Which Flexible Shaft Should I Use for 38mm Pipes?

Working with 1.5-inch (38mm) pipes often raises a key question: which flexible shaft will handle the job effectively? The truth is, this pipe size presents unique challenges that most standard shafts aren’t well-equipped to deal with. Let’s explore your options and how to make the best of them.

Is Any Flexible Shaft Really Suitable?

In short, not really. Although a 6mm shaft is small enough to fit inside a 38mm pipe and offers a decent amount of flexibility, it tends to run into problems—especially when navigating several bends. The shaft simply doesn’t bend sharply enough to cope with the tighter turns typical in these smaller pipes.

What Makes It Difficult?

The challenge comes down to the flexible shaft’s bending radius. A 6mm shaft works well in 50mm pipes because its flexibility matches the arc of a 90-degree bend in those larger pipes. But in 38mm pipes, the bends are tighter, and the shaft starts to resist, making progress slow or even impossible.

A Tip That Might Help

If using a 6mm flex shaft in a 38mm pipe is unavoidable, there’s one tweak that could reduce snagging: remove the sleeve bearing from the shaft’s end. This bearing, while helpful in other settings, can catch on corners and edges inside small-diameter pipes. Without it, the shaft might move more freely—but keep in mind, this is still far from an ideal setup.

In Summary

While it’s technically possible to use a 6mm flexible shaft in a 38mm pipe, it’s rarely practical. The tool isn’t built for that tight a space, and it’s likely to struggle, especially in pipes with multiple bends. Removing the sleeve bearing may ease some of the difficulty, but if you can, it’s better to use a setup that’s actually designed for small-diameter piping—or avoid the task altogether until more suitable tools are available.

To watch a video we made on this topic, please follow this link.