circular saw blade costs four cents per cut, while the abrasive wheel cut costs nine cents per cut,” Benton says.

When metal is cut with one of these blades, heat is concentrated in the chip. That means metal can be picked up right after cutting. “Coatings on painted metal will not melt at the cut, leaving paint right at the edge. That’s especially helpful on prefabricated metal roofing and siding,” says Rearick.

Cordless saws gain attention
“The cordless metal-cutting circular saws are very popular with electricians who are cutting uni-strut, threaded rod or conduit. HVAC installers like them for cutting ducting and framers use them to cut 10- to 24-gauge studs,” says Benton.

The cordless 6 3/4" circular saw blades turn at about 3,100 rpm, which is much faster than a band saw, says Benton. “These tools can cut up to 2" black pipe and up to 1" threaded rod. They can cut 80 to 85 pieces of 1" conduit or 1/2" threaded rod on a single charge.”

Benton says cordless metal-cutting circular saws are gaining favor with tradesmen because they are lighter than a portable band saw. For example, the DeWalt DW934 cordless metal-cutting saw weighs 9 lbs., while a portable band saw weighs 17 lbs. “The cordless circular saw is easier to take to the work, especially on ceiling work,” he says.

Metal-cutting 7 1/4" circular saws
Many of the metal-cutting circular saw blades can be used in wood-cutting saws, says Ward. “They will work in saws that run 5,500 to 5,800 rpm and will cut up to 1/4" sheet steel, 1"-diameter rod or 1" square tube,” he says.

Saw manufacturers are coming out with circular saws specifically designed to cut metal, says David Hall of Porter-Cable, which offers a 13-amp saw that turns at 3,800 rpm.

“We have found that a slower-turning saw will cut metal faster than using a metal-cutting blade on a regular circular saw. It can cut metal up to 2 1/2" deep and 1/4" thick. The unit has a chip collector right on the tool that gathers up to 80 percent of the metal chips during cutting. These are very much a tool where you can just draw a line and cut, especially 20- to 18-gauge metal,” Hall says.

While abrasive wheels have long been used on chop saws to cut metal, carbide-tipped metal-cutting blades can cut faster, cooler and without burrs. For example, Makita offers a 12" metal cutting saw that can cut 4 1/2"-diameter steel tubing at 90 degrees and 3 1/2"-diameter tubing at 45 degrees. Makita tests show carbide-tipped metal-cutting blades can cut through a 2" x 2" x 1/4"-thick angle iron in three seconds; an abrasive wheel takes 12 seconds to make the same cut.

Ward says that cut-off saws using a 12"- or 14"-diameter blade run at about 1,500 rpm, which eliminates sparks while cutting.

“The entry into the material is slower than starting with an abrasive wheel, but it makes a cleaner, burr-free cut,” he says.

Published in the July/August 2003 issue of Contractor Tools and Supplies magazine.

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