Value Collection JY4848198 Straight Flute Tap 7/8-20 Unef Hss

Product Description

The VALUE COLLECTION JY4848198 is a straight flute tap designed for cutting 7/8-20 UNEF (Unified Extra Fine) internal threads in ferrous and non-ferrous materials. Built from high-speed steel (HSS) with a bright, uncoated finish, this tap delivers consistent thread form across production and maintenance applications. The plug chamfer — typically 3 to 5 threads of lead — makes it suited for through-hole threading where the tap can pass fully through the workpiece. With 4 flutes and an H4 thread limit, it holds a 3B class of fit tolerance, which is the standard for general-purpose threaded assemblies requiring controlled clearance.

This tap is used in machine shop, toolroom, and maintenance environments where extra-fine pitch threading is required on larger-diameter fastener holes. The 7/8-20 UNEF designation is common in aerospace, automotive, and precision mechanical assemblies where fine thread engagement and vibration resistance are priorities. It is compatible with tapping heads, CNC lathes, drill presses, and manual tap handles. Right-hand threading matches standard fastener orientation. The 4-11/16 inch overall length accommodates standard tapping chucks and extension holders.

Key Features

• 7/8-20 UNEF thread form with H4 thread limit for controlled 3B class of fit tolerance
• Plug chamfer (3-5 lead threads) optimized for through-hole tapping applications
• High-speed steel construction provides hardness and wear resistance across a broad range of workpiece materials
• 4-flute design improves chip clearance and thread finish stability during the cut
• Bright/uncoated finish suitable for use with standard tapping fluids and cutting oils
• Right-hand thread direction matches standard fastener orientation

Compatibility

Designed for use in through-hole tapping operations requiring a 7/8-20 UNEF thread form and 3B class of fit. Compatible with standard tapping chucks, tapping heads, and manual tap wrenches sized for the tap shank.

Installation Notes

Installation should be performed by a qualified machinist or toolroom technician. Ensure the workpiece is securely fixtured and the tap is aligned perpendicular to the hole before engagement. Apply appropriate cutting fluid or tapping oil throughout the operation to extend tool life and improve thread finish. Back off periodically to break chips and prevent tap breakage in deep or interrupted cuts.