What is the Bending Radius of Drain Cleaning Flexible Shafts?

When using flexible shafts for drain cleaning, one often overlooked but critical factor is the bending radius—how tightly a shaft can curve without compromising performance or risking damage. This is especially important when working through bends, traps, and offsets in the pipework.

What Is Bending Radius?

The bending radius is the smallest U-shape a shaft can safely form. Exceeding this limit can cause internal stress, shorten the tool’s lifespan, or even lead to shaft failure during operation.

Bending Radius by Shaft Size

Below are typical bending radii for common flexible shaft sizes, both with and without an outer sleeve:

Shaft Ø	Bending Radius (with sleeve)	Bending Radius (no sleeve)
6 mm	8 cm	8 cm
8 mm	13 cm	13 cm
10 mm	17 cm	15 cm
12 mm	21 cm	16–17 cm

Why It Matters

A shaft with a large bending radius may struggle in small-diameter pipes or complex layouts. Choosing a shaft that can flex more easily helps you navigate bends more safely and improves cleaning performance.

This is one of the main reasons we don’t recommend using shafts thicker than 6 mm in 50 mm pipes. For more guidance, check out our video on selecting the right shaft diameter for the job.

Final Tip

When working in older or narrow pipes, always choose a shaft with a tighter bending radius. Avoid forcing the shaft through sharp curves—letting it bend naturally ensures a smoother and safer cleaning process.