Appearance
A used deep hole drilling machine at 50% of new price is either a bargain or a trap. The difference is determined by what you cannot see: guideway wear, spindle bearing condition, and coolant pump health — all expensive to discover after purchase.
Cost Comparison
| Factor | New Machine | Used Machine |
|---|---|---|
| Purchase price (gun drilling, small) | $100,000 – 300,000 | $40,000 – 150,000 |
| Purchase price (BTA, medium) | $300,000 – 800,000 | $120,000 – 400,000 |
| Purchase price (large BTA) | $800,000 – 1,500,000 | $300,000 – 700,000 |
| Depreciation (first 5 years) | 40–50% | 10–20% |
| Typical retrofit cost | N/A | 10–30% of purchase price |
| Warranty | 12–24 months | As-is or 30–90 days |
Used machines typically sell for 30–60% of the new price depending on age, condition, hours, and manufacturer. The savings must be weighed against retrofit requirements and hidden wear.
New Machine Advantages
- Correct specification: The coolant pump, spindle power, guide bushing configuration, and CNC control are specified for the intended application rather than adapted from a previous owner's requirements
- Latest CNC technology: Siemens 840D or Fanuc 35i with full deep hole cycles, process monitoring, and automation integration. Older controls may lack pecking cycles, real-time torque monitoring, or network connectivity
- Warranty and support: Manufacturer installation, training, and warranty coverage for the first 1–2 years
- Energy efficiency: Newer coolant pump drives (VFD-controlled) and servo motors reduce operating cost
- No hidden wear: All guideways, spindle bearings, seals, and bushings are new
- Financing options: Manufacturers and banks offer better terms for new equipment
Used Machine Advantages
- Lower capital outlay: 40–70% less than new, enabling entry into deep hole drilling capability at lower investment
- Faster delivery: Used machines are available immediately; new machines take 3–12 months for manufacturing
- Known reliability: Established models have documented maintenance requirements and known failure modes
- Depreciation already absorbed: The steepest depreciation (first 5 years) has already occurred
- Upgrade flexibility: A mechanically sound used machine can be retrofitted with a modern CNC control and coolant system at lower total cost than a new machine
Key Inspection Points for Used Machines
Coolant System Condition
The coolant pump is the most expensive single component to replace. Check:
- Pressure stability at the rated setpoint (should hold within 5% without fluctuation)
- Flow rate at the tool (not just at the pump — line losses indicate restrictions)
- Filtration system condition (differential pressure across filters)
- Seal condition (leaks at the rotary union and pressure head)
- Pump motor bearings (noise indicates wear)
Coolant pump replacement costs $20,000–50,000 including installation. If the pump is undersized for your application, factor this into the purchase decision.
Spindle and Guideway Wear
- Spindle radial runout measured at the taper (target < 0.005 mm). Spindle rebuild costs $10,000–30,000
- Guideway wear — check for scoring, uneven lubrication distribution, and backlash in ball screws
- Linear positioning accuracy measured with laser interferometer (target ±0.005 mm per metre)
- Test the full axis travel for smoothness and binding
Guide Bushing and Tool Support
- Guide bushing inner diameter — clearance should not exceed 0.05 mm on the drill diameter. Replacement costs $500–2,000 per bushing
- Whip guide alignment with the spindle axis
- Steady rest condition and clamping force consistency
Electrical and Control System
- CNC control age and spare parts availability (controls older than 15 years may have obsolete components)
- Working condition of all sensors (coolant pressure, temperature, position)
- Emergency stop and safety interlock functionality
- Drive amplifier condition (older analog drives are harder to service)
Retrofit Cost Assessment
| Retrofit Item | Typical Cost | Notes |
|---|---|---|
| Coolant pump upgrade | $20,000 – 50,000 | Required if undersized for your application |
| CNC control retrofit | $30,000 – 80,000 | Includes new control, drives, and programming |
| Spindle rebuild | $10,000 – 30,000 | Bearing replacement and alignment |
| Guide bushing replacement | $500 – 2,000 each | Consumable item |
| Guideway reconditioning | $15,000 – 40,000 | Scraping or grinding worn surfaces |
| Coolant filtration upgrade | $5,000 – 15,000 | Required if filtration is inadequate |
| Rotary union replacement | $2,000 – 8,000 | High-wear item on high-pressure systems |
Total retrofit costs typically add 10–30% to the used purchase price. Machines requiring more than 30% in retrofits are usually better replaced with new equipment.
Three Red Flags for Used Machines
No maintenance records. A deep hole drilling machine without service logs has hidden wear that will surface as unexpected downtime.
Coolant system leaks. Multiple leaks at seals, hoses, and the rotary union indicate systemic neglect. Coolant system repair costs add up quickly.
Guide bushing clearance > 0.05 mm. Excessive clearance causes bell mouth and straightness problems that cannot be fixed by adjustment alone. It also indicates the previous owner ran the machine beyond recommended bushing replacement intervals.
Decision Framework
| Condition | Choose New | Choose Used |
|---|---|---|
| Budget available | Full | 40–60% of new price |
| Required delivery | 3–12 months wait | Immediate |
| CNC technology requirement | Latest (Siemens 840D / Fanuc 35i) | Older control acceptable |
| Coolant pressure requirement | High (> 100 bar) | Standard (< 60 bar) |
| Required spindle power | > 50 kW | < 30 kW |
| Automation integration | Full (robot, gantry) | Manual operation acceptable |
| In-house maintenance capability | Limited | Strong |
| Financing available | Yes | Limited |
| Risk tolerance | Low | Higher |
FAQ
How much does a new deep hole drilling machine cost?
$100,000–300,000 for small gun drilling machines, $300,000–800,000 for medium BTA machines, and $800,000–1,500,000 for large BTA systems.
What is a used deep hole drilling machine worth?
30–60% of the new price depending on age, hours, condition, and manufacturer. A well-maintained 10-year-old machine from a premium manufacturer (TBT, UNISIG, Mollart) retains higher value.
What is the most expensive retrofit on a used deep hole drilling machine?
CNC control retrofit ($30,000–80,000) is typically the most expensive, followed by coolant pump upgrade ($20,000–50,000) and spindle rebuild ($10,000–30,000).
How do I inspect guide bushing wear on a used machine?
Measure the inner diameter with a bore gauge and compare to the original specification. Clearance exceeding 0.05 mm on the drill diameter requires replacement. Also check for ovality and scoring.
Is a used deep hole drilling machine with worn guideways worth buying?
Only if the price accounts for guideway reconditioning ($15,000–40,000). Worn guideways affect straightness and cannot be ignored — they will produce progressively worse holes.
Can I retrofit a modern CNC control onto an old deep hole drilling machine?
Yes. Siemens 828D/840D and Fanuc Oi controls can be retrofitted. The total cost ($30,000–80,000) is typically 50–60% of the cost difference between a used and new machine.
What should I test during a used machine demonstration?
Drill a test hole in your own workpiece material. Measure straightness, diameter tolerance, and surface finish. Run the machine at full depth with the coolant system at operating pressure.
How long does a deep hole drilling machine last?
With proper maintenance, 20–30 years. The mechanical structure (bed, column, guideways) lasts the longest. Coolant pumps, spindles, and CNC controls are replaced or rebuilt during the machine's life.
Are used German deep hole drilling machines better than used Asian machines?
German machines (TBT, Mollart) typically have heavier cast-iron construction and longer service life, justifying a higher used price. Asian machines (Precihole, Guanlu) offer lower entry cost but may have shorter guideway life.
What is the depreciation curve for deep hole drilling machines?
Steepest in the first 5 years (40–50% depreciation), then gradual to 10–15% of new value at 20+ years. A well-maintained premium machine at 10 years is typically valued at 25–35% of new.
Conclusion
New deep hole drilling machines provide correct specification, warranty, latest CNC technology, and no hidden wear. Used machines provide 40–70% cost savings but carry risks that require thorough pre-purchase inspection. The five critical inspection points are coolant pump condition, spindle bearing wear, guideway condition, guide bushing clearance, and CNC control obsolescence. Retrofit costs of 10–30% of the purchase price should be budgeted. The decision framework centres on budget, technology requirements, coolant pressure needs, and in-house maintenance capability. A machine needing more than 30% in retrofits is usually better replaced with new.