Below is a structured “due diligence checklist” and set of professional tips targeted to buying pre-owned / surplus / used machines like the CHETO PWN / CHETO deep–hole drilling + milling systems (Portugal-built). Because these are high-precision, multi-axis, hybrid machines, the risks are greater than buying a used simple CNC mill or lathe. Use this as a “red flag / risk mitigation” guide.

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Why extra care is needed with CHETO / deep-hole + milling machines

First, some context and peculiarities that make this type of machine riskier to buy used:

• CHETO’s PWN or IXN series machines combine deep-hole (gun drilling or BTA) with milling, tapping, boring, etc.
• They are complex, with multi-axis kinematics, specialized spindles, high-pressure coolant systems, automatic tool changers (for both deep drill and milling tools), chip management, control systems integration, thermal compensation, etc.
• Because of that complexity, degraded subsystems (drive axes, coolant, control electronics, sensors) can cascade into major errors or uptime loss.
• Replacement parts (especially for CHETO-specific or deep-hole drilling tooling, control boards, high-pressure pumps, encoders) may be expensive or hard to source, especially for older or custom-configured machines.

Given that, your buying process should be more cautious than for “ordinary” used CNC milling machines.

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Pre-Purchase Checklist & Risk Mitigation Steps

Below is a structured checklist. Where possible, see / test / verify in person or via video/demonstration. If buying at a distance, you may insist on a “factory witness / third-party inspection”.

Subsystem / Area	What to check / test	Why / What can go wrong	Acceptable tolerances / red flags
Machine history & documentation	– Get full service logs, repair history, original documentation (manuals, wiring, alignment sheets). – Ask for as-built specs, original factory calibration certificates. – Ask about any modifications, retrofits, or “unofficial repairs.”	Hidden damage or abuse history; undocumented modifications can conflict with geometry or control.	Absence of logs is a red flag. Lack of documentation of calibrations or alignments is a negative.
Spindle & deep-hole drilling head	– Run the spindle up and down (forward/reverse) at full speed; listen for noise, vibration, heating. – Check spindle taper & bore (e.g. tool held, mark test). – Inspect seals, bearings, cooling / lubrication to spindle. – For gun-drilling / deep drilling module: check coolant pressure, flow, seals, pump, return lines, filtration. – Run a sample deep-hole drill in a test block to see quality, straightness, drift.	Bearing wear, misalignment, worn taper, leakage, impaired coolant delivery—all can ruin deep-hole performance.	Abnormal noise, chatter, vibrations, oil leakage, uneven heating, or poor test drilling results are red flags.
Linear axes, slides, ballscrews / guides	– Jog each axis at full traverse, observe smoothness, accelerations, decelerations, any stalling or servo warnings. – Listen / feel for “grumbles,” “rumbles,” or unusual whines. – Move axes full forward → full reverse rapidly to detect backlash or play. – Retract covers / way guards and inspect slideways, gibs, lubrication and look for scorings, wear, damage. – Check linear encoder readings vs commanded movement (verify scale accuracy). – Check condition of limit switches, homing sensors.	Worn ballscrews, guideways, backlash, linear bearings wear strongly degrade precision. Repairs are expensive.	Excessive backlash, noise, binding, uneven movement, or large drift (> a few microns) is unacceptable.
Kinematic accuracy / geometry	– Do a “test part” or “NASA test piece” (e.g. a cylinder with a square on top, rotated, etc.) and measure to check geometric precision (squareness, circularity, tramming) as in machine-tool inspection protocols. – Use a dial gauge on the spindle and tram it across a known cylinder to check runout or tilt. – Check angular axes (B, A) if present for rotation accuracy, binding, backlash. – Thermal compensation behavior: after warming up, re-check geometry stability.	Geometry drift is especially critical in deep-hole / mold tooling because misalignment or drift leads to poor hole straightness, intersecting hole errors, which leads to scrapped parts or tool breakage.	If measured discrepancies exceed original factory specification tolerances (you should request the spec sheet), that is a red flag.
Tool changers / magazines	– If machine includes automatic tool changer for milling or the gun drill changer, run it through full cycles. – Inspect each tool magazine pocket or holder for damage, retention springs, positional repeatability. – Check motors, actuators, sensors of tool changer arms.	Tool change failure or poor repeatability causes crashes or misalignment.	Any failure, mis-indexing, mechanical binding, or mis-seats in pockets is a red flag.
Coolant / high-pressure systems / hydraulics	– Check condition of pumps, seals, hoses. – Check fluid cleanliness, filters, pressure and flow sensors. – Check piping integrity, leaks, corrosion. – Run coolant under pressure and flow, observe actual performance. – Check chiller units (if present) or temperature control systems.	Degraded coolant system reduces cooling, chip evacuation, tool life, and may cause catastrophic overheating or tool breakage.	Leaks, low pressure, clogged filters, inconsistent flow, or non-functional chillers are red flags.
Electrical / control / servo / drives / electronics	– Inspect control panel, wiring, circuit boards, fuses, cable harnesses for signs of overheating, dust, corrosion, repairs. – Check servo drives, spindle drives: any LED error codes or fault histories. – Check encoder signals, feedback systems. – Power up, check for error messages, alarm logs. – Test I/O, limit sensors, home switches, emergency stop, interlocks. – If remote diagnostics or software modules exist, check their functionality.	Electronic failures can be very costly (obsolete boards, proprietary firmware).	Consistent error codes, warnings, flaky electronics, or boards that look “burnt” or modified are red flags.
Infrastructure / foundation / alignment conditions	– Ensure the machine was installed on proper foundation (mass, level). – Check floor mounting, anchor bolts, base flatness. – Ask whether the machine has ever been moved and re-levelled; shifting may induce alignment issues. – Check leveling screws, shims, base alignment marks.	Misleveling or poor base can induce drift or stress.	If base is warped, corrosioned, or irregular, demanding re-leveling or base repair.
Thermal stability / environment effects	– After warm-up, record thermal drift over time. – Check internal temperature sensors (if machine has them). – Check for heat sources (electrical cabinet, coolant heating) near critical axes.	Temperature effects can cause growth, drift, which in deep drilling cause misalignment over long lengths.	If drift is large or uncontrolled, or the thermal compensation features are non-functional, that is a concern.
Spare parts, tooling, consumables	– Ask exactly which spare parts (wear parts, seals, pumps, encoders, sensors, boards) remain with the machine. – Ask about tooling (gun drills, holders, tool sets) and whether they are included. – Check availability and cost of critical spares specific to CHETO / deep-hole modules.	If a critical spare is obsolete or unavailable, downtime is high risk.	Lack of spare parts, or known obsolete components, is a red flag.
Software, firmware, controls / CNC interface	– Check which control system is installed (Heidenhain TNC, Siemens, Fagor, etc.). CHETO machines reportedly support Heidenhain TNC 640 or optional ones. – Ensure the control/firmware is the correct version for all axes and features, and that licenses / keys are included. – Verify that the kinematics, parameter tables, compensation models exist and are intact. – Test the interface: uploading / downloading part programs, communication ports, remote diagnostics (if available).	If the control is damaged, corrupted, or missing license keys, you may not get full function.	If firmware is missing, corrupted, or the control is unsupported, that’s a major red flag.
Test / acceptance cut, trial run	– If possible, run a realistic test job representative of what you plan to do. – Watch for error messages, tool wear rates, temperature behavior, deviations in part. – Measure the output and confirm that it meets tolerances.	A “demo test” is the ultimate proof of performance.	Failure to meet tolerances or tool breakage is unacceptable.
Transport, disassembly / reassembly risk	– Determine how the machine will be disassembled, shipped, and reassembled. – Get the original rigging drawings if available. – Check whether the machine can be shipped in one piece or must be broken down. – Account for alignment re-commissioning costs at your site.	Damage during move or poor reassembly can degrade geometry permanently.	Underbudgeting for transport & re-commissioning is a common hidden cost.
Warranty / seller guarantees / support	– Negotiate a limited warranty period (e.g. 30–90 days) or performance guarantee. – Ask if there is any remaining manufacturer warranty or service contract transferable. – Ask the seller (or a third-party inspector) to certify key subsystems. – Insist on “as-is, with defined disqualification conditions” if something fails on final check.	A seller backing gives you recourse if hidden defects emerge.	If seller refuses any guarantee, you’re assuming full risk.

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Strategic Advice & Tips (Professional “hidden wisdom”)

• Use a third-party inspection: Even if you trust the seller, hire an independent machine-tool inspector (preferably someone experienced with deep-hole / mold-making machines) to perform a forensic check. Their report can help you negotiate or walk away.
• Define your acceptance criteria in advance: Before visiting or bidding, prepare your “deal breakers” (e.g. max allowed backlash, max runout, max thermal drift). If the machine fails such criteria, walk away.
• Budget for “recommissioning / calibration / refurbishment”: It is quite likely that after transport, you’ll need to re-level, re-survey, adjust geometry, calibrate encoders, compensate axes. This cost can be tens of thousands USD/EUR depending on complexity.
• Check parts / serviceability in your region: If you’re in Europe, verify whether CHETO or authorized distributors can supply spare parts, support, calibration, field service. It’s no use to purchase a machine whose parts must come from Portugal with long lead times or import costs.
• Obsolescence risk: Even if a used machine works today, its control electronics, boards, sensors, firmware may no longer be manufacturable. Ask about the “end-of-life” status of components. For machines older than ~10–15 years, this risk increases.
• Request to run under full load: The seller should run the machine under conditions close to your worst-case operation (heaviest workpiece, deepest hole) to reveal hidden instabilities or overloads.
• Check alignment before and after test run: If possible, measure geometry before test cuts, then after running for some hours under load, re-check to see if drift or loosening occurred.
• Liquidity in spare tooling / consumables: Ensure you can source gun drills, deep-hole tooling, holders, high-pressure nozzles, abrasive consumables locally or via fast supply channels. Even if the machine is perfect, if tooling is unavailable, you’re stuck.
• Negotiate price cushions: Use the defects you found as negotiation points. If the seller won’t budge, insist on retaining part of the payment until successful re-test after installation at your site.
• Aliasing / job matching: Be absolutely sure the machine’s capacity (axis travels, drilling stroke, spindle power, torque, coolant pressure) matches not just your current jobs but the “worst-case” you may want in future. CHETO’s spec sheets (e.g. for IXN / PWN) list those parameters (spindle rpm, torque, stroke, etc.).
• Check one-off vs standard machine: If the unit was custom-modified by a user, some parts or dimensions may differ from standard CHETO machines, making spare parts or documentation mismatched.
• Don’t skip the “cold start” check: Ask the seller to power it off overnight (or simulate a cold start) and then boot up and move axes, to see if any failures only appear when cold.

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Common Mistakes / Pitfalls (and how to avoid them)

1. Trusting a “nice appearance” — Many sellers polish up the machine (clean covers, paint touch-up) but hide internal wear. Always look under the covers.
2. Skipping test under load — Running idle is not sufficient; problems often manifest under torque, heat, vibration.
3. Ignoring small anomalies (noise, backlash) — Small “quirks” often mask large hidden wear.
4. Underestimating moving / installation / alignment costs — Many buyers get surprised by these “hidden” expenses.
5. Overlooking obsolescence of electronics — Even though mechanical parts may last, control boards or proprietary firmware may be irreplaceable.
6. Lack of warranty or recourse — Accepting “as-is” without protection can lead to a very expensive regret.
7. Failing to check tooling / consumables supply chain — If you can’t get the specialized deep-hole tooling locally, you’re at risk of long delays or excessive costs.
8. Neglecting thermal and environmental stability — The shop environment, ambient temperature fluctuations, dust, etc., affect precision machines heavily.