Here’s a detailed, industry-level guideline (checklist + warning signs) for assessing a pre-owned Okuma Multus B400-W (turn-mill / multitasking center, Japan-built) before purchase. I’ll first outline known spec features so you know “what to expect,” and then walk through what to inspect, test, and how to interpret findings. Use this as your on-site due diligence tool.

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Known baseline specs & architecture (so you know what “good” looks like)

Before you inspect, you should collect or verify the as-built (or target) spec sheet. Below are typical specs for the Okuma Multus B400-W as known in industry listings and brochures:

Spec	Typical Value / Range*
Machine type	Multitasking turn-mill (turning + milling + live tools + sub-spindle)
Number of axes	7 (or sometimes up to 8, depending on configuration)
Swing / turning diameter	~710 mm (≈ 27.95″)
Machining / working length (Z)	~1,500 mm (≈ 60 in)
X travel	~690 mm (≈ 27.17″)
Y travel (milling offset)	± ~115 mm (i.e. ±4.5″) or ~230 mm total depending on spec sheet version
B-axis tilt / indexing	225° indexing (e.g. –30° to +195°) with high resolution (0.001°)
Main spindle speed (turning)	~38 – 3,800 rpm (some sources indicate up to 2,800 rpm in certain versions)
Milling / live-tool spindle speed	Up to ~10,000 rpm in many configurations
Tooling / turret	Capto C6 tooling for milling / live tools
Control / electronics	Okuma OSP-series (e.g. OSP-P or OSP-200L)
Weight / footprint	Very heavy (20+ tons), large footprint; e.g. “machine weight ~34,000 lbs” in one listing.

* These are typical values, but specific units may differ based on configuration, options, or region.

Because the Multus is a complex multitasking machine (turning + milling + live tooling + B-axis + sub spindle) it has many more potential failure modes than a simple 3-axis VMC or lathe. That makes the inspection even more critical.

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Pre-visit preparation

Before showing up on site, do the following to maximize your inspection effectiveness:

1. Obtain documentation & service history
   • Maintenance logs, repairs, parts replaced, alignment checks, rebuilds, spindle history.
   • Machine hours (turning hours, milling hours) if available (not just “on time”).
   • Control backups, parameter files, calibration records, wiring diagrams, parts list.
   • Any history of crashes, overloads, or collisions.
2. Request a demonstration via video / remote control
   • Jogging axes, running the milling spindle, tool change operations, sub-spindle transfer, simultaneous motion.
   • If possible, ask the seller to perform a “test cut” or run a known part program while you watch.
3. Bring inspection tools & reference hardware
   • Dial indicators, test bars, gauge blocks, edge finders, quality reference bars, maybe a portable vibration meter or stethoscope.
   • Thermal probe or thermometer to check temperature gradients.
   • Your own known “reference part” or master gauge, if feasible.
4. Arrange for technical support / expert
   • If you’re not specialized in Okuma or multitasking machines, bring someone who is (mechanical, CNC, controls).
   • Having someone who can interpret control alarms or servo feedback during inspection is extremely helpful.
5. Check spare parts & local support
   • Are critical spares (spindle bearings, servo modules, B-axis gearboxes, control boards) available in your region (Turkey)?
   • Are there service firms locally who know how to service Okuma OSP controls and multitasking machines?
6. Prepare logistics / installation plan
   • Because this machine is massive and heavy, ensure you know crane, foundation, floor load, power, cooling, utility hookups, transport paths, etc.

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On-site inspection & testing checklist

Below is a detailed checklist and what to look (and listen) for. For each system, I include “good sign,” “acceptable tolerance,” and “red flag / warning.”

System / Subsystem	Inspection / Test	Good Signs / Acceptable	Red Flags / Warning Indicators
Frame, castings, structural	Visually inspect for cracks, repaired welds, distortion, corrosion; check alignment of base surfaces	No cracks, no obvious repair welds, minimal rust, surfaces flat	Weld repairs, cracked castings, twisted base, obvious misalignment
Way covers, bellows, guards	Traverse axes (X, Y, Z, W, B) manually or via slow jog; examine covers for contact, deformation	Covers move freely, no dragging, no holes, no sagging	Bellows torn, sagging, cover hitting tool or table, debris stuck underneath
Ball screws / linear guides / slideways	Jog axis, stop and reverse to check backlash, feel for smoothness, measure with dial indicator	Low backlash (within manufacturer spec), smooth motion across full travel	Excessive backlash, “dead spots,” binding in portions, vibration or chirping noise
Rotary / B-axis / tilt mechanism	Index B-axis, move through full tilt range under load, check for backlash or play in B-axis gear train	Precise indexing, no slop, smooth motion	Backlash in B-axis, jitter, binding near extremes, gear tooth damage
Sub-spindle (W axis)	Transfer a part from main to sub, test tight coupling, rotate sub spindle, run motion	Clean transfer, tight engagement, stable rotation without wobble	Loose coupling, difficulty in part transfer, vibration in sub spindle, poor alignment
Main spindle (turning)	Run through speed range (low to high), measure runout with test bar, listen for bearings noise, check temperature	Quiet across speeds, runout in a few microns, stable temperature	Grinding, knocking, excessive vibration, high heat, wobble in test bar
Milling / live tool spindle	Engage milling spindle, test in axial and radial motion, check live tool speed and stability	Clean operation, stable rpm up to spec, no chatter	Tool chatter, excessive vibration, spindle noise, failure at high rpm
Tool changers / turret / ATC	Cycle tool changes, index turret, test quick change, check tool retention, alignment	Smooth indexing, no misses, tight retention, repeatable, no error alarms	Tool drop, mis-index, slow cycles, worn pockets, collision marks
Servo drives / motors / amplifiers	Cycle each axis at various speeds, full rapid traverse, direction reversal, no drive faults	Stable motion, no alarms, no thermal stress, responsive drives	Drive trips, overheating, axis fault alarms, jittery motion, loss of axis control
CNC control / electronics cabinet	Open cabinet, inspect wiring, cleanliness, fan operation, dust, burnt areas; power on and check control health, I/O integrity, alarm logs	Neat wiring, functioning fans, no burns, control boots cleanly, able to access parameters, I/O OK	Burnt terminals, broken wires, fan failure, error codes on boot, I/O missing signals
Cooling / lubrication systems	Check conditions of coolant (cleanliness, pH, contamination), pumps, filters, piping; check automatic lube system for axes	Clean coolant, functioning pumps, no leaks, good lubrication flow	Clogged filters, leaks, pump failure, poor lubrication, fluid contamination
Chip / debris handling	Run chip conveyors, chip augers, test that chips are removed cleanly, no buildup	Chips flow freely, conveyors run, no jams	Chips stuck or jammed, conveyor motor faults, pile-ups, broken conveyors
Thermal stability / drift	Operate machine for extended time, then re-measure critical dimensions to see drift	Minimal drift after warm-up, stable readings over repeated cycles	Dimensional drift, variation between cold and hot, readjustments required mid-cut
Accuracy / repeatability tests	Use gauge blocks, test bars, master parts or CMM to verify positioning at multiple points and repeated cycles	Consistent within manufacturer tolerances (a few microns)	Inconsistent readings, drift, nonlinearity across envelope, variation beyond spec
Full-load / cutting test	If possible, run a real part with typical cuts, watch for chatter, torque overloads, surface finish issues	Stable performance, no alarms, good finish, accurate parts	Chatter, tool breakage, unstable paths, servo overloads, finish defects
Software / control features	Test all features (e.g. collision avoidance, thermal compensation, synchronized motion, B-axis functions, macro routines)	All options functional, collision avoidance works, motion compensation active	Disabled options, missing licenses, errors in kinematics, control crashes under advanced motion
Documentation & spare parts	Confirm presence of manuals, wiring diagrams, parameter backups, parts lists; check availability of spares	Full documentation, ability to source key spare parts locally	Missing documentation, no spare parts catalog, obscure or custom mods without documentation

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Interpreting results & decision criteria

Given the complexity of a multitasking machine like the Multus B400-W, here’s how to interpret what you find:

• Fixable vs. fatal defects
    Minor wear (covers, slight backlash, cosmetic damage) is normal. But major issues—spindle bearing failure, B-axis gear wear, control board failures, severe misalignment—are very expensive to repair.
• Cost of remediation vs. discount
    Use your findings to negotiate. The discount should more than cover parts, labor, downtime, and risk.
• Spare parts & expertise in your region
    If key parts (B-axis gearboxes, Okuma OSP control boards, spindles) are not available locally, even a “good” machine may become a liability.
• Residual useful life & maintenance outlook
    If the machine has high working hours and many subsystems nearing end-of-life, you might be buying a “time bomb.”
• Control / software obsolescence
    A mechanically sound machine with an obsolete or unsupported control is risky. Ensure the OSP is modern or upgradeable.
• Warranty / acceptance period
    Negotiate a post-delivery acceptance period (e.g. 30–90 days) during which you fully test under workload, before final acceptance.
• Transport / reinstallation risk
    Large precision machines tend to shift during transport. Always plan re-leveling, re-calibration, checking alignment after installation.
• Use a weighted scoring approach
    Assign weights to subsystems (e.g. spindle, B-axis, control electronics more critical) and score them. A machine passing in low-weight areas but failing in critical areas should be rejected or heavily discounted.