Cutting Metal On-Site

by Jonathan McGaha | 31 March 2016 12:00 am

“Usually the most popular reason to cut metal is the need to adjust it to the right size for a particular application,” says Andrew Plowman, director of product management, Milwaukee Tool, Brookfield, Wis. “Other reasons to cut include shaving a surface down or controlling a surface a bit more for a better fit.”

In the shop, most metal cutting is done with heavy-duty, stationary air, electric or hydraulic machinery with larger pieces of metal and major cuts for forming and fabrication. Cuts can be made repetitively with stop blocks, guides and jigs.

But on a job site, most metal cutting is done with air, electric or hydraulic handheld portable tools. “On-site, equipment is usually limited to handheld tools that can easily be transported and set up for the cutting needed,” says Simon Wainwright, product manager, CS Unitec Inc., Norwalk, Conn. “In the field, most cuts are custom lengths and are one-offs, and there are space limitations. Cutting is most often accomplished in difficult working conditions and often times, unpredictable weather conditions.”

What follows are tools and tips on how to correctly cut metal on-site.

Tin Snips

One of the most reliable and commonly used tools to cut light-gauge sheet metal and roof flashing on-site is tin snips or manual hand shears. These tools usually produce clean, straight or curved cuts, and will usually not destroy the galvanic layer of the metal. During cutting, metal’s galvanized zinc coating must not be scratched or damaged. This could cause premature rusting at the cut ridge.

When installing metal on-site, minor adjustments must be made by trimming. Often, pre-fabricated pieces can be sent to a job site that may not fit exactly as measured. A job-site worker can use tin snips to trim metal to the correct size and hem metal edges for wrapping adjacent pieces. “Trimming is done for a clean, finished cut,” says Kristin Herald, inside sales, Tenryu America Inc., Hebron, Ky. “Metal requires finish-edge quality and accuracy.” Wainwright agrees, saying, “Perhaps a 1/8-inch must be shaved off a metal railing to make it fit into a space, or an angle of a cut must be adjusted to fit the final installation.”

Offset compound snips are offset below the handle to keep your cutting hand above the work, and the compound action allows you to cut thicker material with less effort. Compound snips, also called aviation snips, are color coded. Green snips cut clockwise curves; red snips cut counterclockwise curves.

Niblers

A nibbler type electric tool is extremely versatile and curve-compatible, particularly suited for trapezoid sheet metal, corrugated sheet metal, profiles and curved single-rolled sheets. These small-mouthed power scissors permit faster metal cutting with less manual effort. Nibblers may be manual (hand operated) or powered. Power nibblers are often powered by compressed air, though electrical types also exist.

One nibbler type operates much like a punch and die, with a blade that moves in a linear fashion against a fixed die, removing small bits of metal and leaving a kerf approximately 6 mm wide. Another type operates similar to tin snips, but shears the sheet along two parallel tracks 3- to 6-mm apart, rolling up the waste in a tight spiral as it cuts.

Circular Saws

A circular saw is a frequently used tool for cutting metal on job sites. With it, material can be cut in place, such as a long run for a soffit that needs trimming or bundled in bulk. With today’s advanced saws and safety features, the cutting is clean and burr free, producing more scorchfree edges that don’t require post-cut finishing. Fewer sparks are generated when carbide tips are used because they cut through, instead of grind away the metal. This is important in a confined job-site environment where showers of hot metal chips and sparks can be a safety hazard. Wainwright stresses that when cutting metal on busy job sites, workers must position themselves so as not to spray sparks or metal chips at others, or cause damage to other materials in the area.

Grinders

A commonly used metal-cutting tool on job sites is the metal grinder. It’s a hand-operated tool that spins an attached cutting disc or wheel at a fast rate of speed to cut metal quickly. Abrasive cutting wheels come in various sizes and thicknesses. Some wheels cut faster than others. The wheel’s abrasive material influences the cut rate and its life span. Use the cutting wheel at surface. Apply the correct amount of pressure to allow the cutting wheel to do the work.

Bandsaws

The bandsaw is especially popular due to the clean and consistent cuts it makes, as well as its ease on the user. “The downward momentum of the tool does almost all of the work for the user,” Plowman says. “If a user is looking to make a quick cut that is harder to reach, they might try a Sawzall with a metal-cutting sawblade. The additional benefit of the Sawzall is the utility it provides on-site. Users can go from cutting metal to sawing wood in just a matter of moments.”

At the Job Site

At job sites, cordless metal-cutting tools provide portability and great utility due to the limited supply of power sources. Because of advancements in lithium-ion, electronics and motors, cordless tools are meeting and surpassing the performance of their corded predecessors. “These cordless options also eliminate the hassle of maneuvering around cords and gives users the freedom to be more productive,” Plowman says.

Wainwright stresses that the job site is not a controlled environment. “It is not uncommon for equipment to be stolen,” he says. “Equipment used in the field needs to be portable and easily setup and broken down so it can be stowed in the back of trucks or in locked permanent trailers at the end of the day. Safety concerns are different in the field than in the shop because job sites are not a controlled, familiar and consistent environment. Job sites are busy places and caution must be employed when making cuts when others are in the area.”

Source URL: https://www.metalconstructionnews.com/articles/cutting-metal-on-site/

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