Leitech Combi Gages : Depth Calibration
When a Leitech thread gage member wears, it’s important to swap it out and perform a DEPTH CALIBRATION for accurate precision measurement.
The Leitech COMBI Calibration Master
The fastest, most foolproof way to calibrate your Standard or Hi-Resolution Leitech COMBI Gage is through precise depth calibration. Dial in your thread pitch, and the correct calibration length sets automatically. No calipers, no gage blocks, and no guesswork are needed for accurate precision measurement.
Custom Leitech Gage Solutions — Your Problem Is Our Business
Standard gages solve standard problems. But precision manufacturing rarely stays standard.
Angled holes, counterbores, minimal clearances, and arc-formed bottoms can create challenges in precision measurement. Features that are hard to reach, such as deep blind holes in tight spaces, require specialized solutions. If your application includes a thread or cylindrical feature needing size and depth verification that a standard gage can't accommodate, Leitech has the answer with the Leitech COMBI Gage for depth calibration.
Send us a sketch, a drawing, or a 3D model, and describe your challenge. Within days, we’ll develop the solution.
Wear Shoe for Angled Measurements
The Leitech COMBI Gage Wear Shoe enables precise depth calibration on angled or radial surfaces, ensuring accurate depth measurement as the sleeve references the correct datum, regardless of the surface geometry.
The Leitech Ball Measure System
Designed specifically for arc-formed or radiused bottom holes where a flat reference surface doesn't exist, the Leitech COMBI Gage offers an effective solution for depth calibration. The ball contacts the arc, ensuring a consistent and repeatable depth reference for precision measurement.
Special Wear Bushings
Designed for areas with minimal clearances, the Leitech COMBI Gage offers various bushing profiles to facilitate depth calibration and access confined features that standard sleeves cannot reach, ensuring precision measurement in tight spaces.
Measure Angled Holes
Oversize Wear Bushings
For applications requiring a larger reference surface or additional wear protection in high-cycle environments, the Leitech COMBI Gage is ideal for depth calibration and precision measurement.
Special Wear Bushings
Designed for areas with minimal clearances, the Leitech COMBI Gage offers various bushing profiles to facilitate depth calibration and access confined features that standard sleeves cannot reach, ensuring precision measurement in tight spaces.
CUSTOM CAPABILITIES
Cylindrical COMBI Gages utilize the same simultaneous size-and-depth principle applied to reamed bores, drilled holes, and precision cylindrical features. These gages are ideal for depth calibration of core holes, plain bores, and counterbores — all verified for size and depth in one check.
Special Coatings such as Chrome, TiAlN, and DLC are designed for extended wear life in abrasive materials. TiAlN offers up to 10x wear life in aluminum and cast iron, making it the most common upgrade for automotive production environments.
Left-Hand Threads are available upon request for any standard or custom size, ensuring versatility in precision measurement applications.
NPT and Pipe Threads come in standard and custom configurations for pipe thread depth and engagement verification, meeting various industrial needs.
STI / Helicoil Threads are purpose-built for thread insert inspection, effectively verifying the size and depth of STI threaded holes in one operation, enhancing efficiency and accuracy.
Contact us with your drawing, sketch, or description — we'll get back to you with a solution.
The Leitech Customized Concept: we cover the development costs. You pay only for the final solution. Share your problem with us, and we'll create the perfect solution, whether it's for depth calibration or a Leitech COMBI Gage. From a single tool to thousands, we have the flexibility and capability to deliver a precision measurement solution in a manageable timeframe at an acceptable cost.
Why Turn-Counting Fails — And What to Do Instead
Ask a machinist how they check thread depth, and there's a good chance the answer is "I count turns." It's fast, requires no special tools, and has been the norm for decades. However, this method is inaccurate, untraceable, and fails to measure what truly matters.
Here's why:
Most thread depth specifications are measured from the part face, which typically includes the chamfer depth as part of the total functional engagement length. When you count turns, you're starting from when the gage first contacts the thread, which may not align with the part face. This inconsistent reference point is operator-dependent and unverifiable.
The Leitech COMBI Gage addresses this issue by resting directly on the part face—whether flat or angled—providing you with a direct reading from precisely the reference point specified in the print.
For applications requiring depth calibration from inside a counterbore or chamfer—at the exact location where full thread engagement begins—Leitech can modify the gage to measure from that precise datum. You receive the actual length of thread engagement, starting from wherever your design specifies.
If a design necessitates measurement from a specific location, we customize the gage accordingly.
Operator variability is another concern. One inspector counts 10.5 turns; another counts 11. On a 1.5mm pitch thread, that difference translates to 0.75mm—enough to cause a failure in aerospace assembly or result in a fastener bottoming out in a medical device. And when an auditor requests documented, traceable depth data? "I counted the turns" won't satisfy an ISO 1502 or AS9100 audit. There is no data, no traceability, and no record.
The Leitech COMBI Gage solves all three problems at once. The telescoping sleeve contacts the part face—not the chamfer—and delivers a direct numerical reading of functional thread engagement from the first full thread ridge. Every time. Every operator. Fully traceable.
Turn-counting is merely an estimate, whereas Leitech offers precision measurement.
The Numbers Don't Lie: Real Results from the Manufacturing Floor.
45% Faster Inspection
A North American automotive supplier inspecting a complex V12 engine block with 99 threaded holes achieved a significant reduction in inspection time from 71 minutes to 39 minutes after switching to the Leitech COMBI Gage. This single tool not only streamlined the process but also ensured precision measurement and depth calibration, all while maintaining the same operator and parts.
72% Less Gage Inventory
A precision machining facility handling a 16-valve cylinder head with 103 threaded holes replaced an entire drawer of fixed-depth gages with 7 Leitech COMBI Gages. This transition not only reduced the number of tools but also lowered depth calibration costs, resulting in a leaner gage lab focused on precision measurement.
17% Machine Hours Reclaimed
Shops that tap 15-40% deeper than the blueprint requires—just "to be safe"—are wasting spindle time and tap life on every single hole. Implementing depth calibration with tools like the Leitech COMBI Gage allows for precision measurement at the machine, effectively eliminating over-tapping. One U.S. production facility calculated they were threading 374 meters of unnecessary depth per year on a 1,000-holes-per-day operation. That's real money.
These aren't projections.
They're what happens when estimation gets replaced by precision measurement, particularly in processes like depth calibration, as seen with the Leitech COMBI Gage.
Thread Depth Inspection Terms — Know What You're Measuring
Leitech and Quality Control
Leitech and Quality Control
Leitech and Quality Control
Precision manufacturing has its own language, especially when it comes to depth calibration in thread depth inspection. Here are the essential terms you need to know, clearly defined and easy to understand, no engineering degree required.
Calibration Master or Setting Disc: This component ensures that the gage conforms to FED-STD-H28, providing traceable depth readings critical for precision measurement.
Pitch Diameter: This refers to the theoretical diameter of a thread where the width of the thread ridge equals the width of the groove. It is the primary dimension checked by the GO member to confirm that the thread can accept its mating fastener.
Telescoping Sleeve: This is the precision depth-measuring element of the Leitech COMBI Gage. It is spring-loaded and contacts the part face as the GO member enters the thread, delivering a direct numerical depth reading while simultaneously verifying size.
Have a term you don't see here? Feel free to ask the Gage Guys at 414-333-6310 or email tony@leitech.com.
Measurement Terms
Leitech and Quality Control
Leitech and Quality Control
Functional Thread Depth refers to the measured distance from a specified datum point — typically the part face — to the end of useful thread engagement. This measurement is what your print calls out and is directly assessed by the Leitech COMBI Gage.
Thread Engagement is defined as the length of fully-formed, usable thread available for a fastener to grip. It begins at the first full thread ridge and concludes at the last fully formed thread before runout starts. This crucial aspect is what holds your assembly together.
The First Full Thread Ridge serves as the reference point for all Leitech depth measurements. According to FED-STD-H28 and ISO 1502 standards, thread depth must be measured from the first fully formed thread — not from the chamfer or the part face alone. Leitech GO members are manufactured with a strict 0.5 pitch tolerance from this reference point to ensure precision measurement.
Calibration Length (X) is the exact distance from the front face of the Leitech thread member to the zero-point on the measuring sleeve, established using the Leitech depth calibration process.
Gage Terms
Leitech and Quality Control
Data and Quality Terms
Go / No-Go Gaging is the industry standard method for thread size verification. The GO member must enter the threaded hole freely to full depth — confirming the thread is not undersized. The NoGo member must not enter more than two turns — confirming the thread is not oversized. The Leitech COMBI Gage performs both checks while simultaneously measuring depth calibration, ensuring accurate results.
Taperlock Design refers to the method by which Leitech thread members attach to the handle. A tapered shank seats securely in the handle and can be removed using the Leitech Member Removal Sleeve when replacement is needed.
Member Removal Sleeve is a specialized extraction tool used to safely remove worn Leitech thread members from the handle. Green for GO members, red for NoGo members. This tool allows for the renewal of the gage member while keeping the precision measurement handle in service.
Functional Thread Size Verification ensures that a threaded feature will accept its mating part to the correct pitch diameter. The Leitech GO member verifies functional size while the telescoping sleeve simultaneously measures depth.
Data and Quality Terms
Standards and Thread Types
Data and Quality Terms
Gage R&R (Repeatability and Reproducibility) is a statistical measure that assesses how much variation in your measurement results originates from the gage and the operator compared to the actual part. The Leitech COMBI Gage, with its telescoping sleeve, consistently delivers the same reading every time, significantly enhancing Gage R&R compared to traditional turn-counting or caliper methods, particularly in the context of precision measurement.
NIST-Traceable measurement ensures that results can be traced through an unbroken chain of calibrations to national standards, which is crucial for quality audits in aerospace, defense, and medical device industries. Every Leitech instrument is meticulously calibrated to meet FED-STD-H28 and ISO 1502 standards, ensuring reliable depth calibration.
SPC (Statistical Process Control) is a quality control method that utilizes statistical analysis of measurement data to monitor and control manufacturing processes. The Leitech Digi-COMBI and DMG facilitate this by outputting actual numerical depth values directly to SPC software via RS232 or a wireless connection.
Process Terms
Standards and Thread Types
Standards and Thread Types
A blind hole is a threaded or cylindrical hole that does not break through the part. Accurate depth calibration is critical, as fasteners must not bottom out before achieving full engagement.
A bottoming thread or bottoming tap is a tap ground with minimal chamfer, designed to cut threads as close to the bottom of a blind hole as possible. This is common in applications that require maximum thread engagement within limited depth, making precision measurement essential.
Over-tapping refers to the practice of tapping 15-40% deeper than the blueprint requires as a 'safety margin.' This can waste tap life, increase cycle time, and potentially weaken parts. Such issues can be eliminated by utilizing real-time depth monitoring with a Leitech COMBI Gage.
A counterbore is a cylindrical flat-bottomed hole that enlarges a portion of an existing hole. To accurately measure thread depth from inside a counterbore, a modified Leitech gage is necessary, configured to reference the correct datum — the precise location where full thread engagement begins.
Standards and Thread Types
Standards and Thread Types
Standards and Thread Types
UNC / UNF / UNEF (Unified Inch Threads) are the most common thread standards in North American manufacturing. UNC (coarse), UNF (fine), and UNEF (extra fine) are all available in Classes 2B and 3B. Leitech COMBI Gages provide precision measurement across the full range from #2-56 through 1-5/16, ensuring accurate depth calibration for various applications.
Metric / ISO Threads represent the international standard for metric threads, specified by ISO 6H tolerance. Leitech COMBI Gages cover M2 through M33, encompassing the complete range of metric thread sizes used in European and global manufacturing specifications, facilitating precise depth calibration.
JIS (Japanese Industrial Standard) is the thread standard utilized in Japanese manufacturing and by Japanese-owned facilities and suppliers worldwide. Leitech COMBI Gages are available for JIS thread inspection, catering to automotive, electronics, and industrial applications from Japanese OEMs and their North American suppliers, all while ensuring precision measurement.
NPT (National Pipe Taper) is a US standard for tapered pipe threads used in fluid and gas connections. Leitech COMBI Gages are available for NPT and NPTF inspection, featuring 1-pitch and 4-step lines as standard, enabling effective depth calibration for reliable connections.
STI / Helicoil Thread is a thread form used with helical wire thread inserts, common in aluminum and soft material applications requiring thread reinforcement. Leitech produces COMBI Gages specifically for STI thread inspection, ensuring precision measurement in these specialized applications.
Left-Hand Threads are available upon request for any standard thread size and type. If your application necessitates left-hand thread verification with simultaneous depth measurement, Leitech can custom-build a solution to meet your needs.
The Original. The Standard. The Future.
As the authority in precision measurement and depth calibration for over 30 years, Leitech has been more than just a tool manufacturer—we are the architects of the thread depth gaging category. With the introduction of the Leitech COMBI Gage, we transformed inspection from a manual 'guesswork' process into a repeatable, NIST-traceable science.
Our History
In the early days of precision manufacturing, thread depth inspection was akin to a guessing game. Machinists counted turns while inspectors eyeballed depth steps, and quality labs accepted estimation as standard practice.
Then, Leif Larsen of Leitech Instruments in Gilleleje, Denmark, had a simple yet transformative idea: what if one gage could verify thread size and measure functional depth — simultaneously, in a single check, with a direct numerical reading? This innovation led to the creation of the Leitech COMBI Gage, revolutionizing thread depth inspection forever.
Since 1989, Leitech-US has been introducing that Danish innovation to North American manufacturers. Tony Thorson and Mike Thorson have dedicated decades to educating engineers, machinists, quality managers, and metrologists about a superior method of depth calibration — one demo gage at a time.
Over 5,000 companies across the US, Canada, Mexico, and Puerto Rico have standardized on Leitech thread depth gages. From small precision machine shops to the largest automotive and aerospace manufacturers in North America, the reaction is almost always the same:
"Why didn't I know about this sooner?" This approach not only enhances precision measurement but also streamlines the entire inspection process.
Where We're Going
Manufacturing is experiencing a renaissance. Industry 4.0, smart factories, wireless data, automated inspection, and AI-driven quality systems are transforming the shop floor of tomorrow, making it look nothing like the shop floor of yesterday.
Leitech is at the forefront of this transformation.
The Leitech COMBI Gage's wireless SPC output integrates seamlessly into modern quality management systems. The DMG's standardized motorized torque fits perfectly within automated inspection cells. Moreover, the core principle of the COMBI—offering simultaneous size and depth calibration in one check—is more valuable in today’s data-driven manufacturing environment than ever before. Every thread, every hole, every measurement is now traceable, digital, and certain.
This is not just the direction Leitech is heading; it’s where precision measurement in manufacturing is evolving.
We’re already leading the way.