Make quality concrete cuts

Cutting concrete is demanding enough without contending with mechanical problems and failures. Contractor Tools and Supplies interviewed several concrete saw manufacturers for their insight into common concrete saw equipment problems and what contractors can do to head them off.

The experts agree that proper saw and blade selection followed up with preventive maintenance are keys to effective sawing.

They offer the following tips to help you get efficient, quality cuts in concrete.

Selection tips
“Identify what you are cutting,” suggests Ed Varel, project manager at Stone Construction Equipment. “Is it green concrete, cured concrete or asphalt? You need to know that to select the right blade for the job.”

Once you know the material you’re cutting, select the correct size and type of concrete saw for the job. Several styles are available: Handheld saws are great on a variety of smaller jobs; walk-behind units are built to make flat cuts safely and efficiently and wall saws are used on bigger jobs to remove portions of walls.

Varel suggests looking at saw capacity when selecting a saw. “Smaller jobs or specialized finishing applications may be more suited to a push-type saw, but a self-propelled unit may be a time-saver,” he says.

The next step requires you to match the blade to the saw. “Can the saw handle the blade you want to use? Dry-cut blades have certain requirements and wet-cut blades can only be used on saws that can deliver enough water pressure to the saw,” says Varel.

Knowing the depth of the cut is a key part of the saw and blade selection process, adds Stan Levy, national sales manager at Partner Industrial Products. Although a blade is designed to make an 8" cut, that doesn’t mean it will do it one pass. The experts agree that it’s best to cut no more than 3" per saw pass.

Saw set-up on the jobsite
Varel says the jobsite foremen must make sure the worker is properly trained to operate the saw. “They should understand all safety devices on the machine and understand the factors that affect cutting efficiency,” he says.

Once you’ve selected the saw and blade for the job, the experts advise the operator double-checks to assure the blade is fastened correctly and the saw will operate at the proper speed.

Kevin Cote, technical field representative at Diamond Products says saw operators often make the mistake of running a 36" blade at a speed setting for 20" blade. “They think a faster speed will yield a faster cut, but spinning the blade too fast can result in blade glazing and slower cutting,” he says.

Smaller saws have charts that match appropriate running speed to the saw blade size. Larger saws require users to change the engine governor and pulley sizes to get the right blade speed. “You should use a shaft tachometer or a digital tachometer to double-check shaft speed. The saws are easy to switch from speed to speed, so it’s important to check that the speed is correct for the blade you are using,” he says.

Varel suggests operators complete a once-over inspection before using the saw. Check common maintenance items and look for worn, missing or broken parts such as blades, air filters, shock mounts, belts or guards. “If you get special instructions on what it takes to get the tool started or are told to let it warm up or jiggle controls, the unit probably needs service,” he says.

Making the cut
Once you have mounted the blade and set the speed, the experts suggest operators review the work area and make any necessary markings. The operator and any other workers in the area should be outfitted with the proper personal protection (PPE) equipment. Refer to the operator manual for specific PPE requirements.

“The operator should record how many linear feet are cut between blade changes. Keeping track of cutting performance can help you gauge whether you are getting good performance. If a blade’s production drops, it’s time to check settings or if there was a change in concrete hardness. You may need to change to a different blade or adjust speed. You won’t realize you need to make changes if you don’t keep records,” Cote says.

Maintain the unit for top efficiency
“Concrete saws are tough, but they are precise pieces of equipment that need ongoing maintenance to operate safely and efficiently,” says Cote.

Partner’s Levy concurs. “Today’s handheld saws are more reliable with longer service intervals. In the past, operators had to complete maintenance on saws every four hours, but newer saws with improved filter technology allow them to keep working for as long as a month without a filter change. Saws that came back to the shop every two weeks for repairs now don’t come back for months,” he says.

Because air filters on concrete saws perform better and can run longer before changeout, Levy says other items may begin to perform poorly or fail between maintenance checks.

“Workers need to watch for items showing wear, such as pull ropes or belts,” says Levy. “With portable concrete saws, users pull the starter rope 20 to 30 times a day. The abrasive concrete dust gets inside the braided cord and slowly cuts the fibers. If a saw is inoperable because a low-cost part like a rope breaks, it’s still as useless on the jobsite as a saw with a major mechanical failure. That’s why maintaining minor, inexpensive wear items is as important as timely service of other components,” he says.

Levy cautions against using low-cost lawnmower rope as a replacement rope on concrete saws. “Inexpensive cords have a wide braid that allows dust to penetrate the rope. Every pull abrades the rope and it will fail faster than a high-quality rope,” he says. Levy recommends replacing ropes as a part of routine maintenance.

Plan for daily service
Diamond’s Cote suggests users service walk-behind saws at the end of the day, especially when it comes to lubricating bearings. “When you grease bearings at the end of the day, the unit is warm and allows the grease to better penetrate the bearing,” he says. “When the unit is cold, the grease doesn’t spread through the bearing as readily.” Operators should check the unit’s hardware for tightness and the belt for tension.

Varel suggests workers request repair for equipment that shows any of the following maintenance signs:
• Excessive oil or fuel leaks
• Engine is hard to start
• Engine lacks power
• Engine cuts out/stalls
• Unit needs special “coaxing” to start it or          keep it running
• Excessive wear or cracks in blades, air filters, shock mounts or other components
• Loose hardware anywhere on the machine

Published in the March/April 2001 issue of Contractor Tools and Supplies magazine.

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