Appearance
A tool presetter does not measure the tool that enters the cut. It measures the tool as it sits in the presetter's spindle. The difference between these two measurements — the effective diameter shift caused by holder runout, clamping force variation, and spindle condition — is the difference between a bore that passes inspection and one that is scrapped. In deep hole drilling, where the tolerance on bore diameter may be H7 (0.025 mm for a 20 mm bore) and the tool itself costs hundreds of dollars, that difference matters.
Why Offline Presetting Matters for Deep Hole Drilling
Deep hole drilling tools — gun drills and BTA drill heads — differ from conventional cutting tools in ways that make offline presetting particularly valuable:
| Factor | Conventional Tool | Deep Hole Drilling Tool |
|---|---|---|
| Tool cost | $20–$200 | $200–$2,000+ |
| Setup time for measurement | 5–10 minutes on-machine | 15–30 minutes on-machine |
| Diameter tolerance | ±0.05 mm typical | ±0.01 mm typical |
| Runout sensitivity | Moderate | Critical — amplified by long shaft |
| Number of critical dimensions | 2–3 (diameter, length) | 5–8 (tip Ø, shank Ø, length, guide pad height, cutting edge radius, coolant hole position) |
Moving tool measurement from the machine to an offline presetter reduces machine downtime, enables more thorough measurement, and provides documented tool data for quality traceability.
Optical Presetter Technology
How Optical Presetters Work
Modern optical presetters use a camera system with telecentric optics to capture a shadow image of the tool, which is analysed by software to extract dimensional data:
| Component | Function | Typical Specification |
|---|---|---|
| Camera | Captures tool image | 1.3–5 MP CMOS or CCD |
| Lens | Telecentric — no perspective error | Bi-telecentric, 20–100× magnification |
| Light source | Backlight for silhouette | LED, collimated |
| Spindle | Rotates tool for 360° measurement | Precision taper, 0.001 mm T.I.R. |
| Granite base | Thermal stability and vibration damping | Natural granite, Class 00 |
| Glass scales | Position measurement | 0.001 mm (1 µm) resolution |
Measurement Capabilities
| Parameter | Principle | Typical Accuracy |
|---|---|---|
| Diameter | Edge detection on shadow image | ±0.002 mm |
| Length | Z-axis scale measurement | ±0.005 mm |
| Runout | 360° rotation, maximum radial deviation | ±0.002 mm |
| Angle | Edge angle detection | ±0.1° |
| Radius | Corner radius fit | ±0.005 mm |
| Step/profile | Multi-point measurement along tool axis | ±0.003 mm |
Key Presetter Specifications for Deep Hole Drilling Tools
| Specification | Entry-Level | Production | Precision |
|---|---|---|---|
| Diameter range | 0–200 mm | 0–300 mm | 0–400 mm |
| Length range | 0–300 mm | 0–500 mm | 0–700 mm |
| Resolution | 0.005 mm | 0.001 mm | 0.0005 mm |
| Repeatability | ±0.005 mm | ±0.002 mm | ±0.001 mm |
| Camera | Standard CMOS | 1.3 MP telecentric | 5 MP bi-telecentric |
| Spindle runout | 0.003 mm T.I.R. | 0.002 mm T.I.R. | 0.001 mm T.I.R. |
For deep hole drilling tools, the spindle runout specification of the presetter is critical. The presetter's own spindle runout adds to the measured tool runout value. A presetter with 0.003 mm spindle runout cannot reliably measure a gun drill that requires 0.005 mm tip runout.
Measuring Gun Drills
Critical Gun Drill Dimensions
| Dimension | Measurement Method | Typical Tolerance |
|---|---|---|
| Tip diameter | Optical — edge detection at the cutting edges | ±0.005 mm |
| Shank diameter | Optical — edge detection at the shank | ±0.010 mm |
| Overall length | Optical — top of shank to tip | ±0.100 mm |
| Guide pad height | Optical — profile measurement of pad OD | ±0.005 mm |
| Cutting edge radius | Optical — edge radius fit | ±0.010 mm |
| Coolant hole position | Optical — centre detection of coolant hole | ±0.050 mm |
| Tip concentricity | 360° rotation, radial measurement at tip | 0.010 mm T.I.R. |
Step-by-Step Gun Drill Measurement Procedure
| Step | Action | Data Recorded |
|---|---|---|
| 1 | Clean the tool shank and presetter spindle taper | — |
| 2 | Mount the gun drill in the presetter spindle | — |
| 3 | Set the Z-axis reference at the tool tip | Length zero |
| 4 | Measure tip diameter at the cutting edge | D_tip |
| 5 | Measure shank diameter at the locating diameter | D_shank |
| 6 | Measure overall length | L_total |
| 7 | Rotate tool 360°, measure tip runout | Runout_TIR |
| 8 | Measure guide pad OD by profiling the pad surface | D_pad |
| 9 | Measure coolant hole position relative to centre | X_cool, Y_cool |
| 10 | Record all data and generate offset report | Complete tool data |
Interpreting Gun Drill Runout Measurements
The runout measured on a presetter is the runout of the tip relative to the shank when the tool is rotated in the presetter spindle. This is a reference value — the actual runout in the machine will differ because of:
| Factor | Effect on Runout | Typical Magnitude |
|---|---|---|
| Presetter spindle runout | Adds to measured value | 0.001–0.003 mm |
| Machine spindle runout | Adds or subtracts (vector sum) | 0.005–0.015 mm |
| Holder runout | Adds to total | 0.005–0.020 mm |
| Clamping force variation | Changes effective runout | 0.002–0.010 mm |
| Coolant pressure (seal compression) | Can shift the tool axially | 0.001–0.005 mm |
Tip: The presetter runout value is most useful as a relative measurement — comparing a tool to its previous measurement to detect wear or damage. For absolute runout control, verify the tool in the machine after clamping, using a dial indicator at the tool tip. The presetter value and the in-machine value typically differ by 0.010–0.030 mm, and the in-machine value is the one that matters for the bore.
Measuring BTA Drill Heads
BTA drill heads have different critical dimensions from gun drills due to their multi-component construction:
| Dimension | Measurement Method | Typical Tolerance |
|---|---|---|
| Head diameter (cutter setting) | Micrometer over the cutting edges | ±0.010 mm |
| Guide pad OD | Micrometer over the guide pads | ±0.005 mm |
| Head concentricity | Dial indicator on the head body in V-blocks | 0.015 mm T.I.R. |
| Insert seating | Feeler gauge under insert | 0.02 mm max gap |
| Chip mouth opening | Optical measurement | ±0.100 mm |
| Thread concentricity | Dial indicator on thread relative to head body | 0.020 mm T.I.R. |
BTA Head Diameter Adjustment
BTA drill heads with adjustable inserts require diameter setting before each use:
| Step | Action | Tool Used |
|---|---|---|
| 1 | Clean the head body and insert seats | Solvent and lint-free cloth |
| 2 | Loosen the insert clamping screws | Torque wrench |
| 3 | Adjust the insert to the nominal diameter | Adjust ball and screw (ISCAR system) |
| 4 | Measure the diameter over the cutting edges | Micrometer (0.001 mm resolution) |
| 5 | Tighten the clamping screws to specified torque | Torque wrench |
| 6 | Re-measure the diameter | Micrometer — verify within ±0.005 mm |
| 7 | Measure guide pad heights relative to head body | Dial indicator |
Data Management and Tool Offsets
From Presetter to CNC
The value of offline presetting is realised when measured tool data is transferred to the CNC machine automatically:
| Transfer Method | Description | Suitability |
|---|---|---|
| Manual entry | Operator reads presetter display and types offsets into CNC | Low — error-prone |
| Barcode/RFID | Presetter prints barcode or writes RFID tag; machine reads when tool is loaded | Medium — reduces errors |
| DNC transfer | Presetter sends offset file to CNC via network | High — automatic |
| Tool management system | Presetter data uploaded to central database; CNC downloads offsets | Best — traceable |
Tool Life Tracking
| Data Point | Source | Purpose |
|---|---|---|
| Measurement timestamp | Presetter | Track tool usage interval |
| Measured diameter | Presetter | Monitor wear rate between regrinds |
| Regrind count | Tool database | Track tool life |
| Runout trend | Presetter (each setup) | Detect holder damage or tool bending |
| Machine spindle load | Machine CNC | Detect cutting edge degradation |
Dimensional Tolerancing for Deep Hole Drilling Tools
| Application | Tool Diameter Tolerance | Bore Tolerance (H7) | Required Presetter Accuracy |
|---|---|---|---|
| General gun drilling | ±0.010 mm | H7 (0.025 mm for 20 mm) | ±0.005 mm |
| Precision gun drilling | ±0.005 mm | H6 (0.013 mm for 20 mm) | ±0.002 mm |
| BTA roughing | ±0.020 mm | H9 | ±0.010 mm |
| BTA finishing | ±0.010 mm | H7 | ±0.005 mm |
Runout Measurement Methods Comparison
| Method | Accuracy | Cost | Best For |
|---|---|---|---|
| Presetter spindle (optical) | ±0.002 mm | $$$$ | Production measurement, documented data |
| Zero spindle (mechanical) | ±0.003 mm | $$$ | Verification of presetter readings |
| V-blocks with dial indicator | ±0.005 mm | $ | Quick check, field verification |
| In-machine indicator | ±0.005 mm | $ | Final verification before cutting |
| Magnetic V-block | ±0.010 mm | $ | Rough check only |
Presetter Selection for Deep Hole Drilling
| Requirement | Why It Matters for Deep Hole Drilling | Minimum Specification |
|---|---|---|
| Spindle accuracy | Gun drills require tip runout measurement to 0.005 mm | 0.002 mm T.I.R. spindle runout |
| Length capacity | BTA drill heads and extended gun drills can exceed 500 mm | 500+ mm Z-axis travel |
| Diameter capacity | BTA heads up to 200 mm diameter | 200+ mm X-axis travel |
| Optical resolution | Guide pad height and cutting edge radius require fine measurement | 1 MP+ telecentric camera |
| Data export | Tool offset data must be transferred to CNC | DNC or network export |
Economic Case for Offline Presetting
| Factor | On-Machine Measurement | Offline Presetting |
|---|---|---|
| Time per tool measurement | 15–30 minutes | 2–5 minutes |
| Machine running during measurement? | No — machine is idle | Yes — machine continues producing |
| Cost per hour (machine + operator) | $100–$200/hr | $0 (no machine downtime) |
| Cost per measurement | $25–$100 | $0 (operator time only, machine running) |
| Tools measured per day (3 shifts) | 5–10 | 30–60+ |
| Annual savings (20 tools/day, $150/hr) | — | $75,000–$150,000 |
A typical deep hole drilling operation measuring 20 tools per day saves between $75,000 and $150,000 annually in machine downtime alone by moving tool measurement to an offline presetter. The presetter investment is typically recovered in 6–12 months for production environments.
Troubleshooting Tool Measurement Problems
| Problem | Likely Cause | Corrective Action |
|---|---|---|
| Measured diameter differs from in-machine diameter | Holder runout adds effective diameter | Measure tool in-machine, create offset correction table |
| Runout reading changes between measurements on the same tool | Dirty spindle taper or holder interface | Clean taper and re-measure |
| Presetter reading drifts over the course of a shift | Thermal expansion of presetter or tool | Allow presetter to warm up for 30 minutes before use |
| Optical edge detection inconsistent | Coolant residue or oil on tool surface | Clean tool before measurement |
| Tool length measurement inconsistent | Tool tip not located at the same axial position | Use consistent reference point — the cutting edge corner |
| BTA head diameter changes after tightening | Insert not seated correctly | Clean insert seat, check for chips under insert |
FAQ
What is a tool presetter and why is it used for deep hole drilling?
A tool presetter is an offline measurement system that measures a cutting tool's dimensions — diameter, length, runout, and geometry — outside the CNC machine. For deep hole drilling, where tools are expensive and tolerances are tight, presetting reduces machine downtime and enables more thorough measurement than is practical on the machine.
What dimensions are critical for gun drill measurement?
The critical dimensions for a gun drill are: tip diameter (determines hole size), shank diameter (determines holder fit), overall length (determines drilling depth), guide pad height (determines bore support), cutting edge radius (determines surface finish), and tip runout (determines bore straightness).
How is runout measured on a gun drill?
Runout is measured by mounting the gun drill in a precision spindle (on a presetter or in a zero spindle), rotating it 360°, and measuring the maximum radial deviation at the tip using an optical camera or dial indicator. The measured value includes the spindle's own runout, so the spindle must be more accurate than the required runout tolerance.
What is the difference between presetter runout and in-machine runout?
Presetter runout measures the tool relative to the presetter's spindle. In-machine runout includes additional error from the machine spindle, toolholder, and clamping force. The in-machine runout is typically 0.010–0.030 mm larger than the presetter reading. Both values should be verified for precision deep hole drilling.
Can a tool presetter measure BTA drill heads?
Yes, but the measurement approach differs from gun drills. BTA drill head diameter is typically measured with a micrometer over the cutting edges after manual adjustment. The presetter can measure head concentricity, guide pad height relative to the head body, and thread concentricity. The overall head diameter is usually verified with a micrometer.
How is presetter data transferred to the CNC machine?
Common transfer methods include manual entry (error-prone), barcode or RFID (medium reliability), and direct DNC network transfer (most reliable). Tool management systems that integrate with the presetter and CNC provide full traceability of tool data.
What accuracy is required for a deep hole drilling presetter?
For general deep hole drilling, a presetter with ±0.005 mm accuracy and 0.002 mm spindle runout is sufficient. For precision applications (H6 bores), ±0.002 mm accuracy and 0.001 mm spindle runout are required. The presetter must be at least 2× more accurate than the tool tolerance being measured.
How often should a tool presetter be calibrated?
Presetters should be calibrated every 12 months for general use, or every 6 months for precision deep hole drilling applications. Calibration should verify the glass scales, spindle runout, and optical edge detection accuracy. A daily verification using a calibration master (a known-diameter pin) is recommended.
What is the economic benefit of offline tool presetting?
The primary benefit is reduced machine downtime. Measuring a deep hole drilling tool on the machine takes 15–30 minutes while the machine is idle. Offline presetting takes 2–5 minutes while the machine continues producing. For an operation measuring 20 tools per day, the annual savings in machine downtime alone is $75,000–$150,000.
What is the difference between static diameter and effective diameter?
Static diameter is the tool diameter measured on a presetter with the tool stationary. Effective diameter is the actual diameter that the tool cuts in the machine, which includes the effect of runout, holder condition, and clamping force. A tool with 0.010 mm static runout and 0.005 mm diameter may cut a bore that is 0.015 mm oversize because the rotating tool sweeps a larger circle than its static diameter.
Conclusion
Tool presetting and offline measurement for deep hole drilling is not a luxury — it is a quality assurance step that directly affects bore diameter control, runout management, and tool life. The three critical measurements are diameter (verified at the cutting edge, not the shank), runout (measured in the presetter and verified in the machine), and guide pad geometry (for BTA heads, pad height must be measured relative to the cutting edges). The economic case is strong: offline presetting converts 15–30 minutes of machine downtime per tool change into 2–5 minutes of productive measurement while the machine continues cutting. The recurring risk is the gap between the presetter reading and the in-machine reality — holder runout, spindle condition, and clamping force all shift the effective diameter. A correction table that maps presetter readings to in-machine measurements for each holder and spindle combination is essential for precision deep hole drilling.