Hertel K008385AS Straight Flute Tap 5/16-18 Unc Bottoming

Product Description

The HERTEL K008385AS is a straight flute bottoming tap designed for cutting internal threads in pre-drilled holes where thread engagement must extend close to the bottom of a blind bore. Manufactured from high-speed steel with a bright, uncoated finish, this tap cuts 5/16-18 UNC right-hand threads to a 3B class of fit with an H3 thread limit. The 2-flute straight flute geometry provides chip clearance in through-holes and shallow blind applications. It is a standard-duty tap suited for use by machinists, maintenance technicians, and trade professionals working in metal fabrication, HVAC equipment assembly, and mechanical installation tasks.

This tap is sized for 5/16-18 UNC threads, one of the most common unified coarse thread sizes in trade and industrial applications. It is appropriate for use in ferrous and non-ferrous metals in residential and light commercial maintenance settings. The bottoming chamfer style - with only 1 to 2 threads of lead - allows threading to within a minimal distance of the bottom of a blind hole, making it the correct choice when full thread depth is required near the hole floor. The H3 thread limit supports consistent fit with standard 3B tolerance hardware.

Key Features

• Bottoming chamfer for threading close to the bottom of blind holes
• 5/16-18 UNC thread form with right-hand thread direction
• 3B class of fit with H3 thread limit for standard tolerance hardware
• High-speed steel construction for durability across ferrous and non-ferrous workpieces
• 2-flute straight flute design for chip clearance in shallow applications
• Bright, uncoated finish - no coating buildup concerns in precision thread applications

Compatibility

Designed as a standard OEM-style replacement or new-install tap for use in any application requiring 5/16-18 UNC internal threads cut to a 3B class of fit with a bottoming chamfer profile.

Installation Notes

Installation is performed by qualified machinists or trade professionals using a tap wrench or machine tap holder appropriate for the thread size. Ensure the workpiece is securely fixtured before tapping. Apply a suitable cutting fluid for the base material to reduce tool wear and improve thread finish. For blind holes, use a bottoming tap only after chamfer and plug taps have established the thread form, unless the full hole depth allows direct bottoming entry.