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Leitech: The Industry Standard for Thread Depth Gaging

Leitech COMBI gages ** Simultaneously Check Thread Size and Depth

Leitech COMBI gages ** Simultaneously Check Thread Size and Depth

Leitech COMBI gages ** Simultaneously Check Thread Size and Depth

Leitech COMBI gages ** Simultaneously Check Thread Size and Depth

Leitech COMBI gages ** Simultaneously Check Thread Size and Depth

Leitech COMBI gages ** Simultaneously Check Thread Size and Depth

Collage of the best quality control tools to use for thread depth inspection: Leitech COMBI gages

 

Leitech US

1134 N. 9th St.

Suite 280

Milwaukee, WI 53233


Phone: 414-333-6310


leitech.com



Request Quote or More info

the Global Standard for Thread Depth Quality Control

Beyond Estimation: Absolute Metrological Certainty

In high-precision manufacturing, the difference between a pass and a fail often comes down to the reliability of your thread depth data. 


Whether you are navigating the strict requirements of Aerospace, Automotive, or Medical production, subjective estimation isn't an option.


The Leitech COMBI system is engineered to replace 'eyeballing' with traceable numerical truth—streamlining your inspection process and future-proofing your quality lab.

Standard Leitech COMBI gage with telescoping sleeve for fast, reliable thread depth control.

STANDARD Combi: The Original Workhorse

HI-RESOLUTION Combi: Precision and Accessibility

HI-RESOLUTION Combi: Precision and Accessibility


  • The Problem:  Traditional gaging requires multiple tools or unreliable "turn counting" to estimate depth.


  • The Leitech Solution:  One Stanardgage measures any depth within its range, providing the actual numerical value needed to adjust CNC offsets. .


  • Impact:   Replaces entire sets of fixed-depth gages. Whether inspecting one part with multi


  • The Problem:  Traditional gaging requires multiple tools or unreliable "turn counting" to estimate depth.


  • The Leitech Solution:  One Stanardgage measures any depth within its range, providing the actual numerical value needed to adjust CNC offsets. .


  • Impact:   Replaces entire sets of fixed-depth gages. Whether inspecting one part with multiple depths or several parts with the same thread size, one tool measures them all directly.

Leitech Hi-Resolution COMBI thread depth gage for holes with tighter depth tolerances: 0.1mm/ .005"

HI-RESOLUTION Combi: Precision and Accessibility

HI-RESOLUTION Combi: Precision and Accessibility

HI-RESOLUTION Combi: Precision and Accessibility

 

  • The Problem: Need to measure to tighter depth tolrance or in confined spaces that force operators to "guess" depth readings.
  • The Leitech Solution: Offering a higher 0.1mm / 0.005" resolution and a unique locking device, this tool "freezes" the actual value for accurate reading outside the part.
  • Impact:  The Hi-Res COMBI locking device al

 

  • The Problem: Need to measure to tighter depth tolrance or in confined spaces that force operators to "guess" depth readings.
  • The Leitech Solution: Offering a higher 0.1mm / 0.005" resolution and a unique locking device, this tool "freezes" the actual value for accurate reading outside the part.
  • Impact:  The Hi-Res COMBI locking device allows for "remote readings," meaning you can still capture the measurement in a difficult-to-reach area and read it once the tool is removed.

Leitech Digi-COMBI Digital Thread Depth Gage with LCD display and wireless data transfer.

DIGI-Combi: Digital Accuracy & SPC

HI-RESOLUTION Combi: Precision and Accessibility

DMG-Combi: The Ultimate in Automated Consistency

 

  • The Problem:  Manual data entry slows down the shop floor and introduces costly transcription errors in the Gage Lab. 


  • The Leitech Solution:  Features an ultra-precise LCD readout with RS232 output for instant data collection. 


  • Impact:  Designed for modern Industry 4.0 shops, the Digi-COMBI facilitates immediate digital quality logging and

 

  • The Problem:  Manual data entry slows down the shop floor and introduces costly transcription errors in the Gage Lab. 


  • The Leitech Solution:  Features an ultra-precise LCD readout with RS232 output for instant data collection. 


  • Impact:  Designed for modern Industry 4.0 shops, the Digi-COMBI facilitates immediate digital quality logging and wireless data transfer integrates with SPIC systems to eliminate manual entry errors.

Leitech DMG Digital Motorized Thread Depth Gage, with standardized torque, automation integration.

DMG-Combi: The Ultimate in Automated Consistency

HI-RESOLUTION Combi: Precision and Accessibility

DMG-Combi: The Ultimate in Automated Consistency

 

  • The Problem:  Need to automate thread depth gaging; or  "Operator feel" and torque variability lead to inconsistent readings across different shifts or automated cells.


  • The Leitech Solution:  This digital motorized model eliminates operator variability by ensuring standardized torque for every measurement.
  • Impact:  Engineered for maxim

 

  • The Problem:  Need to automate thread depth gaging; or  "Operator feel" and torque variability lead to inconsistent readings across different shifts or automated cells.


  • The Leitech Solution:  This digital motorized model eliminates operator variability by ensuring standardized torque for every measurement.
  • Impact:  Engineered for maximum throughput in automated environments, the DMG-COMBI model provides the ultimate consistency required for high-volume quality logging.

Leitech : how to measure thread depth

Hi-Res COMBI Gage

 BEST FOR: Tighter tolerances, confined access, difficult-to-read locations

 

  • 5x greater resolution for precision applications
  • Resolution: 0.1 mm (0.005")
  • Unique locking device to freeze the depth reading
  • Perfect for dark, confined, or difficult-to-access blind holes
  • Allows reading capture before removing gage from part

Digital DIGI-COMBI Gage

BEST FOR: Modern manufacturing, SPC data collection


  • Eliminates manual reading errors with instant digital display
  • Resolution: 0.01 mm (0.0005") ultra-precise LCD readout
  • Instant inch/metric toggle for multi-standard environments
  • RS232 data output for direct SPC system integration
  • Zero transcription errors—measurements flow directly to quality software


DMG Digital Motorized COMBI Gage

  Best For: High-volume automation and eliminating operator variability to maximize throughput. 

 

  • Standardized Torque: Motorized handle ensures identical measurement force every time, completely eliminating "operator feel" variability.
  • Digital Precision: High-resolution output with variable speed settings optimized for different material types.
  • Industry 4.0 Ready: Supports wireless data transmission for seamless integration into robotic inspection cells.
  • GR&R Optimization: Engineered for maximum repeatability and reproducibility in 24/7 production environments.

The Machinist’s Guide to Precision Thread Depth Inspection

 

In the world of high-precision machining—whether you are in Aerospace, Medical, Defense, Energy or Automotive—"good enough" doesn't pass the audit. When a part print calls for a specific thread depth, the method you choose to inspect that feature determines the reliability of your assembly and the efficiency of your production line.

 

One of the most common mistakes in a machine shop is confusing Nominal Depth (the total depth of the drilled hole) with Functional Thread Engagement.


  • The Risk: If you only measure to the bottom of the hole, you may not have enough full thread ridges to support the fastener's load.
  • The Leitech Solution: A COMBI Gage is calibrated to the First Full Thread Ridge. This ensures that when the gage says 15mm, you have $15mm of fastener-ready thread.

Many machinists still rely on "counting turns" of a standard plug gage to estimate depth. In a modern Quality Control environment, this is a liability:


  • Subjectivity: One operator’s "tight" turn is another’s "loose" turn.
  • Transcription Errors: Manually counting and writing down turns leads to data gaps in PPAP (Production Part Approval Process) documentation.
  • Inefficiency: It’s slow. Speed is the byproduct of using the right tool for the job.

 

To achieve Metrological Certainty, you need Actual Numerical Values. The Leitech COMBI Gage is the only patented solution that verifies Functional Size (Go/No-Go) and Direct Numerical Depth simultaneously.


  • For the Machinist: You get the exact data needed to adjust CNC tool offsets in real-time.
  • For the Quality Manager: You get 100% traceable data for SPC (Statistical Process Control) and audit compliance.

 

Inspecting threads in a blind hole is notoriously difficult. Standard gages with "depth steps" only give you a rough estimate.


  • Pro Tip: Use a gage with a Telescoping Measuring Sleeve. This ensures the gage is perfectly square to the part face, delivering a repeatable measurement regardless of operator "feel." For dark or recessed areas, the Hi-Resolution locking device "freezes" the reading so you can verify it under proper lighting.

 

The same principles of integrated depth control apply to non-threaded features. If you are verifying an ISO H7 fit in a reamed bore, using a Cylindrical COMBI Gage allows you to verify diameter and seat depth in a single motion, ensuring your press-fit components are perfectly seated.

 

Modern manufacturing is moving toward Sustainable Metrology. Instead of treating gages as disposables, the Leitech system uses Member Removal Sleeves and Calibration Masters. This allows you to renew your handles indefinitely by simply replacing the worn thread member—reducing waste and lowering your total cost of ownership.

What is the best way to measure Thread Depth and functional size simultaneously?

Leitech COMBI Gages measure functional Size and direct numerical Depth data - at the same time.  Dual measurements, one tool. 


By replacing subjective "eyeballed" estimates, unreliable turn-counting and depth-steps with a telescoping sleeve to provide actual, traceable, numerical data for tapped, bored, and reamed holes, Leitech empowers Quality Managers and Engineers to ensure absolute part integrity and process compliance in a single operation.


Whether managed by Metrology Gage Lab Departments or utilized by CNC Machinists on the shop floor, Leitech COMBI Gages provide the Industry 4.0 data-driven certainty required by Manufacturing, Design, Process,  Production and Tooling Engineers for modern, high-precision manufacturing.


    Simultaneous Size and Depth Measurement: Threaded or Cylindrical Holes

    As the GO thread member enters the feature, the internal telescoping measuring sleeve automatically rests against the part face, providing a direct numerical depth reading. This single-operation approach eliminates the need for separate depth micrometers or the unreliable practice of counting turns or eyeballing depth steps.

    Applications Across Industries

    • Threaded blind holes: Tapped holes, bottoming threads, threaded features
    • Cylindrical features: Reamed holes, bored holes, drilled bores
    • Industries: Aerospace, Automotive, Medical Devices, Heavy Equipment, Oil & Gas, Defense

      The Variable-Depth Advantage:


    • One Tool, Infinite Depths: A single Leitech gage replaces an entire set of fixed-depth step gages. Whether you have one part with multiple depths or several parts with the same thread size, one tool measures them all directly.
    • Eliminate Guesswork: Replace subjective "eyeballing" with NIST traceable numerical values for GR&R studies. This actual data also allows for immediate, precise adjustments to CNC offsets and tapping machines.
    • Metrological Sustainability: Reduced waste starts with a smaller tool inventory. Fewer gages mean lower calibration costs, less storage, and zero redundant tooling waste.


    if it's a hole in a precision part, we can measure it

    Metrological Certainty: One Tool. Two Critical Measurements.

    Whether inspecting threaded features or cylindrical bores, the Leitech COMBI ensures a perfect assembly fit every time. By verifying functional size and actual depth simultaneously in one fluid motion, you eliminate the need for separate depth micrometers and the unreliable "counting of turns." 

    Inventory Efficiency: The Power of the Universal Gage.

    Experience a leaner Gage Lab. Because one Leitech COMBI measures variable depths for its specific size, a single tool can replace an entire set of traditional fixed-step gages. This drastically reduces calibration overhead and ensures you always have the right tool for any part depth on the print. 

    Digital Integration: The Future of Traceable Data.

    Elevate your process with the Digi-COMBI and DMG-Motorized series. These Industry 4.0 solutions offer high-resolution LCD displays and wireless data transfer, allowing you to capture actual numerical values for real-time SPC logging and 100% digital traceability. 

     

     

    The Challenge: Subjective Thread Inspection

    Traditional thread inspection requires separate tools and multiple operations, leading to critical inefficiencies.


    • Zero Traceability: "Counting turns" is subjective and error-prone.
    • Limited Data: Standard "depth steps" only indicate pass/fail—not the actual numerical measurement values required for modern quality audits.
    • Accessibility Issues: Blind holes and bottoming threads remain difficult to access and verify with traditional methods.


     


     

    The Leitech Solution: One-Operation Efficiency


    Our precision telescoping sleeve provides an instant, error-proof depth reading while the GO member verifies functional size in one fluid motion. Whether inspecting aerospace blind holes, automotive tapped holes, or medical features, Leitech delivers metrological certainty where estimation fails.


    • 50% Faster Inspection: Eliminate guesswork and turn-counting to reduce your inspection time by half.
    • Direct Numerical Data: Deliver 100% traceable, numerical readings for NIST-compliant quality audits and SPC integration.
    • Standardized Consistency: Eliminate operator variability with standardized torque (DMG) to ensure maximum GR&R.

     

    The Result: Inventory Efficiency & Tool Longevity


    Stop buying multiple gages to check a single thread size. One patented Leitech COMBI Gage replaces an entire set of fixed-depth tools, allowing you to measure variable thread depths across various precision parts with one instrument.


    • Sustainable Metrology: Utilize Member Removal Sleeves to extract worn inserts, keeping the precision handle in service indefinitely.
    • Infinite Renewal: Use a Calibration Master (Standard/Hi-Res) or Setting Discs (Digi/DMG) to reset the depth scale and renew your handles for a lifetime of use.

    Standardized Thread Depth Gaging Solutions for Manufacturing

    Faq's: Thread Depth Inspection

    General & Performance

    Q: What is the most efficient way to measure functional thread depth?

    A: The Leitech COMBI Gage performs a functional size check and delivers a direct numerical depth reading in a single operation, eliminating the need for separate depth micrometers or unreliable turn-counting methods.


    Q: How do you inspect and verify the depth of a tapped blind hole or bottoming thread?

    A: The Leitech COMBI utilizes a precision telescoping sleeve that automatically rests against the part face as the GO member enters the thread. This provides a repeatable, traceable measurement of functional thread engagement depth for the fastener, preventing assembly failure and bottoming-out.


    Q: What is "functional thread depth" and why does it matter?

    A: Functional thread depth is the actual usable thread available for fastener engagement, measured from the first full thread ridge. Unlike nominal depth (which only measures to the bottom of the hole), functional depth ensures assembly safety and prevents fastener bottoming-out failures.


    Q: Can I use Leitech gages for cylindrical holes? 

    A: Yes. System Leitech provides the same "Size + Depth" efficiency for cylindrical features as it does for threads. Our Cylindrical COMBI Gages verify the functional diameter of reamed, bored, or drilled holes while simultaneously capturing a direct numerical depth reading.


    Q: How does Leitech reduce gage inventory costs? 

    A: Unlike fixed-step gages that only check one depth, the COMBI's telescoping sleeve measures variable depths directly. One tool replaces an entire set of fixed gages for that thread size.


    Q: How much faster is Leitech compared to traditional methods?

    A: By combining size and depth verification into one operation, Leitech reduces inspection time by approximately 50% compared to using separate gages or counting turns.


    Technical & Compliance

     Q: Is the Leitech COMBI system compliant with FED-STD-H28?

    A: Yes. The Leitech system provides full conformance to FED-STD-H28, Section 6A. The crest of the first full thread on Leitech GO members is held to a strict 0.5 pitch tolerance (+0 / -0.06 pitch) from the front face.


    Q: What is the difference between "functional depth" and "nominal depth"?

    A: Functional depth measures the actual usable thread available for a fastener to engage, accounting for the thread lead-in. Nominal depth simply measures to the bottom of the hole. Leitech gages are calibrated to provide functional depth—the measurement that matters for assembly integrity.


    Q: How do I eliminate "operator feel" variability in thread gaging?

    A: The Digital Motorized Gauge (DMG-COMBI) uses a motorized handle to apply standardized, consistent torque for every measurement, completely removing operator variability from the inspection process.

    Maintenance & Automation

     Q: How do I calibrate a Leitech COMBI Gage?

    A: Calibration is performed using the Leitech Calibration Master to establish a precise, pitch-based Calibration Length (X). By adjusting the telescoping measuring sleeve to this traceable constant, Quality Manufacturing Managers ensure 100% measurement accuracy. This repeatable process guarantees that your thread depth data remains compliant with ISO/IATF and FED-STD-H28 international standards.


    Q: Can I integrate Leitech gages into an automated SPC system?

    A: Yes. The Digi-COMBI and motorized DMG-COMBI are engineered for Industry 4.0 integration, featuring RS232 and wireless data output for real-time SPC (Statistical Process Control). By transmitting actual numerical depth values directly to your quality software, these gages eliminate manual data entry errors and provide the 100% traceability required in modern, high-precision manufacturing.


    Q: Can one Leitech gage measure different thread depths of the same size?

    A: Absolutely. This is the core of Leitech Inventory Efficiency. Unlike traditional fixed-step gages that only verify one pre-set dimension, a single Standard COMBI Gage utilizes a telescoping sleeve to provide a direct numerical reading of any depth within its range. This allows Gage Labs to replace an entire set of several gages with one universal tool, significantly reducing calibration costs. 


    Q: Can Leitech gages be used in automated robotic inspection cells?

    A: Yes, the DMG-COMBI (Digital Motorized Gage) is specifically designed for robotic automation. It features variable speed settings and wireless data transmission, but its greatest advantage is standardized motorized torque. By eliminating "operator feel" and providing consistent measurement force, the DMG-COMBI ensures maximum GR&R (Gage Repeatability and Reproducibility) in 24/7 automated production environments.

    Technical Glossary: Thread Depth Measurement Terms

    Blind Hole / Bottoming Thread

    Cylindrical Size & Depth Control

    Blind Hole / Bottoming Thread

     A threaded or cylindrical hole that does not break through the part. Accurate depth measurement is critical here to prevent fasteners from bottoming out before achieving full engagement. 

    Functional Thread Depth

    Cylindrical Size & Depth Control

    Blind Hole / Bottoming Thread

      The actual usable length of thread that can accept a fastener, measured from the first full thread ridge. Unlike nominal depth, this ensures sufficient engagement to meet load requirements. 

    Cylindrical Size & Depth Control

    Cylindrical Size & Depth Control

    Cylindrical Size & Depth Control

     Dual-purpose measurement for non-threaded features like reamed bores or precision-drilled holes. System Leitech provides the same one-operation efficiency for these features as it does for threads.ads.

    Crest of the First Full Thread

    Operator Variability / "Operator Feel"

    Cylindrical Size & Depth Control

      The specific reference point for Leitech depth measurement. A telescoping sleeve rests on the part face to provide a direct reading of this dimension while the GO member simultaneously verifies pitch diameter size.
     

    Calibration Length (X)

    Operator Variability / "Operator Feel"

    Operator Variability / "Operator Feel"

     The precise distance from the front face of the thread member to the zero-point on the measuring sleeve. This value ensures the gage conforms to FED-STD-H28 and international standards. 

    Operator Variability / "Operator Feel"

    Operator Variability / "Operator Feel"

    Operator Variability / "Operator Feel"

     Inconsistency in results caused by different individuals applying varying force. The DMG-COMBI eliminates this variable through motorized, standardized measurement force. 

    Actual Traceable Numerical Value

    Actual Traceable Numerical Value

    Actual Traceable Numerical Value

     Unlike "Go/No-Go" gages that provide only a binary pass/fail result, Leitech delivers a direct numerical reading. This data allows for precise CNC tool-offset adjustments based on quality audit-ready data. 

    Member Removal Sleeves

    Actual Traceable Numerical Value

    Actual Traceable Numerical Value

     Specialized extraction tools used to quickly and safely remove worn inserts from the Leitech handle. This allows you to renew the tool indefinitely, minimizing physical waste.

    Functional Thread Size

    Actual Traceable Numerical Value

    Gage Inventory Efficiency

      The verification that a threaded feature will accept its mating part. A Leitech "GO" member verifies size while the integrated sleeve simultaneously measures depth in one fluid motion.

    Gage Inventory Efficiency

    Tool Longevity (Sustainable Metrology)

    Gage Inventory Efficiency

    A core benefit where a single variable-depth COMBI gage replaces a set of numerous traditional fixed-step gages. This significantly reduces Gage Lab overhead and calibration costs. 

    Metrological Certainty

    Tool Longevity (Sustainable Metrology)

    Tool Longevity (Sustainable Metrology)

      The elimination of operator subjectivity—such as "counting turns"—in thread inspection. Leitech provides a repeatable, data-driven process that ensures every feature meets exact engineer specifications.

    Tool Longevity (Sustainable Metrology)

    Tool Longevity (Sustainable Metrology)

    Tool Longevity (Sustainable Metrology)

    Leitech gages are engineered for a lifetime of service via a patented design where worn inserts are easily replaced while the precision handle remains.  

     

    Stop guess and start measuring! From the standard workhorse to motorized automation, there is a Leitech COMBI solution designed to bring 100% metrological certainty to your shop floor. 


    Contact us today for a quote or a live demo of the COMBI system.  


    Authorized Master Distributor and Technical Support for the USA, Canada, Mexico and Puerto Rico.

    Contact Us

    Leitech US

    1134 N. 9th St.

    Milwaukee, WI 53233

    414 - 333 - 6310

    Request a Quote

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