The rings on a hand tap indicate which tap it is in a hand tap set. Such sets usually consist of two or three matched taps used in sequence to cut an internal thread in multiple steps. This is particularly important for harder materials or when high thread accuracy is required.

Hand taps are used manually and differ from machine taps, which typically cut the thread in a single operation.

A complete hand tap set consists of:

• Taper Tap (First Cut)
  Marking: 1 ring
  Function: Starts the thread and cuts about 50–60% of the final depth
  Advantage: Easier to start, reduces mechanical load at the beginning

• Intermediate Tap (Second Cut)
  Marking: 2 rings
  Function: Deepens the thread to about 70–80%
  Advantage: Keeps the tool stable and prepares for the final cut

• Finishing Tap (Third Cut)
  Marking: No rings
  Function: Cuts the thread to final size
  Advantage: Ensures final shape and precise fit of the thread

These markings help ensure the correct sequence and proper thread formation. Hand taps with rings do not cut a complete thread.

The difference lies mainly in design, application, and durability:

Hand Tap:

• Used manually with a tap wrench

• Usually comes in a set of 2 or 3 (taper, intermediate, finishing tap)

• Has a long lead-in for easier manual use

• Ideal for slow, precise manual work, e.g., in a workshop

Machine Tap:

• Mounted in drill presses, lathes, or CNC machines

• Always a single tap, with special lead-ins and flutes (e.g., spiral flutes)

• Cuts the thread in one operation

• Designed for higher cutting speeds and larger quantities

• Fast, efficient, and reliable, especially in mass production

Summary:

• Hand Tap: For manual, step-by-step thread cutting

• Machine Tap: For automated, high-speed cutting with machines

Machine taps are used when threads need to be produced quickly, efficiently, and precisely – especially in industrial or high-volume production.

Typical applications:

• CNC machining or lathe/milling operations with automated threading

• Production settings where time and consistency are critical

• Deep or blind holes requiring chip evacuation via the flutes

• Hard or tough materials needing optimized tap geometry

Advantages:

• Time-saving: thread cut in a single pass

• High repeatability

• Better chip removal depending on flute design (e.g., spiral for blind holes)

• Longer tool life with proper use

• Higher durability

A die is used to cut external threads – for example, on rods, shafts, or bolts. It is the counterpart to a tap, which is used for internal threads.

Application:

• The die is mounted in a die holder

• Then it's placed on the workpiece and rotated clockwise to cut the external thread

• Cutting oil reduces friction and extends tool life

Common uses:

• Creating or re-cutting threads on shafts, bolts, or threaded rods

• Repairing damaged external threads

• Small-batch or custom fabrication in workshops

Summary:
A die is used to precisely cut or restore external threads – manually or by machine, depending on the type.

A die holder is a tool used to clamp and guide a threading die. It is used to manually cut an external thread – e.g., on a shaft or round rod.

Structure and function:

• Consists of a handle with a central clamping mechanism

• The die is inserted into a circular opening and secured with screws

• Turning the holder drives the die evenly onto the workpiece to cut the thread

Typical features:

• Handles ensure optimal torque for manual turning

• Available in various sizes to fit different die diameters and thicknesses

Applications:
Used mainly in trades, maintenance, or custom fabrication – wherever external threads are cut manually.

What is a die used for?

A die is used to cut external threads – for example, on rods, shafts, or bolts. It is the counterpart to a tap, which is used for internal threads.

Application:

• The die is mounted in a die holder

• Then it's placed on the workpiece and rotated clockwise to cut the external thread

• Cutting oil reduces friction and extends tool life

Common uses:

• Creating or re-cutting threads on shafts, bolts, or threaded rods

• Repairing damaged external threads

• Small-batch or custom fabrication in workshops

Summary:
A die is used to precisely cut or restore external threads – manually or by machine, depending on the type.

For threading stainless steel, a high-quality die made from HSS-E (high-performance high-speed steel with at least 5% cobalt, also marked as HSS-Co) should be used.

Why?
Stainless steel is tough, hard, and prone to work hardening. Standard HSS dies wear quickly or may break.

Recommended die for stainless steel:

• Material: HSS-E or HSS-Co (min. 5% cobalt)

• Surface treatment (optional): Vaporized finish for longer tool life – improves coolant adhesion and reduces cold welding (our VX series)

• Geometry: Special cutting angles and optimized cutting edges for tough materials

Tips:

• Always use cutting oil or coolant to reduce friction and extend tool life

• Apply consistent, moderate pressure

• For heavy-duty or production use, consider machine-driven tools

Conclusion:
Using an HSS-E die for stainless steel significantly increases tool life, as it's better suited for the material's hardness and toughness.

Here is an overview of the most common thread types used in mechanical, pipeline, and other technical applications:

Metric Thread (ISO metric):

·       Coarse (M): e.g., M10 x 1.5 (10 mm diameter, 1.5 mm pitch)

·       Fine (MF): smaller pitch, e.g., M10 x 1.0 or M10 x 0.75

·       Widely used in Europe and globally, standardized to ISO 68/261

NPT (National Pipe Thread):

·       American tapered pipe thread for pressure-tight sealing

·       Common for gas and water pipes, e.g., 1/2" NPT

NPS (National Pipe Straight):

·       Standard: ANSI/ASME B1.20.1

·       Straight pipe thread (not tapered like NPT)

·       Used for mechanical connections (not pressure-tight)

·       Inch sizes, e.g., 1/2" NPS

BSPT (British Standard Pipe Taper):

·       Standard: ISO 7-1 / BS 21

·       Tapered thread for pressure-tight fittings

·       Inch sizes, e.g., 1/2" BSPT (not interchangeable with NPT!)

·       55° flank angle vs. 60° (NPT)

G Thread (BSP – British Standard Pipe):

·       Cylindrical pipe thread

·       Example: G 1/2", often used for water connections and fittings

UNC, UNF, UNEF (Unified Thread Standard):

·       UNC: Coarse, UNF: Fine, UNEF: Extra fine

·       Used in USA/Canada, per ANSI/ASME B1.1

Trapezoidal Thread (Tr):

·       Used for power/motion transmission, e.g., spindles

·       High load capacity, e.g., Tr 16 x 4

Whitworth Thread (BSW, BSF):

·       Historical British standard

·       BSW: Coarse; BSF: Fine

Buttress Thread:

·       Asymmetrical profile for high axial loads in one direction

·       Used in presses, clamping devices

Round Thread:

·       Ideal for harsh environments (e.g., brake spindles, couplings)

·       Easy maintenance and cleaning

·       High load capacity – up to thousands of tons

Choosing the right drill size is crucial for a precise and durable thread. For metric ISO threads, use the formula:

Drill Diameter = Thread Diameter – Pitch
(Valid for metric threads only)

Example: For M8 with 1.25 mm pitch → 6.75 mm drill

Overview: Drill sizes for ISO metric coarse threads:

Notes:

• Values are for standard ISO coarse threads
• Fine threads require larger drill sizes
• For inch or special threads, use appropriate drill charts