Greenlee 3-1/2 Inch Conduit Manual Knockout Set

Description

Struggling to cut large 3-1/2-inch conduit holes with hole saws that chatter and leave jagged metal burrs on switchgear boxes? The Greenlee 3-1/2 Inch Knockout Set punches round holes in ten-gauge mild steel without metal distortion. It operates via manual wrench drive or hydraulic rams, requiring a 1-1/8-inch pilot hole before staging.

Precision-machined high-carbon tool steel constructs the heavy punch, die cup, and drive screw, heat-treated to 60 HRC hardness. The passive mechanical punch draws zero electrical power on its own, developing thirty tons of mechanical punch tonnage when turned with a ratchet wrench. Total dry set weight measures 11 lbs. Punch diameter measures four inches across to match standard 3-1/2-inch trade conduit outside dimensions.

Key Features of Greenlee K3BB-3-1-2

Commercial electricians buy Greenlee K3BB-3-1-2 knockout sets to punch large service entrance conduit holes through heavy electrical panel cabinets. Equipment pricing delivers precision tool steel dies that punch burr-free holes without flying metal shavings or arbor chatter.

• Precision-ground four-point punch profiles split metal slugs into pieces for fast drop-out from die cups.
• Hardened high-carbon tool steel dies punch through ten-gauge mild steel and twelve-gauge stainless steel.
• Heavy 1-1/8-inch ball-bearing drive screws reduce manual wrench torque by fifty percent during hand punching.
• Laser-etched crosshairs on die cups align with center punch layout lines for accurate hole positioning.
• Threaded draw studs adapt to standard Greenlee hydraulic hand pumps and battery-powered knockout rams.
• Clean round punch edges eliminate hand filing and de-burring before installing conduit connectors.
• Black oxide surface finishes resist jobsite corrosion, rust, and metal-on-metal thread galling.

Punch Tonnage Draw Stud Metrics

Mechanical bench testing confirms the 1-1/8-inch ball-bearing drive screw withstanding thirty tons of axial draw force without thread deformation. When punching ten-gauge mild carbon steel, manual ratchet torque peaks at 180 foot-pounds to shear the metal slug. The four-point punch face splits the slug in half, dropping pieces from the die cup without pry bars. Hole roundness tests measure within 0.003 inches of true four-inch diameter, producing clean burr-free margins that seat conduit locknuts flat.

Switchgear Punching Realities Maintenance

Tightening this 11 lb punch set takes two hands on a long ratchet wrench or breaker bar, bracing the panel box against wrench torque. Applying thread lubricant to the drive screw ensures smooth rotation under heavy tension. Do not buy this manual set for un-drilled panels without pilot holes, hardened armor plate, or stainless steel over ten-gauge.

• Coat drive screw threads with high-pressure anti-seize lubricant before every large hole punch.
• Wipe metal swarf and cutting oil off the punch cutting edges after each deployment.
• Inspect the die cup rim for chipping or metal rollout after punching stainless steel.

Factory Warranty Manifest Inclusions

Greenlee covers this manual knockout set with a Lifetime manufacturer warranty against material defects and punch cracking. The factory packaging contains the 3-1/2-inch conduit punch, matching die cup, 1-1/8-inch ball-bearing drive screw, and an illustrated commercial electrical punching guide.