Value Collection MSC-04919429 Hand Tap 1-1/4-7 Unc Lh

Product Description

The VALUE COLLECTION MSC-04919429 is a 1-1/4-7 UNC left-hand straight-flute hand tap manufactured from high speed steel with a bright uncoated finish. Designed for cutting internal left-hand threads in through-holes and blind holes, this tap uses a taper chamfer to gradually engage the workpiece and distribute cutting load across the leading threads. The 4-flute geometry provides adequate chip clearance in typical threading applications. With a Class 3B fit and H4 thread limit, it produces close-tolerance threads suited to assemblies requiring a snug, controlled thread engagement. Machinists, tool-and-die makers, and maintenance technicians install this tap in standard hand-tapping operations or low-speed machine tapping setups.

This tap is sized for 1-1/4-7 UNC thread form — a coarse-pitch unified national thread common in heavy structural fastening, large-bore hydraulic fittings, and industrial machinery frames. The left-hand thread direction makes it appropriate for applications where standard right-hand threads would loosen under operational rotation, such as certain spindle assemblies, counterrotating shafts, and specialized fastener installations. The taper chamfer (approximately 8 to 10 threads of lead) makes starting the thread easier and is well suited to through-hole work. This is a single-tap-per-package item intended for professional shop and field use.

Key Features

• 1-1/4-7 UNC coarse-pitch thread form for heavy industrial and structural applications
• Left-hand thread direction for counterrotation and specialty fastener applications
• Taper chamfer distributes cutting load for easier thread starting, especially in through-holes
• High speed steel construction withstands the heat and stress of hand and low-speed machine tapping
• Bright uncoated finish — no coating buildup to affect thread tolerance
• Class 3B fit with H4 thread limit for close-tolerance, controlled thread engagement
• 4-flute straight-flute design provides chip clearance and stability during the cut

Compatibility

Designed as an OEM-style replacement or direct-use tap for any application requiring a 1-1/4-7 UNC Class 3B left-hand internal thread in steel, cast iron, aluminum, or similar machinable materials.

Installation Notes

Machinist or tool-and-die trade experience is recommended for large-diameter hand tapping operations at this thread size. Secure the workpiece firmly before tapping, apply appropriate cutting fluid for the workpiece material, and advance the tap gradually with back-off strokes to break chips and prevent binding. Do not apply excessive torque — large-diameter taps are susceptible to breakage if forced. Refer to shop standards or applicable ASME B1.1 thread specifications when tolerance verification is required.