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If you need ten deep holes drilled this month and a hundred next month, buying a $300,000 BTA machine is probably the wrong answer. Contract deep hole drilling services offer immediate access to specialized equipment, skilled operators, and quality certifications — without the capital investment, training burden, or utilization risk.
When to Use Contract Deep Hole Drilling
| Situation | In-House | Contract Service |
|---|---|---|
| Monthly volume < 500 holes | Consider contract | Recommended |
| Monthly volume 500–2,000 holes | Break-even analysis needed | Break-even analysis needed |
| Monthly volume > 2,000 holes | Recommended | Consider for overflow |
| Occasional deep hole requirement (1–5 jobs/year) | Not economical | Recommended |
| Specialized material (Inconel, titanium) | High learning curve | Recommended |
| Prototype or R&D work | Flexible | Cost-effective for limited quantities |
| Production with proprietary process | May require in-house | Risk of IP exposure |
| Tight delivery schedule | Lead time for machine purchase | Immediate capacity |
Global Contract Service Providers
Europe
Mollart Engineering (UK)
Founded over 80 years ago, Mollart is one of the most established names in contract deep hole drilling.
| Capability | Specification |
|---|---|
| Component weight | Up to 20 tonnes |
| Diameter range | 10–1,600 mm |
| Length capacity | 10–6,000 mm |
| Methods | Gun drilling, BTA, STS, trepanning |
| Additional services | CNC machining, fabrication, assembly, roller burnishing, ISO6 cleanroom |
| Certification | ISO 9001:2015 |
| Tooling | Manufactures gun drills under license from Botek (Germany) |
| Locations | Chessington (Surrey) and Resolven (South Wales) |
| US presence | Mollart America — sales, engineering, and service |
Mollart serves aerospace, defense, automotive, nuclear, medical, oil and gas, and telecommunications industries.
Perfect Bore Manufacturing (UK)
Specialist subcontract deep hole driller focused on high-precision aerospace work.
| Capability | Specification |
|---|---|
| Core services | Gun drilling, deep hole boring, honing, superfinishing, CNC turning, CNC cylindrical grinding |
| Quality | AS9100:2016 (aerospace), ISO 14001:2015 |
| Industry approvals | SC21, Fit For Nuclear (F4N) |
| Key clients | Airbus, Boeing, BAE Systems, Rolls-Royce, GE Aviation, Moog |
| Industries | Aerospace, oil and gas, defense, nuclear, medical, automotive, power generation |
Perfect Bore is among the most highly certified contract deep hole drilling services, making them a strong choice for aerospace and defense applications requiring full traceability and process control.
Hone-All Precision (UK)
Specialist in deep hole boring, gun drilling, and honing for long and thin-wall tubular components.
| Capability | Specification |
|---|---|
| Core services | Deep hole boring, gun drilling, honing, CNC turning |
| Specialty | Thin-wall tubing, long tubular components |
| Industries | Aerospace, oil and gas, pharmaceutical, medical, automotive, motorsport, defense |
| Quote philosophy | Fully bespoke — no standard per-hole pricing |
Hone-All publishes detailed guidance on pricing and quoting, making them a particularly transparent option for buyers new to deep hole drilling contract services.
Accura Geneva (UK)
| Capability | Specification |
|---|---|
| Core services | Gun drilling, deep hole boring, CNC machining, offset boring |
| Industries | Aerospace, motorsport, oil and gas, diesel engine |
| Certification | ISO 9001:2008, working toward AS9100 |
| Approvals | Cobham, Schlumberger, Messier-Dowty, GE Aviation |
North America
Hunting Dearborn (USA — Fryeburg, Maine)
| Capability | Specification |
|---|---|
| Diameter range | 0.02–762 mm |
| Length capacity | 450 mm–12,000 mm |
| Methods | Gun drilling, BTA/STS drilling, trepanning, pull boring, bottle boring, contour boring, skiving/reaming, bore burnishing, honing, precision grinding |
| Certification | ISO 9001:2015, AS9100D, ITAR registered, DDTC Licensed |
| Industries | Aerospace, defense, oil and gas, power generation, nuclear, commercial equipment, chemical/refining, transportation |
| Global reach | Serves North America, Europe, and Asia |
Hunting Dearborn offers the widest diameter range (0.02–762 mm) of any contract deep hole drilling service identified, making them a strong choice for both micro-drilling and large-bore applications.
Asia
Dedicated Asian deep hole drilling contract services exist but are less documented in English-language sources. Asian manufacturers of deep hole drilling machines (HTT, Precihole, Dalian Jori, TIBO) often provide contract drilling services alongside machine sales. Regional machining centres in China, Taiwan, India, and South Korea also offer gun drilling and BTA services.
Tip: For Asian contract services, search industry-specific B2B platforms and local language directories. Many Asian manufacturers offer contract drilling at 30–50% lower rates than European or North American providers, but certification levels, quality control, and communication should be carefully evaluated.
Pricing Models
Why Deep Hole Drilling Has No Standard Per-Hole Price
Deep hole drilling contract services universally quote on a bespoke basis. According to Hone-All Precision:
"If you seek out five quotes for deep hole drilling, boring and honing, the likelihood is you will receive five wildly different figures."
This variation arises from different assumptions about:
| Factor | Impact on Price |
|---|---|
| Drill wander allowance | 1 mm/m standard — tighter adds cost |
| Material machinability | Inconel costs 3–5× more than 4140 steel |
| Setup complexity | Multi-diameter or offset bores add setup time |
| Tolerance band | ±0.1 mm is standard; ±0.025 mm doubles cost |
| Surface finish | Honing from Ra 1.6 to Ra 0.4 adds significant cost |
| Quantity | Setup amortized over batch size |
| Certification | Aerospace (AS9100) traceability adds 10–20% |
Pricing Factors
| Factor | Standard | Premium | Cost Multiplier |
|---|---|---|---|
| Hole diameter | 6–50 mm | < 3 mm or > 100 mm | 1.5–3× |
| Depth / L/D ratio | < 50× diameter | > 100× diameter | 1.5–4× |
| Material | 4140/1045 steel | Inconel, titanium, 304 SS | 2–5× |
| Tolerance | ±0.1 mm | ±0.025 mm | 1.5–2.5× |
| Straightness | 1 mm/m | 0.1 mm/m | 2–4× |
| Surface finish | Ra 1.6 μm | Ra 0.4 μm | 1.5–3× |
| Certification | ISO 9001 | AS9100 / NADCAP | 1.2–1.5× |
| Quantity | 500+ pieces | 1–10 pieces | 3–10× (per piece) |
Contract Models
| Model | Description | Best For |
|---|---|---|
| Single job order | One-time quote for specific quantity | Prototypes, occasional work |
| Annual supply agreement | Fixed pricing for forecasted volume | Recurring production |
| Framework contract | Pre-agreed rates with call-off | Variable volume, known specs |
| Machine hour rate | Price per hour of machine time | Long runs, simple geometries |
| Per-piece price | Fixed price per completed part | High volume, stable specs |
RFQ Best Practices
Information to Include in Every RFQ
A complete RFQ eliminates back-and-forth and produces comparable quotes:
- Material specification — grade, hardness, heat treatment condition
- Outside diameter or envelope — for fixturing and wall thickness assessment
- Hole diameter — finished size and tolerance
- Overall length — ensure within machine stroke capacity
- Bore type — through-hole or blind; blind bore bottom condition (flat, 60°, 120°, radius)
- Depth tolerance — for blind bores
- Bore tolerance — standard ±0.1 mm or tighter
- Surface finish — Ra value; specify if as-drilled or honed
- Straightness / TIR — standard 1 mm/m or tighter
- Quantity — current batch and annual volume
- Quality standard — ISO 9001, AS9100, or customer-specific
- Delivery requirement — lead time expectation
- Drawing — GD&T specification including all datums
Warning: Incomplete RFQs produce incomparable quotes. One supplier may quote to ±0.1 mm tolerance while another assumes ±0.05 mm — the second quote will be higher, but not because they are more expensive for the same work. Always specify tolerance and straightness requirements explicitly.
Red Flags When Evaluating Quotes
| Red Flag | Risk |
|---|---|
| Quote significantly below market | Corners cut on setup, inspection, or material handling |
| No questions about tolerances | Assumes standard tolerances that may not match your needs |
| Cannot provide certification copies | May not hold claimed certifications |
| No request for full drawing | Missing critical details that cause change orders |
| Vague about drill wander allowance | May reject parts with acceptable-for-industry straightness |
| Cannot provide references | Limited experience with similar work |
Quality Certifications
| Certification | Relevance | Required For |
|---|---|---|
| ISO 9001:2015 | General quality management | Most commercial applications |
| AS9100D | Aerospace quality standard | Aerospace, defense, space |
| NADCAP | Special process certification | Aerospace heat treat, surface finishing, welding |
| ISO 14001 | Environmental management | Many European OEM requirements |
| ITAR registration | US defense export control | Defense, military components |
| Fit For Nuclear (F4N) | UK nuclear supply chain | Nuclear power applications |
Quality and Tolerance Expectations
| Parameter | Standard Contract Service | Premium Contract Service |
|---|---|---|
| Diameter tolerance (drilled) | ±0.05–0.10 mm | ±0.025–0.050 mm |
| Diameter tolerance (honed) | ±0.010–0.025 mm | ±0.005–0.010 mm |
| Surface finish (drilled) | Ra 1.6–3.2 μm | Ra 0.8–1.6 μm |
| Surface finish (honed) | Ra 0.4–0.8 μm | Ra 0.1–0.4 μm |
| Straightness | 1 mm/m | 0.1–0.5 mm/m |
| Roundness | 0.02–0.05 mm | 0.005–0.020 mm |
FAQ
When should I use a contract deep hole drilling service instead of buying a machine?
When monthly volume is below 500 holes, the work is occasional (1–5 jobs/year), the material is exotic requiring specialized tooling, or immediate delivery is needed. Contract services avoid the $50,000–1,000,000 machine investment.
How much does contract deep hole drilling cost?
Pricing is always bespoke, but typical ranges: simple gun drilling in steel: $5–50 per hole depending on diameter and depth; complex BTA drilling in stainless: $100–1,000 per hole. Request quotes with complete specifications.
What information do I need to get a quote?
Material, hole diameter, length, bore type (through/blind), tolerance, surface finish, straightness requirement, quantity, quality standard, and a drawing with GD&T.
Which contract service is best for aerospace work?
Perfect Bore Manufacturing (AS9100:2016, Airbus/Boeing/Rolls-Royce approved) and Hunting Dearborn (AS9100D, ITAR registered) are both well-qualified for aerospace deep hole drilling.
Which service has the largest diameter capacity?
Mollart Engineering handles diameters up to 1,600 mm. Hunting Dearborn covers 0.02–762 mm. For very large bores, Mollart has the edge.
Can contract services handle small-diameter gun drilling?
Hunting Dearborn offers diameters as small as 0.02 mm. Most services cover 2–40 mm gun drilling comfortably.
What certifications should I look for?
ISO 9001:2015 for general quality. AS9100D for aerospace. NADCAP for special processes. ITAR registration for US defense work.
Are there Asian deep hole drilling contract services?
Yes, but they are less documented in English sources. Asian machine manufacturers (HTT, Precihole) often offer contract services. Rates are typically 30–50% lower than European or North American providers.
What is the standard straightness tolerance for contract deep hole drilling?
Industry standard is 1 mm per meter of depth (approximately 0.001" per inch). Tighter straightness is possible but increases cost.
How do I compare quotes from different providers?
Ensure all quotes are based on identical specifications — tolerance, straightness, surface finish, material, and certification. Differences in any of these assumptions will produce different prices. Ask each supplier to quote to the same tolerance band.
Conclusion
Contract deep hole drilling services provide immediate access to specialized equipment and expertise without capital investment. Leading global providers — Mollart Engineering (10–1,600 mm, 20 tonnes), Hunting Dearborn (0.02–762 mm, AS9100D), Perfect Bore (aerospace-approved), and Hone-All (thin-wall specialists) — offer distinct capabilities suited to different applications. Pricing is always bespoke, determined by material, dimensions, tolerances, quantity, and certification requirements. The key to successful contracting is providing complete, unambiguous specifications in the RFQ and evaluating quotes on the same basis. For low-to-medium volume production, prototype work, and specialized materials, contract services deliver better economics than machine ownership.