Several users have reported concerns about motor temperatures, especially on Joint 6 (the wrist motor closest to the tool). This motor works the hardest because it carries the entire tool weight at the end of the arm. Here's what we know from community experience across FR5, FR10, and FR20 models.
Reported temperatures from the community
| Condition | Joint 6 temp | Ambient | Verdict |
| Morning, light use, FR5 | 42°C | 21°C | ✅ Normal |
| Afternoon, under load, FR5 | ~60°C | ~25°C | ⚠️ Getting warm |
| FR5 with hot glue gun (170°C tool) | 60°C+ | Variable | ⚠️ Heat radiating from tool |
| FR10/FR20 idle, light use | 40-50°C on axes 1,2,6 | Room temp | ✅ Reported as normal for these models |
Official specs
From the manual: maximum allowed ambient temperature is 45°C. However, there is no published spec for maximum joint motor temperature. The 45°C figure refers to the room/environment, not the joint itself — internal components (CPU, motors) will always run hotter than ambient.
Reference: manual.fairino.support — Installation
Common causes of elevated joint temperatures
- External heat sources: Hot glue guns, welding torches, heated tools near the joint. Even with isolation, radiant heat transfers through the robot arm. Try to maximize the distance and insulation between the heat source and Joint 6.
- Payload at or near the limit: An FR5 carrying 2kg+ at full extension will stress Joint 6. Make sure your payload settings (mass + center of gravity) are accurate in the WebApp.
- Incorrect payload/inertia settings: If inertia values are at defaults (0), the motor overcompensates. Go to Settings → Payload → Advanced and enter measured Ix/Iy/Iz values.
- Continuous high-speed operation: Temperatures build up over hours of non-stop cycling. Consider adding brief pauses or reducing speed if thermal limits are a concern.
- Hose/cable tension: A glue hose or welding cable that "holds" the wrist creates constant resistance that the motor must fight against.
Occasional "shaft" alarms
Some users report intermittent "shaft 3" or similar alarms that may be heat-related. These typically occur during extended operation in warm environments. If you see these, check temperatures and consider reducing duty cycle.
What to do
- Monitor joint temperatures through the WebApp (visible in the robot status panel)
- Verify payload settings match reality — mass + center of gravity + inertia
- Ensure adequate heat isolation if using hot tools
- If consistently >55°C on any joint, consider reducing speed, duty cycle, or adding cooling
- For the control box overheating — see the separate thread on fan noise and cooling solutions