JAPAN SKC HAND TAPES - No:803 UNF

More info

Japan SKC No. 803 hand taps are high-quality threading tools made from carbon steel (SKS). The "803" series specifically refers to their standard sets of hand taps, which are widely recognized in machine shops for their reliability in manual threading applications.

The 3-Piece Set Configuration

A standard SKC 803 UNF set includes three distinct taps designed to be used in sequence:

Taper Tap: Features 8 to 10 chamfered threads. It is used to start the thread easily, especially in rough materials.
Plug Tap: Features 3 to 5 chamfered threads. This is the most common tap for general use when you don't need to thread all the way to the very bottom of a hole.
Bottoming Tap: Features only 1.5 chamfered threads. It is used after the Taper or Plug tap to cut threads as deep as possible into a blind hole.

Common UNF Sizes & Specifications

The UNF (Unified Fine) series is used when higher tensile strength is required or for applications in thin-walled tubes. Below are the common sizes available in the SKC 803 UNF range:

Size (Inches)	Threads Per Inch (TPI)	Tap Drill Size (Approx.)
1/4"	28	5.50 mm
5/16"	24	6.90 mm
3/8"	24	8.50 mm
7/16"	20	9.90 mm
1/2"	20	11.50 mm
5/8"	18	14.50 mm
3/4"	16	17.50 mm
1"	12	23.25 mm

Key Features

Material: Made from Alloy Tool Steel (SKS2), providing a good balance of hardness and toughness for hand tapping.
Origin: Genuine SKC tools are manufactured by SKC Thread Tool Mfg. Co., Ltd. in Japan.
Application: Ideal for cleaning existing threads or cutting new threads in mild steel, brass, and aluminum.

[!TIP]

Always use a high-quality tapping oil or lubricant when using carbon steel taps to prevent the teeth from overheating and to ensure a smooth finish.