1. Document & History Review (Before Physical Inspection)

Start by requesting documentation and background from the seller, which can reveal a lot about usage, wear, and risk.

Item	What to Ask / Check	Why It’s Important
Machine nameplate, serial number, build year	Confirms the exact model and vintage; helps check matching parts and know what upgrades / revisions exist.
Factory documentation: schematics, electrical / hydraulic diagrams, spare parts lists, maintenance manuals	Essential for servicing, diagnosing faults, ordering spares, and understanding original tolerances.
Service / maintenance logs	Regular preventive maintenance is a good sign. Look for records of spindle bearings, guide repacking, dressers, drive alignment, etc.
Past repairs / refurbishments / crash damage history	Significant repairs (welds, alignments, parts replacement) may have introduced hidden distortions or fatigue.
Operating hours, load history	Heavy usage, abrasive materials, or continuous operation accelerates wear—knowing this helps set expected component conditions.
Known upgrades / retrofits	Some used machines may have newer control systems, drives or retrofits; you’ll want to know what’s been replaced or modified.
Spare parts included or available	If seller includes spare grinding wheels, dressers, spares for drives, belts, encoders, that’s a plus.
Warranty / representation / return clause	Even a limited guarantee helps reduce risk; a “no return / sold as is” increases your inspection burden.

If the seller refuses to provide meaningful documentation, treat that as a red flag.

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2. Visual / Structural Inspection

Walk around the machine and look for signs of abuse, wear, or structural defects. Many issues manifest visibly first.

Machine Base, Frame & Structure

• Check for cracks, weld repairs, or deformations in the base casting, frame members, or supporting structure. Any structural alteration is a concern.
• Check leveling surfaces and foundation mounting points: are they intact, flat, not warped?
• Inspect the housing, cover panels, guards, doors — missing or damaged panels can allow contaminants in.

Guideways, Slides, Linear Rails & Leadscrews / Ball Screws

• Examine the sliding surfaces (ways) for scoring, pitting, rust, gouges, or uneven wear.
• Check wipers, seals, scrapers and protective covers (bellows, telescopic covers). If way covers are torn or missing, debris may have damaged internal guides.
• Look for signs that lubrication lines or channels have been tampered with or blocked.
• Inspect any ball screws (if used for feeds) or leadscrew drives for backlash, wear or looseness.

Spindles & Grinding Worm / Wheel Spindle

• Examine the grinding worm spindle housing for signs of overheating, seals leaks, discoloration or oil seepage.
• Check the work spindle (gear blank spindle): inspect bearing housings and see if there is noticeable wear or loose parts.
• Look at couplings, splines, mounting flanges: check for fretting, wear marks, or looseness.
• Inspect the dressers and their mechanism, dresser mounting, and axes for travel and rigidity.

Enclosures, Guards, Shields & Chip / Coolant Paths

• Look for coolant leaks, corrosion, or residue around the machine base and interior.
• Check for corrosion or rust internally (from coolant, contamination, or neglect).
• Examine coolant tanks, pumps, piping, hoses, filters, and coolant nozzles: are they intact, clean, and functional?
• Inspect chip guards, shields, venting, and drainage. Poor design or damage may have allowed chip ingress to guideways or critical components.

Electrical / Cabling / Junction Boxes

• Open the electrical panels (if allowed) and inspect for burn marks, melted insulation, discolored components, loose wires.
• Check for proper grounding, neat cable routing, correct shielding, and no “ad hoc” wire splices.
• Look for humidity corrosion, dust accumulation, or signs of water ingress.
• Verify that enclosures are sealed and rated, and that wiring is to industrial grade.

General Cleanliness, Paint & Surface Condition

• A well-kept machine tends to be cleaner, better maintained. A machine covered in grime, chips, oil residue, or rust is suspect.
• Look for physical signs of collisions (knocks, dents) or repairs that hide damage.
• Paint wear and touch-ups may mask earlier damage — examine such areas carefully.

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3. Mechanical / Motion Tests

If possible, power the machine and run through motions (in a safe and controlled manner). Listen, feel, and observe behavior.

Axis Motions & Drives

• Jog each axis (e.g. X, Y, Z, A (swivel), etc.) slowly over full travel. Listen for binding, jerkiness, rough motion, chatter, or slipping.
• Reverse direction and check for backlash or lag; measure approximate backlash by feel or via dial indicator if possible.
• At different speeds, observe smoothness, stability, consistency. No sudden jumps, drift, or hesitation should occur.
• Under no load, monitor servo / drive currents: significant variation or high draw may indicate issues.

Spindle / Worm & Workpiece Rotation

• Run both work spindle and grinding worm spindle (if independent) through their rpm ranges. Listen for bearings noise, rumble, grinding, vibration.
• Use a dial indicator or test arbor to check runout / radial runout of the work spindle and mounted parts.
• Observe temperature rise over time; excessive heat may indicate worn bearings or misalignment.

Dressing Mechanism & Dresser Axis

• Move the dresser over its full range; check for smooth motion, no binding, and precise movement.
• Engage the dresser with grinding wheel (if safe). Ensure it properly engages, retracts, and returns neatly.
• Check dresser axis feedback, encoders, and motion repeatability.

Couplings, Gearing & Power Transmission

• Under motion, listen for gear noise, mesh errors, backlash, looseness in couplings or gearboxes.
• Watch for vibration or resonance emerging at certain speeds or travel positions.
• Check for play in couplings, splines, or universal joints.

Homing / Reference Moves / Soft Limits / Limit Switches

• Command homing cycles (if machine supports) and check repeatability of the reference position.
• Test limit switches or boundary conditions and observe whether soft limits and hard interlocks respond correctly.
• Attempt to jog to machine extremes and verify that limits trip properly and safely.

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4. Accuracy, Calibration, Tolerances & Tests

To quantify the condition, perform precision tests and compare against known standards or tolerances (if the original specs are available).

• Use calibrated test arbors or gauge parts to grind a test gear or dummy workpiece; measure results (tooth profile, runout, concentricity, surface finish).
• Perform backlash / positional accuracy / repeatability tests on axes using dial indicator or laser interferometer if available.
• Check gear tooth quality (e.g. flank deviations, profile errors) after a test grind.
• Evaluate thermal drift: run a machining cycle, then measure before/after to see how the machine shifts with heat.
• Check the parallelism / squareness / carriage alignment of axes over full travel.
• For the dresser and grinding wheel axes, check whether commanded position correlates accurately with measured movement.

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5. Control, Electronics & Software

The control, feedback loops, and electronics are critical in gear grinding (precision, synchronization, compensation, etc.).

• Power up the control system; observe boot sequence, error messages, and alarms.
• Access diagnostics, logs, alarms, and history. Look for repeated or major errors.
• Run sample programs, load part files, simulate motions. Check that the machine responds correctly.
• Inspect HMI (operator panel), keys, knobs, displays: ensure they function properly, with no ghosting or dead zones.
• Test connectivity (Ethernet, USB, fieldbus, etc.). Ensure you can interface with external systems or backup/restore programs.
• Check the firmware / software version: if outdated or obsolete, upgrades may be costly.
• Inspect drive controllers, amplifiers, encoders, feedback modules. Look for overheating signs, capacitor bulging, burnt traces, or corrosive damage.
• Verify feedback loops (servo / encoder signals) respond properly; check signal integrity, noise, or inconsistencies.
• Ensure safety interlocks, emergency stops, limit circuits, and safety logic are functional and not bypassed.

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6. Hidden Risks & Red Flags

Be especially vigilant for these warning signs; multiple red flags may indicate the machine is a risky buy.

• Structural cracks, weld repairs, distortions, or frame deformations.
• Excessive wear, scoring or damage on guideways or slides.
• Spindle bearing noise, vibration, or unstable run behavior.
• High backlash or sloppy motion in axes or couplings.
• Dressers that don’t move smoothly, or defective dresser axes.
• Gearbox or coupling looseness, excessive wear, or noise under drive.
• Electrical panels with burnt or damaged components, corrosion, or sloppy wiring.
• Control or software components missing, damaged, or obsolete.
• No spare parts, no documentation, or limited support.
• The seller refusing live testing, operation under load, or only offering “visual inspection” is a red warning.
• Non-OEM modifications, patchwork repairs, or undocumented changes in drives, axes, or mechanics.
• Significant coolant / debris contamination internally, rust, or chip ingress.
• Inability to source grinding wheels, dressers, encoders, or critical subsystems in your region.

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7. Spare Parts, Serviceability & Future Support

Even a well-functioning used machine needs parts and maintenance eventually. Before buying, assess:

• Availability of spare parts: grinding worms, work spindles, bearings, drives, dressers, encoders, couplings, guide parts, controller modules.
• Lead times and cost (especially for imported Swiss parts).
• Are local service / field technicians familiar with Reishauer machines? Are spares stocked by authorized dealer in your region? Reishauer USA maintains stocks of critical spares in Illinois for U.S. operations.
• Whether the control / firmware is supported, upgradable, or obsolete.
• Ease of disassembly, alignment, recalibration, and rebuild.
• Whether you can acquire new grinding wheels, dressing tools, and clamping / fixturing modules.
• Whether the seller can train your operators / service personnel, or assist with startup.

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8. Field / Trial Run (if possible)

If the seller permits, run the machine under realistic loads or test cycles to see behavior under stress.

• Grind a test gear or dummy blank; monitor for anomalies, chatter, change in sound. Inspect finished gear quality.
• Increase load gradually; observe spindle and drive behavior.
• Monitor thermal drift, accuracy over time.
• After the run, inspect dressers, grinding wheel wear, internal components for signs of distress.

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9. Summary: Key “Must-Pass” Criteria

Before you commit, ensure the candidate machine passes these essential checkpoints:

1. Structural integrity — frame, base, bed are sound (no cracks, distortions, heavy repairs).
2. Guide / slide condition — no severe wear, corrosion, or damage.
3. Spindle & worm integrity — smooth, quiet operation, minimal runout, stable under full speed.
4. Motion axes & drives — smooth, backlash-free, no jerks, predictable behavior.
5. Dresser mechanism — precise, responsive, no binding.
6. Control & electronics — functional, responsive, with valid diagnostics, not heavily modified or obsolete.
7. Wear & parts status — spool bearings, couplings, gearboxes, etc., in reasonable condition.
8. Field performance — under load, machine produces acceptable quality parts without instability.
9. Parts & support availability — critical to long-term viability.
10. Documentation / history / transparency — seller must provide maintenance records, repairs, upgrade history.

A machine that checks the majority of these boxes (especially the critical ones) is worth serious consideration.