OSG Extension Tap: 1/4"-28 UNF, H3 / 2B-3B, 3 Flute, Bottoming Chamfer

The OSG Extension Tap is used for threading blind holes in hard-to-reach locations, such as deep bores or recessed surfaces in automotive, aerospace, and general machining. Its bottoming chamfer and 3-flute design allow threading close to the bottom of a hole, while the extension provides clearance for obstructions.

This OSG tap has a 1/4"-28 UNF thread size, H3 / 2B-3B tolerance, 3 flutes, and a bottoming chamfer. It is made of high-speed steel (HSS) and is designed for threading blind holes. The manufacturer part number is 1298300, and it is classified as a spiral-flute extension tap.

You can source the OSG Extension Tap MPN 1298300 through 3G Electric, a global industrial equipment distributor. We handle full logistics, customs clearance, and delivery to worldwide destinations. Contact us for availability and lead time; we supply this tap to procurement teams and engineers globally.

Select an OSG extension tap based on thread size (e.g., 1/4"-28 UNF), chamfer type (bottoming for blind holes), flute count (3 for chip evacuation), and material compatibility (HSS for general steel). Ensure the tap's reach and shank length clear the workpiece obstruction. Consult OSG's technical data for optimal speeds and feeds.