25/09/2025 By CNCBUL UK EDITOR Off

Avoid Costly Mistakes: Professional Tips for Purchasing a Pre-Owned / Second-Hand / used Excel SL 500/1500 CNC Lathe

Here’s a thorough, professional checklist and advice set to help you avoid costly mistakes when buying a pre-owned / second-hand Excel SL 500/1500 CNC lathe (or any large CNC turning center). The goal is to spot hidden issues before purchase, assess the real risks, and negotiate smartly.

1. Know what you really need & what “SL 500/1500” means

Before evaluating any particular machine, establish your specifications and requirements, so you can spot mismatches or overpaying. For “SL 500/1500,” confirm:

What the “500 / 1500” refers to (e.g. swing over bed, turning length, spindle bore, distance between centers).
Whether the machine is single spindle, twin spindle, bar feed ready, turret type, or has live tooling.
Control system (FANUC, Siemens, Mitsubishi, proprietary Excel, etc.), version, and compatibility with your existing CAM/NC environment.
Required tolerances and surface finish for your workpieces, versus what the used machine can reliably deliver.
Workpiece material mix, cycle times, rigidity, and throughput demands.

Having that “target spec” in mind will help you spot when a machine falls short (even if it “looks good”).

2. Documentation, history & provenance

One of the most critical indicators of how well a machine will perform going forward is how well it has been maintained and documented.

Maintenance and service records: spindle rebuilds, axis rebuilds, retrofits, major repairs.
Original manuals, electrical schematics, parts lists & wiring diagrams: these are essential for future troubleshooting or repairing.
Control software backups, custom macros, parameter settings: ensure you get copies and backups of everything.
Serial numbers, build date, upgrade history: helps you check with manufacturer or experts whether particular parts or controls are still supported.
Usage logs / hours in each axis / power-on hours vs cutting hours: a machine may have many hours but few cutting hours (less wear).
Previous application(s): heavy duty cutting? Long bar runs? Interrupted cuts? These influence wear patterns.

No documentation or very spotty history is a red flag.

3. Structural & mechanical condition

This is where major hidden cost risks lie. Even small misalignments or wear can cost a fortune in repairs, rework, or scrap.

a) Bed, guideways & slides

Inspect the bed ways (flat, V, or combination) for wear, scoring, corrosion, pitting.
Use a long straightedge, precision level, dial indicators or laser alignment to measure flatness over the full travel.
Check for twist, sag or bent structures.
Check movement at full travel in each direction and measure whether errors accumulate.

b) Ball screws / lead screws, nuts & backlash

Measure backlash in each axis (typically X and Z in a lathe). If excessive, it may not be compensatable.
Inspect the nuts for grease leakage, play, wear.
Turn the axes manually (if possible) and feel for stick/slip or binding.
Check coupling condition (e.g. flexible couplings, linkages) between the motor and screw.

c) Spindle, bearings & chuck / nose

Check spindle runout (radial and axial) with a high-precision dial indicator.
Listen and feel for bearing noise at various speeds.
Inspect for heat—run the spindle unloaded for a while and measure temperature.
Look at spindle taper, wear, keyways, retention mechanism, drawbar.
Inspect chuck, jaws, centering mechanisms, chucks’ runout.

d) Tailstock (if present) and other supporting components

If lathe has a tailstock, check alignment (concentricity with spindle).
Inspect its travel, locking, quill, and wear.
Any supporting components like steady rests, follow rests, sub-spindles, live tools: test their functionality.

e) Tool turret, tooling systems, live tooling (if applicable)

Inspect the turret slides, locking mechanism, indexing accuracy.
Check toolholder condition, clamping force, repeatability.
For live tooling: inspect bearings, coupling, coolant passages, speed/torque behavior.
Check for vibration or looseness in tool mount.

f) Coolant, lubrication, hydraulics & chip handling

Check coolant pumps, pipes, collection tank, filters, contamination, leaks.
Inspect lubrication lines, automatic lubrication systems, distribution to slides & screws.
Hydraulic systems (if used for turret, tailstock, chuck) — test pressure, valves, leaks.
Chip conveyor / chip removal systems: motor, belts, cleanability, blockage history.

4. Electrical, control & CNC systems

Very often, an otherwise mechanically sound lathe becomes a headache due to electronics or incompatibility.

Verify the control brand, model, version, serial number, and whether spare parts or boards are still available.
Power up the machine in steps: check for shorts, leakage, blown fuses, unstable voltage.
Test all axes under control: does each axis move smoothly, respond to commands, reverse direction without wild backlash?
Inspect all cables, connectors, cable carrier systems: broken insulation, brittle wires, cracked plugs, intermittent wiring are common in old machines.
Check servo drives, amplifiers, motor controllers for overheats, warnings, signs of burn or repair.
Verify feedback devices (linear scales, encoders, resolvers) — ensure signals are stable, no dropouts, no noise.
HMI / operator panels: test all keys, displays, screen responsiveness, no error codes on boot.
Confirm that all custom macros, param files, offsets, tool tables are present and transferable.
Check that the CNC system can integrate with your CAM, tooling software, DNC / network connectivity you intend to use.

If the control is proprietary or obsolete with no replacement availability, that’s a big risk.

5. Functional / cutting test & acceptance trials

You must see the machine working under realistic conditions before finalizing.

Bring or ask for representative test parts or fixtures.
Run full-length axis travel under load (with tooling and workpiece) and monitor for stalling, chatter, lag, vibration.
Perform a lathe “repeatability test”: move away and return to a reference position, check error.
Turn a test piece and measure diameters, taper, cylindricity, concentricity, finish, runout.
Test multiple tool changes, rapid movements, feed transitions.
Monitor thermal drift over a longer run (temperatures, dimensional drift).
Use dynamic tests: e.g., high-speed cuts, interrupted cuts, small depths to provoke problem zones.
Pressure test hydraulic or turret systems under load (e.g. tool clamping pressure).
Confirm that all safety interlocks, home return, zero return routines, emergency stops work correctly.

If seller refuses or restricts your access, it’s a red flag.

6. Alignment, calibration & geometry

A used machine may require re-alignment, and misalignment is a major cause of poor accuracy.

Inspect whether the machine was recently (or ever) aligned: obtain alignment reports, laser or ballbar results.
Perform your own alignment checks: cross slide perpendicularity, spindle axis squareness, tailstock alignment, tool turret indexing accuracy.
Check for backlash compensation limits and whether the machine’s control parameters allow suitable adjustment.
Verify whether linear scales (if present) and compensation tables are accurate and serviceable.

If the base is warped, foundations moved, or wear too high, realigning could cost more than buying a better machine.

7. Spare parts, support & upgrade path

One of the biggest “gotchas” is: you get the machine working initially, but soon you need a part or a control board, and it’s unavailable or cost-prohibitive.

Confirm availability (regionally or globally) of critical spares: servo motors, amplifiers, CNC boards, control modules, encoders, bearings, turret parts, tooling.
Ask about whether the manufacturer or third parties still support this model.
Determine whether common retrofits or upgrades (new control, spindle rebuild) are possible with the machine’s frame and structure.
Check what tooling, collets, chucks, adapters the machine uses and whether those are still produced or easy to source.
If using live tooling, check for parts support (motors, spindle bearings, drive electronics).
Check if any software licensing / dongles / keys are proprietary and whether they can be transferred or replaced.

If the machine is obsolete with no support, it is a serious long-term risk.

8. Negotiation & contractual safeguards

Use all your inspection findings as leverage in price negotiation. Also protect yourself via contractual terms.

Insist on conditional acceptance: final payment only after the machine passes a full acceptance test you define (e.g., test part dimensions, repeatability, runout).
Ask for a warranty period for critical subsystems (spindle, drives, control) even if short (e.g. 30–90 days).
If possible, include a clause for seller remediation of specified defects discovered in a post-installation test period.
Allocate risks: which party pays for transport, rigging, leveling, final alignment, site modifications, and corrections after installation.
Define acceptance criteria quantitatively (dimensional tolerances, runout, repeatability, error limits).
Ask for spares kit or consumables (belts, filters, seals) to be included.
Capture all promised documents (manuals, backups, parts lists, software) in the contract.

9. Transport, installation & commissioning

Even a mechanically perfect machine can be ruined in shipping or poor setup.

Verify machine weight, dimensions, lifting points, clearances.
Inspect how the machine will be moved (broken down or whole), securing, and whether structural integrity will be maintained.
After delivery, plan for re-leveling / re-grouting / anchoring. In many cases foundations shift during move.
Plan for dust, humidity, temperature control in the installation environment (thermals affect accuracy).
Allow for a commission period to verify performance under production loads before treating it as “accepted.”
Budget for utilities, power, coolant, ventilation, chip handling, cabling, grounding, safety guards.

10. Red flags & deal breakers

Here are signs you should walk away, or insist on large discounts:

Seller refuses or severely limits your inspection or functional tests.
Major structural repairs or welds in bed, frame, slides without supporting documentation.
Spindle with unknown or poor history, or bearing noise at idle.
Excessive backlash in axes not compensatable in control.
Control is proprietary, obsolete, non-serviceable, or lacks spare parts.
Wiring, connectors, cable carriers in poor condition, corroded or brittle.
No documentation, missing manuals, missing software backups.
No spare parts support or upgrades possible.
The cost to realign or repair wear is comparable to a better machine.
Machine has been in harsh or inappropriate service duty (e.g. heavy interrupted cuts, abrasive environment) without service history.