Cutting round ductwork requires precision and the right tools. A duct cutter, specifically designed for circular ducts, is ideal. First, mark the cutting line on the duct using a measuring tape and pencil. Then, position the duct cutter's blade on the marked line. Apply steady pressure, rotating the cutter around the duct. The sharp blade creates a clean, precise cut. Alternatively, a reciprocating saw with a metal-cutting blade can be used for larger round ducts. Ensure the duct is securely held in place while making the cut to prevent slips and maintain accuracy.

Welders use a variety of methods in their trade. Different types of welding are better suited for different purposes and contexts. For example, stick welding is a versatile form suitable for most metals and alloys. The most common types of welding include:

• Stick welding: $100–$1,000

• Metal Inert Gas (MIG) welding: $250 and up

• Tungsten Inert Gas (TIG) welding: $250 and up

• Gas welding: $150 and up

• Forge welding: $15–$25 per hour

Yes, you can use a saw to cut metal pipes. The best saw to use is a reciprocating saw, but even a fine-tooth hacksaw can get the job done. No matter which saw you use to cut metal pipes, wear protective gear, like work gloves, safety goggles, and ear plugs. Apply a firm, steady pressure to the tool, and always ensure the pipes are secured so they don't move while you make the cuts.

Cutting rectangular ductwork requires careful measurements and the right technique. Use a measuring tape and pencil to mark the cutting lines accurately. Tin snips are excellent for straight cuts on smaller ducts. For more extensive or thicker rectangular ducts, a reciprocating saw with a metal-cutting blade is effective. 

Ensure the duct is well-supported and secure while cutting to prevent wobbling and maintain precision. After cutting, use a metal file to smooth any sharp edges, ensuring safety during installation.