Appearance
Refurbishing an older deep hole drilling machine restores 90–100% of original performance at 40–60% of the cost of new. The cast iron structures of older machines do not wear out — the precision components mounted to them do. Replace those and you have a machine that performs like new.
Machine Assessment
Pre-Refurbishment Evaluation
Before committing to a refurbishment, assess the machine's condition to determine whether a full or partial refurbishment is feasible:
| Assessment Area | What to Check | Acceptable for Refurbishment |
|---|---|---|
| Machine base and bed | Cracks, twisted geometry, level | No structural cracks or twisting |
| Guideway surfaces | Scoring, wear pattern, hardness | Damage limited to replaceable surfaces |
| Ball screws | Backlash, visible wear, straightness | Can be replaced or re-ground |
| Spindle | Runout, bearing noise, temperature | Housing undamaged, bearings replaceable |
| Coolant system | Pump condition, tank integrity, piping | Can be overhauled or replaced |
| Hydraulic/pneumatic system | Pump noise, cylinder leakage, valve function | All components replaceable |
| Control system | PLC, drives, operator interface | Can be retrofitted or replaced |
Decision: Partial vs Full Refurbishment
| Refurbishment Level | What Is Included | Cost (% of new) | Resulting Performance |
|---|---|---|---|
| Light refurbishment | Seals, wipers, hoses, coolant pump, control tuning | 10–20% | Restores reliability |
| Partial refurbishment | Above + ball screws, guideway reconditioning, spindle bearings | 30–50% | Restores accuracy and reliability |
| Full refurbishment | Above + spindle rebuild, guideway regrind, new control system, rewiring | 40–60% | Near-new performance |
| Complete rebuild | Full structural reconditioning + new hydraulic system + new coolant system | 60–75% | Equivalent to new |
Spindle Rebuild
Spindle Assessment
| Measurement | New Machine Tolerance | Refurbishment Target | Replacement Trigger |
|---|---|---|---|
| Radial runout at taper | < 0.005 mm | < 0.010 mm | > 0.020 mm |
| Axial runout | < 0.005 mm | < 0.010 mm | > 0.015 mm |
| Bearing temperature | Ambient + 15°C | Ambient + 20°C | Ambient + 30°C |
| Vibration (overall) | < 1.0 mm/s RMS | < 1.5 mm/s RMS | > 3.0 mm/s RMS |
Spindle Rebuild Process
- Disassemble and clean all components
- Inspect spindle shaft for wear, scoring, and runout
- Replace all bearings (angular contact, cylindrical roller)
- Replace seals (coolant and oil)
- Balance rotating assembly (G2.5 or better)
- Assemble and test run at operating speed
- Measure runout, temperature, and vibration
Tip: Always replace the rotary union (coolant seal) during a spindle rebuild. The rotary union is a wear item that costs $800–3,000 — cheap insurance when the spindle is already disassembled.
Guideway Reconditioning
Assessment
| Guideway Type | Typical Wear Pattern | Reconditioning Method |
|---|---|---|
| Flat way with Turcite/B | Worn Turcite layer | Replace Turcite and scrape |
| V-way | Wear at centre of V | Regrind and re-scrape |
| Linear rail | Brinelling from chips | Replace rail and blocks |
| Box way | Gib wear on thrust side | Regrind or replace gibs |
Reconditioning Process for Turcite-Lined Guideways
- Strip old Turcite material from sliding surfaces
- Inspect cast iron way surface for damage
- Scrape cast iron surface to restore geometry
- Bond new Turcite material to sliding surfaces
- Scrape Turcite to match mating surface
- Measure contact pattern (target: 60–80% contact)
- Reassemble and check clearance
Ball Screw Replacement
| Ball Screw Condition | Action |
|---|---|
| Backlash > 0.05 mm but screw surface undamaged | Replace nut only (if available separately) |
| Visible raceway wear or pitting | Replace complete ball screw assembly |
| Bent screw (indicated by periodic torque variation) | Replace complete ball screw assembly |
| Nut preload lost but minimal wear | Re-preload (manufacturer-specific procedure) |
Coolant System Overhaul
| Component | Typical Refurbishment Action | Cost |
|---|---|---|
| Coolant pump | Replace seals, bearings, check valves | $2,000–5,000 |
| Coolant tank | Clean, repair leaks, recoat interior | $1,000–3,000 |
| Piping and hoses | Replace all high-pressure hoses, check pipes for erosion | $3,000–8,000 |
| Filtration system | Replace filter elements, clean housing, check bypass valves | $1,000–3,000 |
| Coolant chiller | Service compressor, replace refrigerant filter, clean condenser | $2,000–5,000 |
Control System Retrofit
Options
| Option | Cost | Capability | Complexity |
|---|---|---|---|
| PLC upgrade only | $10,000–25,000 | Restores basic machine control | Low |
| New CNC control | $20,000–50,000 | Modern programming interface | Medium |
| Full automation retrofit | $50,000–150,000 | Part handling, probing, data collection | High |
Benefits of Control Retrofit
| Old Control Limitation | Modern Equivalent | Benefit |
|---|---|---|
| No data collection | Built-in production reporting | Track OEE and tool life |
| No remote access | Ethernet-enabled HMI | Remote monitoring and support |
| Obsolete parts unavailable | Standard industrial PC | Easier spare parts sourcing |
| Limited program memory | Large storage for programs | Fewer part program limitations |
| No probing or automation interface | Standard interface protocols | Easy future automation |
Cost Breakdown: Full Refurbishment Example
| Item | Cost (20-tonne machine) |
|---|---|
| Spindle rebuild (including bearings and rotary union) | $12,000–20,000 |
| Guideway reconditioning (3 m bed) | $15,000–25,000 |
| Ball screw replacement (2 axes) | $10,000–20,000 |
| Coolant system overhaul | $8,000–15,000 |
| Control system retrofit | $20,000–40,000 |
| Electrical rewiring (partial) | $5,000–15,000 |
| Labour and project management | $20,000–40,000 |
| Total refurbishment cost | $90,000–175,000 |
| Equivalent new machine cost | $250,000–400,000 |
| Savings | 50–60% |
Refurbish vs Replace Decision Framework
| Factor | Favours Refurbishment | Favours Replacement |
|---|---|---|
| Machine age | Under 20 years | Over 25 years |
| Structural condition | No damage to base or bed | Cracked or twisted structure |
| Required accuracy | Original machine spec adequate | New, tighter tolerances needed |
| Available spindles | Spindle type is still relevant | New spindle technology available |
| Control requirements | Simple control upgrade sufficient | Full Industry 4.0 integration needed |
| Coolant pressure | Existing pump pressure adequate | Higher pressure needed for new processes |
| Budget | $100,000–200,000 available | $250,000+ available |
| Timeline | Can tolerate 8–16 weeks downtime | Cannot tolerate downtime (buy new, keep old running) |
FAQ
How long does a full refurbishment take?
Typical timeline: 8–16 weeks from machine removal to reinstallation. Spindle rebuild and guideway reconditioning are the longest lead items. Plan for 12 weeks as a realistic estimate.
Is refurbishment cost-effective for machines over 25 years old?
Only if the machine structure is in excellent condition and the required tolerances are within the original machine specifications. Over 25 years, part availability becomes a problem, and technology advances may make the machine obsolete regardless of its mechanical condition.
Can I refurbish the machine in-house or should I use a specialist?
Specialist companies have the scraping skills, measurement equipment (laser interferometer), and experience required for deep hole drilling machine accuracy. In-house refurbishment is practical only for cosmetic work and minor repairs.
What is the biggest risk in machine refurbishment?
Scope creep. During disassembly, hidden damage is often discovered — a corroded oil line, a cracked manifold, a worn hydraulic pump. Budget 15–20% contingency on top of the estimated refurbishment cost.
Will a refurbished machine hold the same公差 as a new machine?
A properly executed full refurbishment (including guideway regrind and new ball screws) will achieve 90–100% of the original machine accuracy. It will not exceed the original design specification. If tighter tolerances are needed than the machine was originally built to, buy new.
What should I do with the old control system?
Keep the original PLC and drives as spares if the cabinet space allows. Otherwise, properly dispose of electronic waste through a certified recycler. Do not scrap the machine documentation — the electrical schematics and mechanical drawings are valuable for the machine's remaining life.
Refurbishment feasibility and cost depend on machine condition, age, and availability of replacement parts. Consult a qualified machine tool rebuilder for a specific assessment. This article reflects industry practice as of 2026.