The CNC control is the interface between the operator and the machine. For deep hole drilling, the control needs specific features that general machining centers do not always have. I have worked with FANUC, Siemens, and Heidenhain controls on deep hole drilling machines, and each has strengths and weaknesses depending on the application and the operator skill level.
Core Features Required for Deep Hole Drilling
Before comparing specific control brands, I need to define the features that matter for deep hole drilling. I have developed a checklist based on years of running production jobs on different controls.
| Feature | Why It Matters | FANUC | Siemens | Heidenhain |
|---|---|---|---|---|
| Peck cycle with variable depth | Allows optimized peck depth based on chip load | Yes (G73/G83 extended) | Yes (CYCLE83) | Yes (CYCL CALL) |
| Spindle load monitoring | Detects tool wear and chip packing | Yes (macro calls) | Yes (integrated) | Yes (integrated) |
| Tool life management | Tracks number of holes per tool | Yes (tool data) | Yes (tool mgmt) | Yes (TOOL CALL) |
| Custom macro programming | Allows custom deep hole cycles | Yes (macro B) | Yes (high-level) | Yes (Q parameters) |
| Conversational programming | Easier for non-G-code operators | Limited | ShopTurn | Best in class |
| Coolant pressure monitoring | Alerts on pressure drops | Via PLC | Via PLC | Via PLC |
| Data output to SPC | Trends for quality tracking | Yes (via RS-232) | Yes (via network) | Yes (via network) |
| Programmable retract distance | Short retract chip break vs full retract | No (machine parameter) | Yes (VARI parameter) | Yes (Q256, Q257, Q258) |
| Progressive peck depth | Reduce peck depth as hole deepens | No (constant Q) | Yes (DAM, FDPR) | Yes (Q212 decrement) |
| Dwell at hole bottom | Ensures chip break before retract | No (P word limited) | Yes (DTB) | Yes (Q211) |
The three essential features for deep hole drilling are programmable peck cycle with variable depth, spindle load monitoring with configurable alarm thresholds, and tool life management that tracks holes per tool rather than just cutting time. The additional features like progressive peck depth and programmable chip-break retract distance become important for difficult materials or deep holes beyond 100x diameter.
FANUC Controls: The Industry Standard
FANUC is the most common control on deep hole drilling machines. I would estimate that 60 to 70 percent of the machines I have worked with had FANUC controls. The reliability is excellent and the parts availability is unmatched. If a FANUC control fails, I can get a replacement power supply or I/O board within 24 hours from multiple distributors.
FANUC offers reliable peck cycle programming through G73 and G83 codes with extended parameters. G73 is the high-speed peck drilling cycle that uses a short retract between pecks for chip breaking. G83 is the deep hole peck drilling cycle that fully retracts the tool to the R-plane between each peck. The retract distance for G73 is set as a machine parameter, not programmable in the G-code. This limitation means I cannot fine-tune the chip-break distance per operation without changing the machine setting.
The custom macro programming capability (Macro B) allows me to write specialized deep hole drilling cycles that include spindle load monitoring, auto-retract on load spikes, and coolant pressure checking between pecks.
The spindle load monitoring on FANUC requires some macro programming to implement well. I have written macros that read the spindle load during the cut and compare it to a programmed threshold. If the load exceeds the threshold, the macro triggers a peck retract to clear the chips. This type of adaptive control has prevented many tool breakages.
The main limitation of FANUC is the conversational programming. The FANUC Manual Guide i is functional but not as intuitive as Siemens ShopTurn or Heidenhain TNC. For shops that hire operators with G-code experience, this is not an issue.
Siemens Controls: ShopTurn and 840D
Siemens controls are common on European-built deep hole drilling machines. I have worked with Siemens 840D and 828D controls. The ShopTurn programming interface is intuitive for operators who are not comfortable with standard G-code. The programmer cycles through a series of on-screen forms that prompt for the cutting parameters.
Siemens CYCLE83 is the deep hole peck drilling cycle. Its key advantage over FANUC G73/G83 is the flexibility. Parameters include FDEP (first drilling depth), DAM (decrement per peck — the amount each peck reduces), FDPR (final peck depth), DTB (dwell time at bottom), DTS (dwell time at top for chip break), FRF (feed rate factor for the first peck), and VARI (defines full retract versus chip break). The VARI parameter lets me choose between full retract and short retract chip breaking, and the retract distance is programmable per-call — not a machine parameter like on FANUC.
Siemens Cycle800 provides angled drilling support, which is useful for drilling coolant holes in shafts at an angle. The spindle load monitoring on Siemens is well integrated into the control software. I have found the Siemens load monitoring to require less custom programming compared to FANUC.
The Siemens tool management system is more sophisticated than FANUC in my experience. It tracks tool usage by time, number of holes, or cutting distance, and can trigger tool change events that are integrated with the machine tool changer.
The downside of Siemens is the learning curve for the control architecture. The Siemens control has multiple levels of access and configuration that can be confusing for operators who only know FANUC. The parts supply for Siemens is not as fast as FANUC in North America, which means longer downtime if a control module fails.
Heidenhain Controls: Conversational Excellence
Heidenhain controls offer the most intuitive conversational programming I have used. The TNC language is close to English and easy for new operators to learn. A competent operator can write a deep hole drilling program in the TNC conversational mode without ever typing a G-code.
Heidenhain Cycle 205 (UNIVERSAL PECKING) is the most parameter-rich peck cycle of the three controls. Parameters include Q200 (set-up clearance), Q201 (depth), Q202 (plunging depth — first peck), Q212 (decrement — reduction per peck), Q205 (minimum plunging depth), Q258 (upper advance stop distance — chip break retract), Q259 (lower advance stop distance), Q257 (depth for chip breaking), Q256 (distance for chip breaking — the short retract amount), and Q395 (depth reference, tip versus cylindrical portion). This level of control is unmatched for complex deep hole operations.
Heidenhain controls are less common on deep hole drilling machines. I have only seen them on European machines from specific builders. The TNC control handles peck cycles well with the CYCL CALL function, and the Q parameter programming provides flexibility similar to FANUC Macro B.
The Heidenhain spindle load monitoring is displayed graphically in real time. The operator can see the load trend over the last several seconds, which helps in detecting gradual load increases from tool wear.
The main limitation of Heidenhain is the smaller distributor network. Getting parts and service for Heidenhain controls takes longer than FANUC in most regions. For a production shop that needs fast support, this is a significant consideration.
Programming Considerations by Control
Each control requires a different programming approach for deep hole drilling cycles. Here is a side-by-side comparison:
| Aspect | FANUC | Siemens | Heidenhain |
|---|---|---|---|
| Basic peck cycle | G83 Z- Q_ R_ F_ | CYCLE83(…) with parameters | CYCL DEF 205 + Q parameters |
| Retract behavior | Machine parameter (fixed) | VARI=0 full retract, VARI=1 chip break | Q256/Q257/Q258 programmable |
| Progressive peck | Not available | DAM (decrement) + FDPR (final depth) | Q212 (decrement) + Q205 (minimum) |
| Dwell | Not standard | DTB (bottom), DTS (top) | Q211 (bottom) |
| Feed rate control | Single F word | FRF (factor for first peck) | Q206 (plunging feed), Q253 (pre-position) |
| Spindle load monitoring | Requires Macro B programming | Integrated in control software | Graphical real-time display |
For standard production work, all three controls perform adequately. The differences matter most when drilling difficult materials like Inconel or titanium, where progressive peck depths and programmable chip-break distances reduce tool wear significantly.
Retrofit Options
Older deep hole drilling machines with outdated controls can be retrofitted with modern CNC systems. I have done retrofits on three machines over the past ten years. The most common retrofit path is to replace a dead Fanuc 0-series or Siemens 810 with a newer Fanuc 0i-F or Siemens 828D.
Retrofit considerations:
- The PLC program must be rewritten for the new control, which is the most time-consuming part of the retrofit.
- Existing servo motors and drives from the old control can sometimes be reused if the new control supports the same feedback protocol.
- The coolant pressure monitoring and spindle interlock circuits must be re-integrated with the new control.
- Retrofit cost typically ranges from $15,000 to $40,000 depending on the control and the scope of rework required.
PC-based retrofits using LinuxCNC or other open-source platforms are available but I do not recommend them for deep hole drilling. The real-time control requirements for peck cycles and spindle load monitoring are better served by industrial controls.
Practical Recommendation
For deep hole drilling, I look for three features in a control regardless of brand. The control must support peck cycle programming with programmable peck depth and retract distance. It must have spindle load monitoring with configurable alarm and stop thresholds. It must have tool life management that tracks the number of holes per tool.
All three major controls provide these features adequately. The choice comes down to operator preference and local support availability. I would not choose a machine based on the control alone if the control supports these three features.
For a shop with existing FANUC experience, I recommend staying with FANUC. For a shop that hires operators with varied backgrounds, Siemens or Heidenhain with conversational programming reduces training time.
For more on maintaining and troubleshooting CNC controls, see my guide on troubleshooting CNC control problems.
Key Takeaways
- The three essential control features for deep hole drilling are variable-depth peck cycles, spindle load monitoring with configurable thresholds, and tool life management tracking holes per tool.
- FANUC controls dominate the market with 60-70 percent share, offering excellent reliability but requiring Macro B programming for advanced features like spindle load monitoring.
- FANUC G73/G83 retract distance is a fixed machine parameter, not programmable per-cycle — a limitation for difficult materials.
- Siemens CYCLE83 offers progressive peck depths, dwell at both bottom and top, and feed rate reduction factors — all programmable per-call.
- Heidenhain Cycle 205 is the most parameter-rich peck cycle available, with programmable chip-break distances, decrement control, and depth reference options.
- For simple production drilling, FANUC works well. For difficult materials requiring fine-tuned chip control, Siemens or Heidenhain offer more flexibility.
- Retrofit cost for a dead control is $15,000-$40,000; plan for PLC program rewrite as the largest cost item.
- I recommend choosing the machine based on its mechanical quality and coolant system capability first, and the control second — all three major controls can handle deep hole drilling adequately.
- For shops with existing FANUC experience, staying with FANUC minimizes training time; for mixed-skill shops, Siemens or Heidenhain conversational interfaces reduce the learning curve.
- For maintenance and troubleshooting, see troubleshooting CNC control problems.