Cutting threads: Everything you need to know

Thread cutting is a fundamental machining process that creates threads by removing material with precision. While widely employed in industries and by professional artisans, it’s equally accessible for hobbyists and beginners looking to explore this skill. If you’re curious about mastering thread cutting, this guide will provide all the essential information to get you started.

Why Thread Cutting is Worth Learning

In today’s world of readily available hardware and customizable components, you might wonder why thread cutting still holds value. The truth is, knowing how to cut threads opens up countless opportunities. By mastering this skill, you gain the ability to fabricate components tailored precisely to your requirements, saving both time and money. Moreover, if you encounter damaged threads, understanding thread cutting allows you to repair them effectively. Additionally, being able to adapt non-standard parts by adding threads expands your creative freedom significantly.

External vs. Internal Thread Cutting

Threads can be categorized into two main types: external (like screws) and internal (like nuts). Despite their differences, the basic principle remains the same—sharp cutting edges remove material to form the thread grooves. However, the practical application varies depending on whether you’re cutting external or internal threads.

Cutting Internal Threads

To create internal threads, you’ll need a set of screw taps. Before starting, though, it’s crucial to prepare the base hole using a spiral drill bit of the correct size. The hole must be neither too large nor too small; otherwise, the thread won’t form properly or could damage your tools. You can determine the ideal hole size using a formula or reference charts. Chamfering the hole’s edge beforehand is also advisable to ensure smooth cutting.

Cutting External Threads

For external threads, such as those on bolts or screws, a die is used instead. Prior to cutting, select the appropriate bolt and check its pre-work diameter, which functions similarly to the base hole diameter for internal threads. Again, reference tables can help guide you here. Chamfering the bolt end is another critical step before threading. Once prepared, position the die vertically and apply gentle pressure to begin cutting the thread.

Hand or Machine Thread Cutting?

Thread cutting can be done either manually or mechanically, each method having its own set of pros and cons. Manual thread cutting offers flexibility—you can do it anywhere without needing access to electricity or expensive machinery. However, using a stationary drilling machine drastically reduces cutting time, especially for large-scale projects. Machines also reduce human error, leading to more consistent results.

Manual Thread Cutting

When cutting internal threads manually, a multi-part hand thread tap set is essential. These kits usually include tools for both coarse and fine threads, allowing gradual cutting that reduces physical strain. Alongside the taps, you’ll need an operating tool like a tap wrench or ratchet to guide the process smoothly. Similarly, external threads can be cut manually using a die and die holder. Maintaining the die’s alignment is key here, and a die guide can prove invaluable.

Machine-Assisted Thread Cutting

For machine-based thread cutting, you’ll need a machine tap capable of completing the entire threading process in one go. Ensure your drilling machine is designed for thread cutting and preferably equipped with a thread cutting chuck. An automatic feed system enhances efficiency during machining. Note that machine taps should never be used in handheld drills or cordless screwdrivers due to the high risk of misalignment. Adequate cooling is also vital during machine operations to prevent overheating and tool wear.

Whether you prefer doing it by hand or with a machine, BAER has everything you need to get started. As a trusted screw tap manufacturer, we offer a wide range of products including screw taps, thread cutting dies, twist drill bits, countersinks, and more. Explore our online shop today and take your thread cutting skills to the next level!