Lathe Troubleshooting Quick Reference (spindle heat, noise, chatter, dimensional drift)

Spindle runs hotCommon

Bearing temperature trend. According to NTN, temperature rises when operation begins, then settles after a while at a temperature slightly lower than at start-up (normally 10–40°C above room temperature). Settling takes about 20 minutes to several hours. If it keeps rising, stop the machine. Below 100°C is desirable^[1]

Likely cause	What to check	Action
Too little or too much lubricant	Spindle lube oil quantity and drip rate (Haas: bottle test)	Correct to the proper amount^[2][1][3]
Bearing clearance too small, preload too high, or load too high	Check for a high-pitched whine, or measure vibration	Diagnose the bearing condition and repair the spindle if necessary^[2][1][3]
Bearing installed incorrectly	Condition of the assembly	Reinstall^[1](1 source, for reference)
Wrong type of lubricant (a non-specified oil was added)	Type of oil in the tank	Refill with the specified oil^[1][4]
Creep (slip) at the fitting surfaces	Shaft and housing fits	Review the fits^[2][1]
Leaking, kinked, or crushed minimum-quantity lubrication piping, or a solenoid valve that does not operate	Fitting at the top of the pump, tube to the spindle (check whether oil drops are visible), solenoid valve	Retighten or replace fittings, replace the tube, check the solenoid valve^[4](1 source, for reference)
Spindle was left idle for a long time (lubricant has settled) and then suddenly run at high speed	Number of days idle	Haas live tooling: if idle for more than 4 days, warm up for about 20 minutes; if 2 weeks or more, run in for about 2 hours^[5](1 source, for reference)
(Manual) degraded oil in the headstock, poor ventilation, excessive load, shop temperature	Oil temperature at the headstock sight glass (South Bend: below 170°F, about 77°C)	Stop and let it cool, and fix the cause. Change the oil early^[6](1 source, for reference)

Noise from the spindleCommon

Listen to the type and pattern of noise while varying the speed. Hurco says to run the spindle from lowest to highest speed daily and check for abnormal noise or vibration^[7]

Likely cause	What to check	Action
High metallic sound: clearance too small (preload too high), poor lubrication	Vibration measurement, lubricant quantity	Correct the lubricant quantity. If there is no improvement, repair the spindle^[2][1][3]
Irregular noise: clearance too large, foreign matter inside, damaged rolling elements, wrong lubricant	Bearings	Inspect or replace bearings, improve sealing^[2][1]
Low metallic sound or clicking: dents on the rolling surface (indentations from an impact such as a crash)	Crash history, runout and play at the spindle nose	Repair or replace the spindle^[2][3]
Belt wear, looseness, or incorrect tension; pulley misalignment (squealing, uneven rotation)	Belt condition and tension, pulley alignment	Re-tension or replace. Re-tension new belts after 30–50 hours of running (Takisawa)^[3][8][9]
(Manual) worn or broken headstock gears, gear misalignment or insufficient backlash, bad bearings	Gears and bearings in the headstock	Replace gears and bearings, secure backlash^[6](1 source, for reference)
(Manual) loose pulley set screw or key; motor fan rubbing the cover	Pulley, motor fan	Retighten or replace; shim the cover^[6](1 source, for reference)

Chatter or vibration (machine-side causes)Common

When chatter persists after reviewing tools and cutting conditions, check the machine side in order

Likely cause	What to check	Action
Gibs (slide plates) are loose	Carriage, cross slide, and tool post gibs	Adjust the gibs (slightly heavy but not binding; do not overtighten)^[10][6][11]
Saddle is lifting (poor contact of the front and rear slide plates)	Front and rear slide plates of the saddle	Correct the contact^[10](1 source, for reference)
Loose fit between chuck and spindle nose; runout of workpiece or chuck	Chuck mounting, runout	Remount, correct the runout^[10][3]
Machine is out of level, or has been raised too high on the leveling feet	Precision level (0.02 mm/m), leveling feet	Re-level^[3][9][12]
Damaged spindle bearings, spindle imbalance, running at a resonant speed of the machine	Vibration measurement; cut power and coast to see whether the vibration disappears	Change speed up or down in 10% steps to avoid resonance, balance, diagnose the bearings^[3][2]
(CNC) chatter on a workpiece supported by the tailstock: inconsistent thrust force, tailstock misalignment	How the thrust is applied, alignment of tailstock and spindle	Apply thrust by command or pedal, not manual jog; align^[13](1 source, for reference)
Stick-slip at low feed (insufficient or wrong way oil)	Oil film on the ways, type of slideway oil	Lubricate the ways correctly, switch to the specified oil^[14][15][16]

Dimensions drift over time (thermal displacement)Common

Compare room temperature, operating history, and idle time against the dimensional change

Likely cause	What to check	Action
Temperature changes around the machine	Record the room temperature	Warm up so the machine stabilizes thermally. On machines with thermal displacement compensation, use that function^[17][18]
Heat generated by the machine itself, such as the spindle. The spindle's displacement changes greatly both while running and after stopping	Whether warm-up was done; time stopped during setup	Warm up before machining (Hurco warms up a machine that has been stopped for 8 hours). The Machine Tool Engineering Foundation says it has generally been held that 2 hours or more are needed to reach thermal stability, and a warm-up of about 20–120 minutes^[17][7][18]
Heat from machining, coolant temperature	Coolant temperature	—^[17](1 source, for reference)
Hot chips piling up; heat sources such as the hydraulic unit and control cabinet	Chip evacuation	Flush chips away from the cutting area quickly^[19](1 source, for reference)

Dimensions are off (backlash, misalignment, play)Common

Lost motion when feed reverses; size variation between diameters

Likely cause	What to check	Action
(Manual) feed screw nut adjustment has loosened or the nut is worn	Read the play on the handwheel dial (Hardinge HLV-H: up to 2 divisions on the compound rest)	Reduce the play with the adjusting nut. If that does not fix it, replace the screw and nut. Overtightening speeds wear (South Bend)^[11][6][20]
(Manual) lead screw lock nut is loose (moves axially)	Lock nut at the end of the lead screw	Retighten^[6][20]
(CNC) turret center-height offset (the origin may shift after a crash, battery failure, or axis motor replacement)	Measure the misalignment with a lever-type dial indicator	Re-establish the origin and adjust the center height^[9][21](1 source, for reference)
(CNC) feed-axis backlash, gib play	Backlash measurement, ballbar (reversal spikes and backlash show up)	Adjust or compensate (Okuma: ask the distributor)^[12][22]

Turns tapered (not parallel)Common

Compare two diameters in a trial cut

Likely cause	What to check	Action
(Manual) bed is out of level	Check level with a level, and make two trial cuts	Correct with the leveling screws until half of the diameter difference is gone^[10](1 source, for reference)
(Manual) gap piece was not put back correctly after removal (when cutting on the spindle side)	Gap piece	Reinstall correctly^[10](1 source, for reference)
Headstock parallelism is off (OD tapers, face is crowned)	Test bar and dial indicator	Adjust headstock parallelism, then check the turret center height^[9][11]
Workpiece supported by the tailstock: tailstock and spindle misaligned, or thrust pressure wrong	Alignment of both centers, thrust pressure	Align them. Haas distinguishes the two: if the taper is uniform, thrust pressure is insufficient; if it is not uniform, the pressure is too high and the workpiece is deformed^{[6][13][9][11]}

Tailstock problemsCommon

Likely cause	What to check	Action
(CNC hydraulic tailstock) does not move or is slow: position-detection wire pinched by the way cover; solenoid valve not getting voltage or dirty	Inside the way cover, solenoid valve	Fix the pinching; clean the solenoid valve^[13](1 source, for reference)
(CNC) origin drifts: dirty or faulty encoder, low hydraulic pressure, chips on the guide or cover	Encoder, hydraulic pressure, guide	Clean, adjust, or replace; raise the hydraulic pressure^[13][23](1 source, for reference)
(CNC, screw type) noise, position error, backlash: insufficient lubrication of the feed screw and nut, dirt from chips, broken nut	Screw and nut	Clean and grease; replace the nut^[23](1 source, for reference)
(CNC) insufficient thrust or pressure alarm: low tailstock hydraulic pressure, faulty pressure regulating valve	Hydraulic pressure gauge	Raise the pressure; check the regulating valve^[13][24](1 source, for reference)
(Manual) tapered tool will not come out: quill not retracted all the way, taper not cleaned	Quill, taper bore	Retract fully to eject it; clean the taper^[6](1 source, for reference)
(Manual) misalignment: chips or burrs under the tailstock	Tailstock seating surface	Clean it and measure the alignment again^[11](1 source, for reference)

Turret indexing or clamping failureNC

Likely cause	What to check	Action
Supply air pressure or flow is insufficient	Air pressure drop during indexing (Haas: within 10 psi is the guideline)	Fix the air supply^[25][26]
Clamp/unclamp solenoid valve or proximity sensor is faulty	Solenoid valve voltage, sensor input	Inspect or replace^[25](1 source, for reference)
Foreign matter such as chips between the turret and housing (does not seat)	Mating surfaces of the turret	Remove the foreign matter^[25](1 source, for reference)
Internal gear damage (noise when turning), piston seal blow-by	Noise, air leaking from the solenoid valve muffler	Repair by manufacturer service^[25](1 source, for reference)
Misalignment after a crash, battery failure, or axis motor replacement	Measure the misalignment	Redo the origin establishment (it involves parameter operations, so be careful)^[21](1 source, for reference)
Turret oil is low (Hurco TM series: at least half on the sight gauge)	Oil gauge on the front of the turret	Top upThis is a monthly inspection item, not a description that directly links low oil to indexing failure^[7](1 source, for reference)

Lubrication failure alarmCommon

Likely cause	What to check	Action
Low tank oil, or faulty or stuck level sensor (float)	Tank, float movement	Top up; inspect or replace the sensor^[4][27][7]
Clogged suction filter, oil viscosity changed so it cannot be drawn in, stuck check valve	Filter, oil, check valve	Wash or replace the filter and use fresh oil; clean the valve^[27](1 source, for reference)
Main line pressure does not rise: foreign matter in the relief valve, air in the piping, broken or leaking piping	Relief valve, ends of the piping	Clean; bleed air at the ends; replace piping^[27](1 source, for reference)
Run-time setting too short so the pressure switch does not act; level switch contacts mixed up	Controller settings, wiring	Correct the settings and wiring^[27](1 source, for reference)
Oil does not reach some sliding surfaces: clogged distributor (metering unit)	Watch the flow in each line when refilling	Clean or replace the distributor (Hardinge replaces the metering unit once a year)^[27][9][11]
Leak at the pump fitting, pump not primed (air in the piping)	Fittings, air in the piping	Retighten, prime the pump^[4](1 source, for reference)
(Manual) headstock oil does not circulate: clogged suction screen or low oil, air drawn in on the suction side, bad pump	Sight glass, suction screen	Clean the screen and top up, stop the leak, repair the pump^[6](1 source, for reference)

No or little coolant, noisy pumpCommon

Likely cause	What to check	Action
Low coolant level in the tank	Level gauge	Top up^[7][28]
Clogged filter, pump suction, or nozzle; chips piled up inside the machine	Filter, suction port, check valve, hose, nozzle	Clean or replace^[28][9][7]
Dirty or damaged impeller, motor bearing failure, reverse rotation due to wrong phase sequence	Impeller, turn the shaft by hand, phase sequence	Clean or replace; correct the phase sequence^[28](1 source, for reference)
Valve closed, or coolant not turned on in the program or settings	Valve, operating mode and settings	Open the valve; correct the settings^[7][28]
Breaker trips: motor ground fault, seized pump	Insulation between each phase and ground	Replace the pump or cable^[28](1 source, for reference)
Coolant spoils or smells: floating oil left in place, wrong concentration	Floating oil, concentration, pH	Remove floating oil; manage concentration^[29][7]

Hydraulic pressure drops or oil temperature rises (hydraulic unit)NC

Likely cause	What to check	Action
Low oil level, clogged suction strainer or filter, air drawn in through a suction fitting	Level gauge, filter, fittings	Top up; clean or replace; retighten^[24][30][31]
Pump runs in reverse due to wrong phase sequence; oil is cold and its viscosity is high; pressure setting is wrong	Phase sequence, oil temperature, settings	Correct the phase sequence; warm the oil; reset^[24][30]
Bubbles in the oil, coolant contamination (milky or foaming)	Foam and color of the oil	Let the foam out; drain the dirty oil, flush, and refill with fresh oil^[24](1 source, for reference)
Oil temperature rises: fan not running, dirty cooler (radiator)	Fan, cooler fins	Repair the fan; clean the cooler^{[24][30][31][12]}
Oil temperature rises: large internal leakage in the pump or valves, viscosity too low	—	Repair the pump or valves; switch to a higher-viscosity oil^[30](1 source, for reference)
Oil leak: cracked hose, loose fitting, damaged O-ring or oil seal	Both ends of the hose, routing	Retighten (not too much); replace the hose or O-ring^[24][30]

Chuck gripping force drops or workpiece slipsNC

Likely cause	What to check	Action
Out of grease, or non-specified grease	Greasing record	Grease from each nipple and open and close the chuck several times without gripping a workpiece^[32][33][34]
Insufficient hydraulic pressure	Chuck hydraulic gauge	Raise to the set value^[32][33][7]
Jaw stroke is insufficient (jaws are not near the center when gripping)	Base line of the master jaw	Correct the jaw position^[32][33]
Chips have accumulated inside	Stroke	Disassembly and cleaning^[32][33][34]
Draw pipe (connection to the rotating cylinder) is loose	Insufficient stroke	Remove the cylinder and retighten^[32][33][35]
Soft jaw boring diameter does not match the workpiece, or the boring method is wrong	Parallelism of the boring plug or ring, deformation, pressure during boring	Bore the jaws correctly again^[32][33]
Speed is too high (centrifugal force reduces gripping force)	Speed and dynamic gripping force	Reduce to a speed at which the required gripping force is obtained^[32][33][36]
Jaw height is too tall, causing jaw deformation or stretched bolts	Jaws and bolts	Lower the jaw height^[32](1 source, for reference)
(Automatic feeding) chips between jaw and material prevent seating	Jaw contact surfaces	Clean; use jaws shaped to scrape chips out (research example)^[37](1 source, for reference)

Poor chuck gripping accuracyNC

Likely cause	What to check	Action
Chuck periphery and face runout	Periphery and face runout	Retighten the bolts^[32][33]
Dirt on the mounting surface and serrations	Mounting faces	Clean^[32][33][34]
Jaw mounting bolts are under-tightened	Tightening torque	Tighten to the specified torque^[32][33][34]
Gripping force is too high and deforms the workpiece	Gripping force	Reduce the gripping force as far as machining allows^[32](1 source, for reference)

Chuck does not moveNC

Likely cause	What to check	Action
Broken parts, seized sliding parts	Disassembly inspection	Replace parts; repair seized areas with an oilstone^[32][33]
Rotating cylinder is not moving	Piping and electrical system	If nothing is wrong there, disassemble and clean the cylinder^[32][33]
Too much grease	Grease drain hole	Remove the plug and open and close the jaws to push out the excess grease^[32](1 source, for reference)

(Manual) no feed or heavy handwheelGeneral-purpose

Likely cause	What to check	Action
Shear pin (safety pin) is broken (only the feed stops during threading)	Shear pin	Replace^[10][6]
Feed box slip clutch is out of adjustment	Clutch	Adjust (Colchester: usually about a 1/4 turn)^[10][20]
Gibs too tight, chips in the dovetail, or bed is dry	Gibs, sliding surfaces	Clean and lubricate, then readjust the gibs^[6][20][11]
Gears are not engaged, or the carriage lock was left tightened	Lever position, lock	Re-engage the lever; loosen the lock^[6](1 source, for reference)

📚Sources

Items without a mark are those on which two or more materials from different publishers agree. Values and intervals are governed by each machine's specifications. The text is summarized in Kezuriba's own words.