ISO 9001 & AS9100 Certified CNC Drilling Facility
CNC Drilling Services
CNC drilling services separate a functional part from a scrap bin faster than almost any other operation. A hole that is off-center by half a millimeter, oversized by a few microns, or drilled too shallow can ruin an entire assembly.
At Baetro, we deliver precision CNC drilled holes from standard through-holes to gun-drilled deep bores — with instant quotes, free DFM feedback, and no minimum order quantity.
±0.001"
Drilling tolerance
3–7 days
Standard lead time
Free DFM
On every quote
MOQ 1
Prototype to production
CNC Drilling Fundamentals
What Is CNC Drilling?
CNC drilling uses a rotating cutting tool to create round holes in a workpiece. A drill bit spins at a programmed spindle speed while the machine feeds it into the material at a controlled rate.
The difference between a usable hole and a precision bore lies in the details — tool selection, feed rate, coolant pressure, and peck cycle parameters all affect hole quality. For through-holes, the drill exits the far side. For blind holes, the drill stops at a programmed depth, leaving a small conical point.
Rotating Tool Accuracy
Programmed spindle speed and controlled feed rate
Through-Tool Coolant
High-pressure coolant at 10×D depth ratios
Through & Blind Holes
Exit holes and programmed-depth blind holes
Precision Control
Peck cycles optimized for hole quality
Through-Tool Coolant
Critical for chip evacuation in deep holes beyond 10×D
Process Comparison
Drilling vs. Reaming vs. Boring
Not every hole needs the same process. Here is how the three primary hole-making operations compare.
Standard Drilling
CNC Drilling
Fast and cost-effective hole creation for clearance holes, fluid passages, and general through-holes where ±0.05 mm tolerance is acceptable.
- Tolerance: ±0.05 mm (H9–H11)
- Surface finish: 3.2–6.3 µm Ra
- Best for: bolt clearance holes, fluid passages, general through-holes
Precision Reaming
CNC Reaming
Follows drilling to achieve precision fits for dowel pins, bushings, and bearing races where tight tolerances and smooth surface finish are required.
- Tolerance: ±0.01 mm (H7–H8)
- Surface finish: 0.8–1.6 µm Ra
- Best for: dowel pins, bearing seats, press fits
Precision Boring
CNC Boring
Used for large-diameter precision holes where reamers are not practical, or when tolerances tighter than H7 are required for critical alignment bores.
- Tolerance: ±0.005 mm or better (H7 or tighter)
- Surface finish: 0.4–1.6 µm Ra
- Best for: large diameters, critical alignment bores
Procurement confidence
Why Choose Baetro for CNC Drilling?
Engineers and procurement managers choose Baetro for reliable CNC drilling services with fast quoting, deep hole expertise, transparent documentation, and responsive project support.
Engineering-First Partnership
We do not just read your hole callouts and program a cycle. Our engineers analyze your design to optimize hole features for manufacturability — reducing tool changes, minimizing cycle time, and ensuring the specified tolerance is both necessary and achievable. That analysis is included free with every quote.
Transparent Pricing and Lead Times
Upload your CAD file and receive an instant quote with live pricing in under 60 seconds. No hidden setup fees. No tooling charges snuck in after the fact.
- Parts ship in 3–7 days standard
- No minimum order quantity — order 1 piece or 100,000
- Real-time order tracking from setup to delivery
Deep Hole Expertise
Not every shop has gun drilling capability. We do — with high-pressure coolant systems that handle bores to 20×D and beyond. Whether you need a hydraulic cylinder bore, a firearm barrel blank, or a long alignment shaft, our deep hole drilling team has the equipment and experience.
Full Quality Assurance
Every drilled part is inspected for critical dimensions. We use CMM equipment for positional accuracy, bore gauges for hole diameter, and plug gauges for thread verification. Full inspection reports document every measurement. ISO 9001 and AS9100 certified.
Free DFM Feedback
Our engineers review your CAD file and suggest design optimizations that can reduce drilling time, improve hole quality, and lower cost before production begins. Typical DFM feedback identifies unnecessary tight tolerances, suboptimal hole sequences, and accessibility issues.
Fast Lead Times & Documentation
Standard orders ship in 3–7 days, with inspection reports, material certifications, bore diameter verification, and dedicated project manager support included on every shipment.
Material library
Materials We Drill
We drill precision holes in the full range of engineering metals and plastics, with full material certifications and traceability available for every project.
Metals
Aluminum (6061, 7075, 2024) — Easy to drill; excellent chip evacuation; watch for built-up edge on uncoated tools.
Stainless steel (304, 316, 17-4 PH) — Work-hardens rapidly; requires carbide drills and aggressive feeds.
Carbon steel (1018, 1045, 4140) — Good machinability; 4140 requires slower speeds due to hardness.
Titanium (Grade 2, Grade 5) — Low thermal conductivity traps heat; demands coated carbide and rigid setup.
Brass and copper — Excellent machinability; long stringy chips require proper chip breaker geometry.
Plastics
ABS, Nylon, POM — Drill easily with sharp tools; avoid heat buildup that causes melting.
PEEK — Requires carbide tooling; crystalline structure produces abrasive chips.
Polycarbonate — Prone to stress cracking; use sharp drills with adequate coolant.
Acrylic (PMMA) — Maintain low feed rates to prevent cracking and edge chipping.
PVC — Easy to drill; use sharp HSS or carbide tools to avoid fusing.
For material-specific drilling parameters, our engineers reference ASME Y14.5 for geometric dimensioning and tolerancing guidance when interpreting your drawings.
Aluminum
6061, 7075, 2024 alloys for general and aerospace drilling applications.
Stainless Steel
304, 316, 17-4 PH grades for corrosion resistance and high strength drilling.
PEEK
High-performance polymer for demanding thermal, chemical, and biocompatible drilling.
Polycarbonate
High-impact strength requiring careful feed control to prevent cracking.
Engineering data
CNC Drilling Tolerance Guide
The ISO hole-basis system uses "H" codes to define tolerance bands above the nominal diameter. Understanding these grades helps you specify the right tolerance for your application without over-engineering.
| Nominal Ø | H7 (upper) | H8 (upper) | H9 (upper) | H11 (upper) |
|---|---|---|---|---|
| Ø3 mm | +0.010 mm | +0.014 mm | +0.025 mm | +0.060 mm |
| Ø6 mm | +0.012 mm | +0.018 mm | +0.030 mm | +0.075 mm |
| Ø10 mm | +0.015 mm | +0.022 mm | +0.036 mm | +0.090 mm |
| Ø20 mm | +0.021 mm | +0.033 mm | +0.052 mm | +0.130 mm |
| Ø50 mm | +0.025 mm | +0.039 mm | +0.062 mm | +0.160 mm |
Design guidance: Only specify H7 where function requires it — dowel pins, bearings, seals, or sliding fits. Use H9 for general clearance holes and H11 for bolt clearance where generous tolerance is acceptable. Our DFM review flags over-specified tolerances and suggests the appropriate grade for your application.
Capabilities
Our CNC Drilling Capabilities
From standard through-holes to deep gun-drilled bores, Baetro provides CNC drilling services that match the right process to your tolerance, depth, and surface finish requirements.
Standard vs. Gun Drilling
| Parameter | Standard | Gun |
|---|---|---|
| Depth Ratio | 5–10×D | 20×D+ |
| Tolerance | ±0.05 mm | ±0.01 mm |
| Surface (Ra) | 3.2–6.3 µm | 1.6–3.2 µm |
| Coolant | Flood | High-pressure |
| Best For | General holes | Deep bores |
Gun drilling runs coolant pressure up to 150 bar for chip evacuation at extreme depths. Precision tolerances inspected on CMM with full reports.
When to Choose Each Process
- Standard drilling: general through-holes, bolt clearance, fluid passages. Efficient for 0.3–50 mm diameter, depths up to 5–10×D.
- Gun drilling: hydraulic manifolds, firearm barrels, oilfield components. Ideal when depth exceeds 10×D or tolerance tighter than ±0.05 mm.
- Cost impact: gun drilling adds 30–60% over standard, depending on depth, material, and inspection requirements.
- Engineering support: upload CAD files to confirm achievable depth ratios and tolerances for your drilling geometry.
Applications
Industries We Serve with CNC Drilling
CNC drilling is one of the most versatile machining processes, supporting industries with different requirements for tolerance, material selection, surface finish, and inspection documentation.
Aerospace
Aerospace parts demand precise fastener holes, alignment bores, and hydraulic passages. We drill titanium and aluminum structural brackets, stainless steel fluid manifolds, and Inconel engine components. Every hole is inspected for position, diameter, and surface finish. Full material traceability and AS9100 documentation support your certification requirements.
Automotive
Engine blocks, transmission housings, brake calipers, and suspension brackets all require hundreds of drilled holes. Our CNC centers handle high-volume production with consistent hole quality from first part to last. Tapped holes for fluid fittings, counterbored holes for fasteners, and deep bores for pin bushings are standard operations.
Medical Devices
Surgical instruments, implant housings, and diagnostic equipment require small, precise holes in biocompatible materials. We drill PEEK implants, stainless steel instrument shafts, and aluminum device enclosures. Clean room-compatible coolant options and meticulous chip control prevent contamination.
Industrial Equipment
Hydraulic manifolds, valve bodies, pump housings, and mounting plates rely on precisely positioned drilled passages. Our gun drilling capability handles the deep, straight bores common in hydraulic systems. Multi-face machining on 4-axis and 5-axis centers drills holes at compound angles without multiple setups.
Electronics
Heat sinks, enclosures, and connector housings require arrays of small holes with tight positional tolerances. We drill aluminum heat sinks with patterned hole arrays, ABS enclosures for cable glands, and brass terminal blocks with precision through-holes.
Design guidelines
Design Guidelines for Drilled Features
Proper hole design ensures manufacturability, reduces tool breakage, and maintains part integrity. Follow these guidelines for spacing, depth ratios, and tapped holes.
Hole Spacing and Edge Distance
Placing holes too close together or too near an edge invites problems. Minimum center-to-center spacing should be at least 2× the hole diameter to prevent drill walk and wall breakout. Edge distance — the distance from hole center to the nearest part edge — should be at least 1.5× the hole diameter for standard applications, and 2× or more for critical load-bearing features.
Thin walls between holes distort under drilling pressure. If your design requires holes closer than 2× diameter, our engineers may suggest adding material locally or switching to a wire EDM process for the tightest features.
Depth-to-Diameter Ratio
The depth-to-diameter ratio (L/D) determines which drilling approach is appropriate:
| L/D Ratio | Method | Considerations |
|---|---|---|
| < 3×D | Standard drilling | Straightforward; minimal chip concerns |
| 3–10×D | Peck drilling | Periodic retract to break and clear chips |
| > 10×D | Gun drilling | High-pressure coolant; specialized tooling |
Peck drilling is a CNC cycle where the drill periodically retracts to break chips and allow coolant to reach the cutting edge. It is the standard approach for holes deeper than 3×D when gun drilling equipment is not required. Peck depth is typically 1–2×D per peck, depending on material.
Tapped Hole Design
For threaded holes, the drilled pilot hole must be correctly sized. A pilot hole that is too small increases tap torque and breakage risk. Too large, and the thread engagement is weak. Standard tap drill sizes follow the formula:
Tap drill diameter ≈ Major diameter − (1 ÷ threads per inch)
Thread depth should generally be 1.5–2× the major diameter for adequate strength. Deeper threads add cycle time without significant strength improvement. Blind tapped holes require a drill depth deeper than the thread depth to accommodate the tap's lead chamfer.
Design for Manufacturability
DfM Tips from Our Engineers
When you upload a CAD file for a quote, our engineers review your hole features for manufacturability. These suggestions are free and often reduce machining time by 15% or more.
Consolidate Hole Sizes
Reducing the number of different hole diameters minimizes tool changes and setup time, directly lowering per-part cost.
Increase Corner Radii
Adding generous corner radii near holes reduces stress concentration and eliminates the need for specialized corner-breaking tools.
Specify H9 Instead of H7
For non-critical clearance holes, looser H9 tolerances are faster to machine and inspect than tight H7 fits — without sacrificing function.
Add Relief Grooves
Relief grooves at the bottom of blind holes improve chip clearance, prevent drill walking, and extend tool life.
Reorient for Normal Drilling
Reorienting parts so all holes are drilled normal to a single face eliminates angular setups and improves positional accuracy.
FAQ
Frequently Asked Questions
Answers to common questions about CNC drilling tolerances, hole depth, materials, lead times, and quality control.
What tolerance can you hold on drilled holes?
±0.05 mm is our standard drilling tolerance for general holes, equivalent to ISO H9–H11. For precision fits, H7 (±0.01 mm) is achieved with reaming after drilling. Tighter tolerances down to ±0.005 mm are available with boring. Every critical hole is inspected on CMM or with bore gauges, and full inspection reports are included with your shipment.
How deep can you CNC drill?
Standard drilling handles holes up to 5–10× the drill diameter. For deeper holes, we use peck drilling (periodic chip-breaking retracts) up to about 10×D. Beyond that, gun drilling reaches 20×D or deeper with high-pressure through-tool coolant. The exact limit depends on material, diameter, and required straightness.
What is the smallest hole you can drill?
We routinely drill holes down to approximately 0.3 mm in diameter, depending on material and depth. Micro-drilling below 0.5 mm requires specialized spindles and rigid setups. Contact our engineers if your design calls for micro-holes — we will review feasibility based on your specific geometry and material.
Can you tap threads in the same setup as drilling?
Yes. Tapped holes, thread-milled holes, and helical interpolation are all programmed into the same CNC setup as drilling. This eliminates the need to move the part to a separate tapping station, improving positional accuracy between the hole and the thread. We recommend thread milling for large threads, exotic materials, or any application where tap breakage would be costly.
What is peck drilling and when is it used?
Peck drilling is a CNC cycle where the drill periodically retracts from the hole to break chips and allow coolant to reach the cutting edge. It is used for holes deeper than approximately 3× the drill diameter, where standard continuous drilling would cause chip packing, heat buildup, and poor hole quality. Peck depth is typically 1–2×D per peck, depending on material.
How much do CNC drilling services cost?
Drilling is one of the most economical machining operations. The cost depends on hole count, diameter, depth, material, and required tolerance. The fastest way to get an accurate price is to upload your CAD file for an instant quote — you will see live pricing in under 60 seconds. In most cases, drilling adds minimal cost to a machined part.
What is the fastest lead time for drilled parts?
Parts ship in 3–7 days with our standard lead time. There is no minimum order quantity — you can order a single prototype or a full production run. Expedited options are available for urgent projects. Our 24/7 operation allows us to deliver complex parts faster than many domestic shops.
Can you drill hardened steel?
Yes, with the right tooling. We use coated carbide drills and reduced speeds for hardened steels up to approximately 45–50 HRC. For materials harder than that, or for precision holes in fully hardened tooling, we may recommend wire EDM or sinker EDM as a more reliable process. Our engineers will recommend the best approach during DFM review.
Quote-ready manufacturing
Get Precision CNC Drilled Holes — Instantly
CNC drilling is deceptively simple — until a hole is out of tolerance, off-center, or filled with packed chips. At Baetro, we combine the right tooling, the right parameters, and the right inspection to deliver holes that meet your spec every time. From standard clearance holes to gun-drilled deep bores, our engineers review every design for manufacturability before the first chip flies.
Whether you need five prototypes with tapped holes or five thousand production parts with precision bores, upload your CAD file today for an instant quote. See your exact price and lead time in under 60 seconds — no sales calls, no hidden fees, no minimums.
Parts ship in 3–7 days. No minimum order quantity. ISO 9001 & AS9100 certified.
Not ready to upload a file? Contact our engineers to discuss your project, review material options, or get guidance on tolerance selection.