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OSG Extension Tap: 3/8"-16 UNC, H3 / 2B-3B, 4 Flute, Plug Chamfer - Pulley Taps
OSGPulley Taps

OSG Extension Tap: 3/8"-16 UNC, H3 / 2B-3B, 4 Flute, Plug Chamfer

The OSG Extension Tap (MPN 1290801) is a 3/8"-16 UNC pulley tap with a H3 / 2B-3B tolerance, 4-flute design, plug chamfer, and black oxide high-speed steel construction. This tool is engineered for threading…

SKU 3G-OTH-308197

Brand
OSG
Item
Extension Tap: 3/8"-16 UNC, H3 / 2B-3B, 4 Flute, Plug Chamfer
Category
Pulley Taps
Available to Order
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Local availability & support — Singapore

Local office
20 Woodlands Link #09-05, Singapore 738733
Phone
+65 8878 8355
Delivery
Same-day or next-business-day delivery within Singapore for in-stock items; 7–14 days for factory-order parts from Europe.
Payment
Invoicing in SGD. PayNow, bank transfer, and corporate PO accepted.
Ships to
Singapore

Technical Specifications

OSG
Manufacturer Part Number
1290801
Type
H3 / 2B-3B, Plug Chamfer, Black Oxide High Speed Steel
Flute
4

Technical Documents

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OSG Products
3G Electric (S) Pte. Ltd. — Singapore

Product Description

The OSG Extension Tap (MPN 1290801) is a 3/8"-16 UNC pulley tap with a H3 / 2B-3B tolerance, 4-flute design, plug chamfer, and black oxide high-speed steel construction. This tool is engineered for threading applications requiring extended reach, with its H3 / 2B-3B classification ensuring precise fit for class 2B-3B threads.

Frequently Asked Questions

What is an OSG extension tap used for?

An OSG extension tap is used to cut internal threads in hard-to-reach or deep-hole applications, such as pulley hubs or engine blocks. The extended shank allows threading where standard taps cannot reach, making it essential for maintenance and production in automotive, aerospace, and general machining.

What are the specifications of the OSG extension tap 3/8"-16 UNC?

This OSG extension tap has a 3/8"-16 UNC thread, H3 / 2B-3B tolerance, 4 flutes, plug chamfer, and is made from black oxide high-speed steel. The MPN is 1290801. It is designed for threading through holes and blind holes in ferrous materials up to 24 HRC.

Where to buy OSG extension taps worldwide?

3G Electric supplies OSG extension taps worldwide, handling full logistics and customs clearance. As a global industrial solutions provider, we source genuine OSG cutting tools like the 3/8"-16 UNC tap (MPN 1290801) and deliver to any international destination. Contact us for pricing and lead time.

How to select the correct OSG extension tap for a job?

Select an OSG extension tap based on thread size (e.g., 3/8"-16 UNC), material hardness, and hole depth. For blind holes, use a plug chamfer; for through holes, a bottoming chamfer. Match the H limit (e.g., H3) to your required thread class (2B or 3B). Always verify shank length clears the workpiece.

Used in

Common applications for OSG
Automotive engine block production — OSG micro drill bits for oil gallery and coolant passage drilling in cast iron
Medical device manufacturing — OSG micro drill bits for drilling bone screw pilot holes in stainless steel implants
Aerospace component machining — OSG micro drill bits for fastener holes in titanium alloy structural parts
Mold and die making — OSG micro drill bits for cooling channel drilling in hardened tool steel (HRC 45-50)
Electronics enclosure fabrication — OSG micro drill bits for precision holes in aluminum alloy housings (with appropriate coating selection)
General engineering job shops — OSG micro drill bits for small-diameter hole drilling in mild steel and alloy steel parts

OSG Products

3G Electric supplies OSG pulley taps. We supply genuine products with in-stock availability on common SKUs, technical documentation, commissioning support, and warranty service — worldwide.

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OSG Extension Tap: 7/16"-14 UNC, H3 / 2B-3B, 4 Flute, Plug Chamfer, Black Oxide High Speed Steel (MPN 1291401)
OSG Extension Tap: 7/16"-14 UNC, H3 / 2B-3B, 4 Flute, Plug Chamfer, Black Oxide High Speed Steel (MPN 1291601)
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OSG Extension Tap: 7/16"-14 UNC, H3 / 2B-3B, 4 Flute, Plug Chamfer, Black Oxide High Speed Steel (MPN 1291601)

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