Above: With its push-pull motion, a reciprocating saw blade cuts through metal quickly and cleanly without generating hot spark projectiles

Reciprocating saw blades offer advantages in tube and pipe cutoff operations

Fabricators are familiar with removing portions of tube and pipe using abrasive wheels, but the benefits of performing the same process with a reciprocating saw provide a clear advantage, according to Jay K. Gordon, North American sales manager for saws and hand tools at The L.S. Starrett Co. in Athol, Massachusetts.

The advantages of a reciprocating saw over an abrasive wheel for cutoff operations begins with operator safety. “In our view, the reciprocating saw is much safer because of the operation itself and the fact that it is pulling chips as opposed to melting through the material.”

Gordon explains that a reciprocating saw blade moves backward and forward. The blades are designed specifically for a reciprocating saw and can’t be used with any other type of hand or power tool.

HOLD THE HOT

With its push-pull motion, a reciprocating blade can cut through metal quickly and cleanly without generating hot spark projectiles that can cause operator injury and property damage via fire or explosion of flammable materials, Gordon says. “The blades are engaged for a relatively short time in a very quick fashion. That eliminates the heat or any type of sparking that would normally happen in an abrasive-type application.”

      In addition to tube and pipe, a reciprocating saw is suitable for cutting solid workpieces.

The approximate 1,800° F sparks produced by an abrasive cutoff wheel are considered chips, but may be sent 30 to 40 ft . from the grinder, whereas the chips from a reciprocating saw are larger and are safely deposited on the shop floor beneath the saw, Gordon says. “The bigger the chips, the safer the operation because they are not flying all over,” which also makes cleanup easier. Larger chips don’t become metallic dust like sparks from an abrasive saw that create a greater likelihood of being inhaled, he adds. Wearing a face mask can minimize, but not eliminate the risk. The fine grit from an abrasive wheel can be a challenge to remove from surfaces. Gordon recommends wearing safety equipment, such as gloves and goggles, when operating a reciprocating saw. Hearing protection is another safety equipment option for operators, but reciprocating saws are 15dB quieter on average than an abrasive wheel, Gordon says.

SIZE MATTERS

An operator’s physicality can influence results. Larger, stronger operators tend to exert more pressure on a saw, which in turn generates more noise, heat, torque and larger chips.

The workpiece material also plays a significant role. “If you are cutting aluminum, you are not likely to generate as much heat as if, say, you’re cutt ing stainless steel because you have to push harder to get through it.” The workpiece material along with the size of the teeth on the saw will also impact chip size. For example, sawing aluminum with a four-tooth blade produces a larger chip than sawing steel with an 18-tooth blade, Gordon explains. “The chips are formed by the teeth and the gullet, so if you have a small tooth and small gullet, you will have relatively small chips.”

A problem arises when chips are larger than the gullet or teeth, he notes, because those chips load the teeth, resulting in tooth strippage and shorter tool life. In addition, an operator experiences less vibration when operating a reciprocating saw compared to a grinder with an abrasive wheel, which aids worker retention, according to Gordon. “It doesn’t reduce vibration 100 percent, but it is more comfortable for operators to hold as they move through the material.”

Another difference between a reciprocating saw and an abrasive wheel is the amount of reach each tool offers. Because there are no guards on a reciprocating saw, Gordon says its blade can reach a significant distance from the end of the saw and access tight areas precisely. “You have options from about 4 in. to 12 in. on a reciprocating saw, which gives you a lot better reach.”

Guards are required on a grinder, and if ignored and misused, users are subject to significant fines. Nonetheless, an operator might be tempted to remove the guard to reach a particular area. However, it only takes a fraction of a second for a wheel to break and the results can be catastrophic to the operator and other workers nearby. In addition, reciprocating saws are lighter than the abrasive option and reduce changeover for substrate geometry differences. For example, a 9 in. grinder is needed to cut a 3 in. pipe, but the saw size remains the same no matter the blade length and the user can make the cut with a 6 in. blade. The blades hold a constant size and, therefore, a constant surface footage, so the cutting efficiency is similar from the first to the last cuts made, Gordon says. “That allows the teeth and the blade to engage properly and allows the chip to form as best it can, depending on the material. It allows the chip to clear out, which increases blade life, accuracy and the smoothness of the cut.”

CASTING SHADE

Gordon notes that Starrett makes a variety of reciprocating blades to suit specific applications but generally, two different blade shapes are available: parallel for harder cuts, especially when the tip needs to be forced, and tapered for straighter cuts, which also offers a better possibility for getting into hard-to-reach places.

While a blade with a yellow-colored shank is made of carbon steel, Gordon says Starrett’s 3X Power reciprocating blades are bi-metal blades that have a harder tip combined with a somewhat flexible back to extend tool life. The bi-metal blades will endure a tremendous amount of torsion and are still used effectively with limited risk of breakage.

“Compared to a carbon reciprocating blade, a bi-metal blade outlasts it two to two and a half times, at least, given the same parameters.”

When it comes to the bottom line, Gordon says company tests show that the cost of operating a reciprocating saw is about a third the cost of using an abrasive wheel. “We conducted real-world tests, and the cuts were timed and measured, and blade life was measured by the number of cuts.”

In one set of performance cutting tests conducted at Starrett that compared 6 in. 3X Power reciprocating blades to 4.5-in.-diameter abrasive cutoff wheels, the company reported that the reciprocating blades yielded an average annual savings of more than $14,000 when making 74,750 cuts in Schedule 40 steel pipe. This example is based on the work that a small or mid-sized fabricator may see and assumes three operators at the national average labor rate using one box of abrasives with 25 wheels in a box per week each, for a total of 75 wheels weekly versus six reciprocating blades per operator each week for a total of 18 blades for the same weekly time period. “In addition,” Gordon claims, “you are getting a much better cut. FFJ