Hard cuts, hard choices

Portable concrete saws take on tough cutting tasks. Make it easier on the operator – and the saw – by selecting the right-sized saw for the job.

It’s one of the most grueling of construction jobs: cutting concrete with a portable gasoline-powered saw. The power it takes to turn a diamond saw blade through a cut and the dust produced by the cut adds up to be a demanding work environment for the two-cycle engines that power these units, as well as the operator.

Contractors can make these tough cuts a bit easier by getting the right equipment to do that job, says David Schwartz,  industrial tool product manager at Stihl, Inc. “These machines take a beating on the job. They must be able to stand up to some of the worst operating conditions on a jobsite,” he says.

Size matters
Although cutting concrete takes some significant power and performance, bigger is not always better, says Leif Persson, technical manager at Partner Industrial Products. “Use the appropriate sized saw for the job. If you are doing only shallow concrete, metal or masonry cutting, a lighter, 12" saw may be the best choice. But if you must make concrete cuts as deep as 6"  then a larger saw that can handle 16" blades may be the better choice,” he says.

Schwartz concurs. “As diamond saw blades have come down in price, there has been a tendency to go with a larger saw that can handle the larger blades. The [false] reasoning is that the bigger saw and bigger blade will make the cut faster. Before you upgrade to the next saw size, ask yourself if you really need all that extra power and weight that comes with it?

“Even though workers who operate concrete saws are strong guys, there is a big difference in fatigue between working with a 20-lb. saw vs. a 32-lb. saw. If you are only cutting 1/2" expansion joints, a lighter saw is the better choice. Also, the larger saws consume more fuel, and over time that adds up to higher saw operating costs.”

“Weight of the saw is an important consideration,” says Trey Brown, Makita national sales manager of outdoor power equipment, “How the tool balances during the cut also makes a big difference. We have found the most popular size for contractors is the 14" unit with a 73 cc engine. It has the power for jobs up to almost 5" deep.”

Brown cautions users from getting carried away with using displacement as a measure for power. “KW or horsepower are a better gauge of a tool’s power, but there also different ways to measure horsepower, so don’t base your decision totally on that one specification,” he says.

Three saw options
There are three distinct types of portable concrete saws that make up an interesting combination of tools for a variety of concrete cutting jobs, says Scott Swidler, marketing assistant at Partner Industrial Products. For cuts as deep as 5", the circular diamond blade saws are the most economical and popular choice, he says. “But if you have a job on a foundation, which is usually thicker than 5", a 14" blade with a 5" cutting depth isn’t practical. This is where a concrete chainsaw or ring saw comes into play.

“A 14" ring saw can cut up to 10" deep and can make the cut at one-third the cost of a chainsaw,” says Swidler. “We are recommending users to cut the corners of deep cuts with a chainsaw, then do the long cuts with a ring saw. The ring saw will cut the concrete in one third of the time of a chain saw.”

“If you are cutting through material that is more than 10" thick, a concrete chainsaw is a good option. They can cut as deep as 15" and make nice, square corners without over-cutting and can create openings as small as 4 3/8" x 4 3/8". They can also be used to plunge-cut in concrete pipe. However, cutting with diamond chain is the most expensive option for cutting,” he says.

Ask around
The best way to select a new saw is to ask others how they like the models they use, especially if they use a different brand or model than the one you have used. “With these saws, you really get what you pay for. Durability is a good measure as well as how operators like using the saws. Also, ask them how easy it is to maintain it. Experience goes a long way with these saws. When users find a saw they like, they won’t give it up,” ” says Schwartz.

Maintenance key to long saw life
The saw experts agree that maintenance is the key to saw uptime. However, the extreme operating conditions and heavy loads that these saws take, they do wear out. But maintenance can greatly extend saw life.

“It’s possible for saws to last as long as eight years, but average saw life is between one and two years. Poor maintenance practices can lead to saws lasting only three months,” says Schwartz.

For longer life, Schwartz says starting with a high-quality two-cycle oil additive is important. “The difference may only be 50 or 75 cents, but it can greatly affect the life of the engine. You can pay now or pay later.”

Proper air filtration is a must with these saws. Most saw models have some sort of triple filtration system that takes out the large particles first, then catches microscopic particles in an oil/sponge or paper filter. A spit-back filter between the secondary filter and the carburetor catches any extremely small particles and prevents any gas/oil fuel mixture from spitting back into the air cleaner. Fuel spitback into the second filter will clog it and effectively suffocate the engine.

“Follow what the manufacturer recommends for filter changes, and listen to the saw’s performance as a sign that filters need attention,” says Schwartz, “When changing filters, keep the dirt out of the filter and the engine.”

“Workers are always pressed for time and may be tempted to run the tool until it doesn’t work when the unit is hard to maintain,” says Brown, “Maintaining the filter is critical. Adhere to the recommendations of the saw’s manufacturer.”

Click here to see Diamond saw specs

Published in the January/February, 2004 issue of Contractor Tools and Supplies magazine.

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