How Much Torque Will a Drain Cleaning Flexible Shaft Transfer?

When using flexible shafts for drain cleaning, selecting the right drill settings and understanding torque limitations is crucial. This guide walks you through everything you need to know to avoid damaging your equipment or the pipe you’re cleaning.

---

Why Torque Matters

Torque plays a critical role in how effectively your flexible shaft operates. As shaft length increases, torque decreases — meaning longer shafts transfer less force to the cleaning chain. If the shaft is pushed beyond its torque limit, it can fail, potentially causing damage and downtime.

Keep in mind: Power = torque × RPM
So if you increase RPM, torque must drop (assuming constant power).

---

Recommended Operating Speed for Drain Cleaning

For most heavy-duty cleaning applications, operating around 3,000 RPM is effective — but only if your system can safely deliver the required torque at that speed.

---

Flexible Shaft Torque Reference Table

The table below shows static failure torque values obtained from field testing with a linear fit calculation. This helps estimate how much torque each shaft size can handle across various lengths:

Shaft Size	5m	10m	15m	20m	25m	30m
6mm	1.19 Nm	1.35 Nm	1.51 Nm	1.67 Nm	1.83 Nm	1.99 Nm
8mm	3.85 Nm	4.51 Nm	5.17 Nm	5.82 Nm	6.48 Nm	7.14 Nm
10mm	2.80 Nm	4.00 Nm	5.20 Nm	6.40 Nm	7.60 Nm	8.80 Nm
12mm	10.75 Nm	10.76 Nm	10.76 Nm	10.77 Nm	10.77 Nm	10.78 Nm

---

Choosing the Right Drill

A 60 Nm drill is usually sufficient for short or small-diameter shafts. However, for longer shafts or tougher cleaning tasks, a higher torque drill (170 Nm) is recommended. While your shaft may have a lower static failure point, in real-world use it won’t run at full torque continuously — a stronger drill provides better control and reliability.

---

Watch: How to Adjust Your Torque Limiter

To protect your shaft and maximize performance, it’s essential to correctly set your torque limiter.
Watch our quick instructional video here.

---

Conclusion

By matching your drill torque and RPM to the appropriate shaft diameter and length, you’ll avoid costly failures and ensure your drain cleaning setup works smoothly. Use the reference table above as a quick guide to make safe, effective decisions every time.