How can I recognize the thread direction of my lead screw?

September 9, 2021 Zoe Moser

What is the difference between left-hand and right-hand threads and how can I recognize the thread direction?

The thread cutting direction right or left can be easily determined with a visual inspection. If you look at the lead screw from the front, you can best see the difference between left-hand and right-hand threads.

Right-hand threads

For lead screws with right-hand thread, the thread flanks rise from bottom left to top right (marked orange in the graph). In production drawings, right-hand threads are often marked with the letters RH. For example: TR20x4-RH.

This model is usually preferred by our customers. However, this is often due to ergonomic requirements, not due to technical differences. The majority of people are right-handed and can therefore apply a greater torque when turning the lead screw clockwise than against it.

Due to the frictional conditions on the wedge, or the inclined plane, tightening a lead screw involves a greater torque than loosening it. The right-hand thread therefore meets these two requirements.

Discover right-hand threads in the igus® online shop

Left-hand threads

A left-hand thread rises from bottom right to top left when viewed from the front. Here too, the thread flanks are marked in orange. An alternative designation is the left rising thread. Left-hand threads are marked with the letters LH. For example: TR20x4-LH.

Discover left-hand threads in the igus® online shop

 What other thread directions does igus® offer?

Thread directions other than left and right, are of course, impossible. But what about a combination of both cutting directions?

Our dryspin® product range includes not only lead screws with right-hand or left-hand threads, but also reverse lead screws. Reverse lead screws offer more flexibility and design freedom for your application.

If you'd like advice on how to determine the best lead screw for your application, contact us. You can also visit this webpage to learn more about dryspin® lead screw assemblies or to try out our lead screw product finder and lead screw configurator to calculate service life, build lead screws in 20 minutes or less, and more.   

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