The thresholds to know: 100–120°F is normal operating range. 130–150°F warrants monitoring — note ambient temperature, cutting load, and cycle length before drawing conclusions. 160°F and above means stop production and run the diagnostic checklist. More important than any single reading is trend — if the spindle is running hotter than it used to under the same conditions, something has changed internally.

The five most common causes are: bearing wear or preload loss (the most common internal cause), contamination ingress from wood dust when purge air fails or seals degrade, incorrect lubrication from a previous repair (wrong grease type or too much grease), cooling system issues (blocked fan filters or restricted coolant flow depending on spindle type), and excessive cutting load from dull tools or aggressive feed/speed settings. Always verify cooling and process conditions before concluding the spindle needs repair.

Not immediately — run the diagnostic checklist first. Verify purge air pressure, inspect collets and tool holders, confirm cooling airflow or coolant flow, then run the spindle unloaded at multiple RPM ranges while monitoring temperature. If heat rises quickly even when running unloaded, or if temperature scales proportionally with RPM, removal and inspection is recommended. If the spindle stays cool unloaded but heats only under cutting load, look at process conditions and tooling first.

Yes — this is a common result of improper rebuilds. Electrospindles require precise grease volume. Too much grease increases churning drag inside the bearing cavity, which generates heat and can cause thermal instability. Using the wrong grease type (incorrect viscosity or base oil) produces the same result. If a spindle started running hot shortly after a repair, over-greasing or incorrect grease is one of the first things to check.

Continued operation accelerates the damage cascade: bearing cage failure from thermal fatigue, shaft scoring from bearing fragment contact, stator insulation damage, and eventual rotor imbalance. Each stage adds cost and turnaround time to the repair. A spindle caught at the overheating stage — before shaft or stator damage — is typically a bearing and seal repair. The same spindle run to catastrophic failure can require shaft regrinding, housing work, and balance correction.

Bearing wear — the most common cause of overheating — almost always produces both heat and vibration together. If your spindle is running hot, check for vibration at the same time. Vibration that increases with RPM alongside temperature rise is a strong combined indicator of bearing degradation. Our vibration guide covers the diagnostic steps: Anderson Router Spindle Vibration.

The Anderson-specified maintenance intervals address every controllable heat source. The most critical habits: follow the 3-step warm-up sequence (3,000 / 6,000 / 9,000 RPM, 5 minutes each) before applying any cutting load, verify purge air pressure daily, never use compressed air to clean the spindle or taper, replace collets quarterly regardless of appearance, and allow a 10-minute cool-down with the tool holder removed before shutdown. Full intervals are in the Anderson Spindle Maintenance Guide.

No. Atlanta Precision Spindles repairs the spindle assembly only. We do not service the CNC router frame, linear rails, ball screws, drives, controls, wiring, cooling systems, or other machine-side components. Our focus is exclusively on precision spindle inspection, rebuild, and restoration.