Masonry Magazine June 2002 Page. 20
Cover
STORY
Matching the blade to the saw motor capacity isn't as critical in brick saws as with some other applications.
can be very hard and require a special blade, often best used on a higher horsepower saw, something in the 5 hp to 7 hp range in electric and 13 hp in gas. They'll work on the common 1.5 hp to 2 hp saw but cutting won't be as fast."
Yes, size does count
AS WITH SO MUCH, compromise is the key to picking the size (diameter) of the blade. If you are cutting one type of unit, there are blades designed to do that without compromise.
Contractors will often buy the 20-inch saw and use it with a 14-inch blade for cutting brick and switch to the 20-inch blade for block so they can cut the block in one pass. As Lundberg says, "It's crazy to use a 20-inch brick blade with the ability to cut 8 inches deep when you only need to cut 2.75 inches deep. You've paid for all that depth capability and the diamonds on the blade-but aren't using it. Stock 14-inch brick blades even if you buy the 20-inch saw."
However, that's not a universally accepted practice. Offering a counterpoint is Delahaut: "The problem with a 14-inch blade on a 20- or 24-inch saw is that the rpm will be reduced significantly. This is not a good thing for a diamond blade that is designed for 3,800, not 2,270 rpm. The speed drop is significant enough to cause the blade to be ineffective or to glaze over, something that happens all too frequently."
Some contractors will do this so that they don't have to have two saws, both 14- and 20-inch models. This does not mean that they are using the tool the way it was designed. "In most cases when a contractor does use a 14-inch blade on 20-inch masonry saws, the performance of the blade is called into question and the manufacturer is contacted to address the issue. Maintaining the correct speed is critical in any application."
Blades are designed to run optimally at a certain surface speed, expressed in feet per minute. While you can use a 14-inch blade-or even a 12-inch blade in an emergency-on a saw designed for a 20-inch blade, as Delahaut says, the result can create problems. If you are going to use a 14-inch blade on a 20-inch saw, changing out the pulleys to match the specific rpm is a must. Most manufacturers will specify the right size pulleys and belt combination if you intend to use a 14-inch blade.
Lundberg explains why. "When you put a smaller blade in a 20-inch saw," he says, "it runs at a slower surface speed. With a diamond blade that makes it act 'softer. It will actually cut very nicely but wear out much faster than a 20-inch blade in the same application. Still, why buy a 20-inch blade, and pay for all that extra cutting depth, when you only need to cut 2 inches deep?"
Since the saw itself is a long-term investment-some contractors are using saws that are more than 20 years old and still functioning fine-while the blade is a disposable element, over specifying the saw can be a smart move. Over the years, with the variety of jobs a contractor might take on, having the largest, highest quality saw available can be a cost savings. When many saws are purchased, picking a variety of sizes and motor configurations would be reasonable. A smaller contractor might benefit more from the versatility of the 20- to 24-inch saws now available.
Lundberg adds, "A saw is a long-term investment but the blades, they're a commodity. You want to get the best blade with the longest life you can get. Many masons are using hand-held high-speed saws to cut brick-I know some companies that will have 25 high-speed saws, and no or only one brick saw. If you get 14-inch blades for those handhelds, they can also be used on your masonry saw. Typically they don't have as good a life, but you don't have to buy 2 blades."
It's all in the wrist
THE BRICK SAW IS accurate and that accuracy is highly repetitive because it is a stable platform with precision components. The masonry unit is held on a moving shuttle that allows the worker to align the unit with the blade for an accurate cut. But in some ways, that simplicity has made a difference in how the saw is worked.
Delahaut recalls, "The action of the worker should be cut, pull, cut, pull. It's a technique that, in many cases, has become a lost art. In the 50s, they had to do that because the blades were designed with a brazed bond that held the segment on. You couldn't have the blade in the masonry material too long without some cooling action. That action was removing the material from contact with the blade for a beat or two.
"Welded blades became the norm in about 1980," he continues, "and laborers who use table saws don't have to worry as much about this process of step cutting. They can lay the blade in the cut longer. Still, the table is designed so you bring the material in to the blade and you're able to rock it back and forth. You'll see that a good mason knows that technique, and the laborers will figure out that the blade will cut more efficiently."
What's new and coming?
THINGS CHANGE, even in an industry as old as masonry. New technology won't make a revolutionary change, but there will be some incremental changes in the durability and performance of the tools of the trade.
New motors are being examined for use on brick saws. "I just came back from a meeting with Milwaukee Electric Power