Malco C5R Pipe Crimper: Shape Round Duct Ends for Joining

A plain end on a cut piece of round duct can stop two sections from fitting together. The Malco C5R pipe crimper shapes that end inward, creating the reduced portion that can enter the next section. Its five-blade head does a specific preparation job before the joint is assembled.

A smaller end for the next section

The blades form long, shallow double crimps. Malco lists a crimp length of 1-5/8 inches, or 41.3 mm. That measurement runs along the pipe end; it is not the diameter of pipe the tool accepts. The work happens in successive placements around the rim, rather than by squeezing the entire pipe inside a fixed-size ring.

This is useful when a round sheet-metal section needs an end prepared for an overlapping connection. The application photo shows the jaws at the open edge, with formed grooves extending back from the rim. Before ordering, look at the ends you actually need to join: a section that already has a suitable reduced end may not need this operation.

Malco distinguishes the C5R's longer crimp for round duct from the shorter C4R crimp intended for downspouts. That distinction matters if your shopping list simply says “five-blade crimper.” Match the shape and task, particularly when the job is a rectangular gutter downspout rather than round duct or stove pipe.

The formed end is only one part of the connection. Follow the duct or pipe system's requirements for overlap, fastening and sealing. A crimper does not establish that the assembled installation is airtight or ready for service.

The handles reset between squeezes

The RedLine handles have spring actuation, so they reopen after a squeeze. While working around an end, that return action lets you move to another placement without deliberately pulling the handles apart each time. It is a practical benefit of the mechanism when one pipe end calls for a sequence of hand movements.

The thumb-operated latch keeps the spring-loaded handles together between uses. After working an end, you can close the tool before setting it down, then release the latch when you are ready to use it again.

Malco specifies a 7:1 mechanical advantage for the compound linkage. It remains a hand-powered tool, with the squeeze supplied by you. Think about whether you can comfortably operate that action for the ends on your work list; the leverage figure does not make thick or unsuitable stock acceptable.

The head uses hardened steel with nickel plating. Malco describes the plating as helping resist corrosion. In its general hand-tool care guidance, the company recommends cleaning after use, with a soft cloth as one suitable method, and checking for damage before use. These are useful habits for a tool working among metal dust and offcuts.

The metal sets the limit

For galvanized steel, Malco lists 24 gauge at 0.028 inch (0.71 mm); for mild steel, it lists 24 gauge at 0.024 inch (0.61 mm). Even those two entries carrying the same gauge number have different published thicknesses. Check the material and its actual specification together instead of buying by a “24-gauge” label alone.

Stainless steel has a separate limit: 26 gauge at 0.018 inch (0.46 mm). Aluminum is listed at 0.035 inch (0.89 mm) and copper at 0.023 inch (0.58 mm). Those are workpiece capacities, not a list of metals from which the tool is made. If you cannot identify the stock, establish that before relying on the capacity chart.

If your work includes both galvanized duct and stainless sections, check their separate entries before choosing one crimper for both materials. Being within the galvanized-steel limit does not establish suitability for the stainless piece. Compare the thickness of each material you plan to form, even when the parts have a similar diameter or appear equally sturdy.