Category: Tap: Carbide Insert

What is "Class of Fit" for a Cutting Tap?

10/17/2023

written, compiled and edited by Bernard Martin

What does Class of Fit for a Cutting Tap mean

The basic profile of all UTS threads is the same as that of all ISO metric screw threads. Only the commonly used values for Dmaj and P differ between the two standards.

Class of fit for a cutting tap refers to the specific tolerance or fit that is desired between the threads of the tap and the threads of the hole it is being used to create. In other words, it defines how tightly or loosely the threads should mesh together.

The class of fit is typically expressed using a combination of letters and numbers. The most commonly used standards for class of fit are the Unified Thread Standard (UTS) and the ISO metric thread standard. In the UTS, the class of fit is denoted by a combination of a letter and a number, such as 2B, 3A, etc. In the ISO metric thread standard, it is represented by a combination of a letter and a number, such as 6g, 4h, etc.

For cutting taps, the class of fit is usually specified based on the intended application and the level of precision required. The class of fit can affect factors like the ease of assembly, the strength of the threaded connection, and the ability to engage the threads smoothly during tapping.

A classification system exists for ease of manufacture and interchangeability of fabricated threaded items. Most, but certainly not all, threaded items are made to a UTS classification standard. This system is analogous to the fits used with assembled parts.

Class 1 threads are loose fit, intended for ease of assembly or use in a dirty environment.
Class 2 threads are free fit, and the most common. They are designed to maximize strength considering typical machine shop capability and machine practice.
Class 3 threads are medium fit, still quite common and used for closer tolerances on high quality work.
Class 4 threads previously designated a close fit for even tighter tolerances, but this classification is now obsolete.
Class 5 fit is an interference thread, requiring the use of a wrench for turning. These can be seen in applications like spring shackles on an automobile.

The letter suffix "A" or "B" denotes whether the threads are external or internal, respectively. Classes 1A, 2A, 3A apply to external threads; Classes 1B, 2B, 3B apply to internal threads

Here are some common classes of fit for cutting taps:

Class 2B (UTS) or 6H (ISO metric): This is a standard fit for most general-purpose applications. It provides a balance between ease of assembly and thread engagement.
Class 3B (UTS) or 6HX (ISO metric): This is a tighter fit than Class 2B or 6H and is used when a higher level of thread precision and engagement is required.
Class 2A (UTS) or 6g (ISO metric): This is a loose fit that is often used for applications where ease of assembly and disassembly are important, such as with interchangeable parts.
Class 3A (UTS) or 6HX (ISO metric): This is a tighter fit than Class 2A or 6g and is used in applications where a higher level of precision is required.

The choice of class of fit should be made based on the specific requirements of the project, taking into consideration factors like material type, thread size, intended use, and the desired level of thread engagement. It's important to consult relevant standards and guidelines to ensure that the chosen class of fit is appropriate for the application.

The standard designation for a UTS thread is a number indicating the nominal (major) diameter of the thread, followed by the pitch measured in threads per inch. For diameters smaller than 1⁄4 inch, the diameter is indicated by an integer number defined in the standard; for all other diameters, the inch figure is given.

This number pair is optionally followed by the letters UNC, UNF or UNEF (Unified) if the diameter-pitch combination is from the coarse, fine, or extra fineseries, and may also be followed by a tolerance class.
Example: #6-32 UNC 2B (major diameter: 0.1380 inch, pitch: 32 tpi)

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Browne & Co Appointed as Representatives of Regal Cutting Tools: Focus on Tapping and Threading Products

4/1/2022

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Browne & Co has been appointed as Regaional Managers for Regal Cutting Tools. They will be responsibilve for distributor and technical support for the Kentucky, Ohio, and Western Pennsylvania market areas.

Regal Cutting Tools has been manufacturing world-class cutting tools since 1955 Regal offers a high performance SuperTuf series of taps for the demanding difficult to machine materials.

Regal also manufactures special taps from blanks with as little as 24 hour notice.

Regal Cutting Tools
They manufacture tapping and thread milling tools in a wide variety of materials, coatings, and treatments to accomplish your individual needs and demanding job requirement.

Regal and their highly respected distributors share a common goal: To achieve cost effective tooling solutions through improved tool life, technical support, coatings, and effective inventory management systems that accomplish uptime goals.

According to Dave Browne, President of Browne & Co, "Regal Cutting Tools. is a well established and trusted brand within the metalcutting industry. Their full line of taps as well as their tap specials capabilities really compliment our product mix and fills an area we have pretty deep experience in but didn't have a product to recommend. We're really looking forward to working with our customers and running these tools!"

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The Different Types of Carbide Taps and When to Use Them

8/18/2021

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This is Part 2 of our series on Carbide taps. Be sure to check out Part 1 if you missed it:
Carbide Taps: A Practical User’s Guide to When, What, How and Why

Carbide taps have a lot of advantages, especially when you’re cutting very abrasive materials. The absolute best choice for tapping glass-filled polycarbonates, space age alloys, nonferrous materials, cast iron, and a range of other exotic materials, their anti-friction qualities lead to a longer tool life.

Because of this, you’ll require fewer replacements, less downtime, and increased productivity.

The durability, flexibility, and longevity of carbide taps is unparalleled, allowing you – and your employees – to focus on what’s important: getting the job done.

Regal Cutting Tools offers an unparalleled selection of taps for many applications, allowing you to source all of your essential taps from one supplier.

In today’s post, we’re going to take a closer look at a few of the options that they offer.

Carbide Taps Allen Benjamin North American GW Schultz GWS TOol Tapping

Standard Screw Thread Insert Taps

S.T.I. (Screw Thread Insert) Taps are special taps for helical coil wire screw thread inserts, which provide positive means for protecting and strengthening tapped threads in any material.

Typically used on softer abrasive materials, these taps create more accurate thread forms than other standard taps. When you need to be precise, these carbide taps are the best choice.

STI taps are correctly sized to produce an internal thread that accommodates a helical coil wire screw thread insert. The insert, in turn, will accept a screw thread of the nominal size and pitch at final assembly. Screw thread inserts provide stronger tapped threads (stronger assemblies) due to a more balanced distribution of loads throughout the length of thread engagement.

Thread Forming Tap

Roll Taps (aka, Thread forming taps, Form taps0 offer improved thread quality and strength due to the fluteless design, and therefore allows for greater fastener strength in the threaded product. This tap does not cut, so it is “chipless,” and therefore will not cause a chip problem. This is why thread forming, over thread cutting, eliminates costly and time-consuming chip clean-up and disposal.

Thread forming taps are fluteless and include lubrication grooves. Not intended for general applications, they work by displacing the metal without removing it. Because of this, they are ideal for chip removal in blind holes.

Roll Thread Forming Taps Features

Improved thread quality and strength due to fluteless design of tap; allows greater fastener strength in threaded product.
Tapping speeds can be increased as much as double that of conventional cutting taps…more tapped holes per hour.
Thread forming (over thread cutting) eliminates costly and time-consuming chip clean-up and disposal.
Improved tap life, even in abrasive materials…no cutting edges to get dull.
Lubrication grooves allow forced passage of air and lubricant when tapping.
Simplifies tapping of problematic blind bottoming holes where adequate chip clearance is impossible with chip-producing cutting taps.

Carbide Insert Taps

A cost-efficient solution, only the cutting portion of insert taps is made from carbide. Their HSS body is able to absorb vibration and account for their lack of rigidity.

If you’re considering testing the waters with carbide taps, insert taps are a great option. It's a very economical way to utilize the benefits of carbide with solid carbide cutting face inserts meticulously brazed to a H.S.S. tap body.

Carbide Insert Tap Features

High speed steel body absorbs excessive shock and offers the rigidity necessary to minimize carbide breakage or chipping.
Ideal for high production runs, offering the capability to achieve higher speeds and feeds, with fewer tool changes.
High performance tapping allows greater efficiencies in part throughput.
Can also be used in conjunction with surface treatments for enhanced performance.
Carb-I-Sert® Taps are available in a wide range of sizes (inch and metric) in both straight and taper pipe threads.

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What is "Class of Fit" for a Cutting Tap?

Browne & Co Appointed as Representatives of Regal Cutting Tools: Focus on Tapping and Threading Products

The Different Types of Carbide Taps and When to Use Them

Standard Screw Thread Insert Taps

Thread Forming Tap

Carbide Insert Taps

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