Thread Depth Gages

Leitech COMBI Gages are the precision standard for thread depth inspection in automotive, aerospace, medical, energy and industrial manufacturing.

Why Leitech "COMBI" Thread Depth Gages?

Because the Leitech COMBI handle does something no standard handle does: it surrounds the GO member with a calibrated telescoping sleeve that simultaneously measures functional thread size and depth.

COMBI — a combination of size verification and depth measurement. One tool. Two critical measurements.

That's the whole idea. And it changes everything about thread depth inspection.

System Leitech — The Solution for Thread Depth Inspection

THE PROBLEM: Traditional thread depth inspection is a bottleneck. Machinists check size with a standard plug gage, then estimate depth by counting turns, eyeballing depth steps, or reaching for a secondary depth mic. The result: inconsistent data, operator fatigue, and zero traceability for the modern quality lab.

THE SOLUTION: Leitech COMBI Gages. One thread depth gage verifies functional thread size AND delivers a direct numerical depth reading — simultaneously. No estimation. No second tool. No guesswork.

THE Leitech SYSTEM DELIVERS:

Direct Numerical Depth — A telescoping sleeve reads actual depth the moment the GO member enters the hole

NIST-Traceable Accuracy — Every instrument calibrated to ISO 1502 and FED-STD-H28

Industry 4.0 Ready — Digital models output directly to your SPC system via RS232 or wireless

High-Tolerance Engineering — From automotive production floors to aerospace gage labs

Renewable by Design — Replace worn thread members, keep the handle. Your investment lasts indefinitely.

Leitech COMBI Gages — How to Measure Thread Depth

Leitech Standard COMBI — The Production Workhorse

The instrument that started it all. 0.5mm / 0.025" resolution. Spring-loaded telescoping sleeve. Direct numerical depth reading the moment the GO member enters the hole. Replaces entire sets of fixed-depth gages. One tool covers variable depths across multiple parts and multiple thread sizes.

No turn-counting. No depth mics. No estimation. This is the gage that changed how manufacturers think about thread depth inspection.

The best demo is in your hands. Ask us about a free demo gage in your exact thread size — we'll send it to you. No obligation.

REquest a Demo gage

Leitech Hi-Resolution COMBI — Precision in Tight Spaces

Built for aerospace, medical, and defense components where tighter depth tolerances are a compliance requirement, not just a quality preference. 0.1mm / 0.005" resolution with a unique locking device that freezes the depth reading — so you capture the value in a confined space and read it once the tool is removed. Calibrated to FED-STD-H28. NIST-traceable from day one. When "close enough" means a failed audit, this is the instrument.

Leitech Digi-COMBI - Digital Gaging with Wireless SPC

0.01mm / 0.0005" LCD readout. RS232 and wireless output. Direct integration into your SPC system — no manual entry, no transcription errors, no paper logs. Eliminates parallax error and operator subjectivity. Toggles between metric and inch instantly. Built for Industry 4.0 shops that need a complete digital audit trail for every threaded hole. This is thread depth inspection for the modern quality lab.

Leitech DMG — Power-Driven Thread Depth Gaging

Standardized motorized torque. Every check. Every shift. Every operator. No variability. Built for high-volume production lines where manual gaging creates fatigue, inconsistency, and GR&R problems. The DMG (Digital Motorized Gage) combines the speed of powerdriven thread gaging with the precision of a depth calibrated Leitech instrument. Size and depth. Simultaneously. At production speed.

Leitech - The Variable Depth Advantage

Five fixed-depth thread gages for five different depths of the same thread size — illustrating tradi

The Old Method - One Gage Per Depth

This image shows five gages for five depths of the same thread size. But it could be two. It could be twenty-seven.

Traditional fixed-depth gaging means a separate gage for every depth requirement — more parts, more calibrations, more cost.

One Leitech COMBI gage measuring variable thread depths of the same thread size — directly, numerica

The Leitech Method - One Gage. Any Depth.

One Leitech COMBI checks every depth of that thread size — directly, numerically, traceably.

Same thread size. Variable depths.

One tool. Done.

Leitech COMBI gage inventory — a leaner, smarter alternative to traditional fixed-depth thread gage

The Result - A Leaner Gage Lab

A leaner gage inventory. Lower calibration overhead. Zero redundant tooling waste.

This is what Gage Inventory Efficiency looks like in a modern gage lab.

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

Standard COMBI: The Production Workhorse

DMG COMBI: The Ultimate in Consistency

Standard COMBI: The Production Workhorse

The Problem: Traditional gaging requires multiple tools or unreliable turn-counting to estimate depth. Fixed-depth gages multiply costs and clutter the gage lab.

The Leitech Solution: One Standard COMBI measures any depth within its range, delivering the actual numerical value needed to adjust CNC offsets — instantly.

Impact: Repla

The Problem: Traditional gaging requires multiple tools or unreliable turn-counting to estimate depth. Fixed-depth gages multiply costs and clutter the gage lab.

The Leitech Solution: One Standard COMBI measures any depth within its range, delivering the actual numerical value needed to adjust CNC offsets — instantly.

Impact: Replaces entire sets of fixed-depth gages. One tool covers variable depths across multiple parts. 0.5mm / 0.025" resolution. Built for high-volume production floors.

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

Hi-Res COMBI: Precision in Tight Spaces

DMG COMBI: The Ultimate in Consistency

Standard COMBI: The Production Workhorse

The Problem: Tighter tolerances and confined spaces force operators to guess depth readings or remove the part entirely for measurement.

The Leitech Solution: 0.1mm / 0.005" resolution with a unique locking device that freezes the depth reading — so you capture the value in a hard-to-reach area and read it once the tool is removed.
Impa

The Problem: Tighter tolerances and confined spaces force operators to guess depth readings or remove the part entirely for measurement.

The Leitech Solution: 0.1mm / 0.005" resolution with a unique locking device that freezes the depth reading — so you capture the value in a hard-to-reach area and read it once the tool is removed.
Impact: The go-to instrument for aerospace, medical, energy, and defense components where depth variance is a compliance issue, not just a quality issue.

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

Digi-COMBI: LCD Display and Wireless Data

DMG COMBI: The Ultimate in Consistency

The Problem: Manual data entry slows the shop floor and introduces transcription errors in the gage lab. Paper logs don't satisfy modern quality audits.

The Leitech Solution: Ultra-precise 0.01mm / 0.0005" LCD readout with RS232 and wireless output for instant, error-free data collection directly into your SPC system.

Impact: Elimin

The Problem: Manual data entry slows the shop floor and introduces transcription errors in the gage lab. Paper logs don't satisfy modern quality audits.

The Leitech Solution: Ultra-precise 0.01mm / 0.0005" LCD readout with RS232 and wireless output for instant, error-free data collection directly into your SPC system.

Impact: Eliminates parallax error, manual entry, and operator subjectivity. Built for Industry 4.0 shops that need a complete digital audit trail for every threaded hole.

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

DMG COMBI: The Ultimate in Consistency

The Problem: Operator feel and torque variability produce inconsistent readings across shifts and automated cells. Human fatigue compounds the problem in high-volume environments.
The Leitech Solution: Standardized motorized torque ensures identical entry force for every single measurement — shift after shift, operator after operator

The Problem: Operator feel and torque variability produce inconsistent readings across shifts and automated cells. Human fatigue compounds the problem in high-volume environments.
The Leitech Solution: Standardized motorized torque ensures identical entry force for every single measurement — shift after shift, operator after operator.
Impact: Engineered for maximum throughput in automated environments. Combines the speed of power-driven gaging with the precision of a calibrated Leitech instrument.

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The Guide to Thread Depth Inspection

In precision manufacturing, a thread that is "close enough" is a failure. Here are the questions every Quality Engineer, Machinist, and Metrologist needs answered — and the answers that make the difference.

Q1: What is the most efficient way to measure thread depth and functional size simultaneously?

The Leitech COMBI Gage performs both measurements with one tool. As the GO member verifies functional thread size, the telescoping sleeve rests against the part face and delivers a direct numerical depth reading — simultaneously. No turn-counting. No secondary tools. No estimation.

Q2: What is functional thread depth and why does it matter?

Functional thread depth is the actual usable thread available for fastener engagement, measured from the first full thread ridge. It is not the same as the physical depth of the drilled hole. Insufficient functional depth causes fasteners to bottom out before achieving full engagement — a critical failure point in aerospace, automotive, and medical assemblies. The Leitech COMBI Gage measures functional thread depth directly — from the first full thread ridge — in the same operation as size verification.

Q3: How do I inspect a blind hole or bottoming thread accurately?

Blind holes are where traditional methods fail most. Counting turns is an estimate, not a direct measurement. Depth mics require removing the part. The Leitech COMBI telescoping sleeve automatically contacts the part face as the GO member enters the thread — giving you a repeatable, NIST-traceable depth reading without removing the part or switching tools.

Q4: What does NIST-traceable thread depth measurement mean?

NIST-traceable means your measurement can be traced back through an unbroken chain of calibrations to national standards. Every Leitech instrument is calibrated per ANSI/ASME B1 and FED-STD-H28 from the first full thread ridge — making your depth data audit-ready for compliance.

Q5: How do I reduce gage inventory and calibration costs?

Fixed-depth step gages require one tool per depth requirement — which means dozens of gages, dozens of calibration cycles, and a cluttered gage lab. One Leitech COMBI measures any depth within its range for that thread size. Leading manufacturers across automotive, aerospace, and industrial production have reduced gage inventory by up to 72% after standardizing on Leitech.

Q6: Can Leitech gages measure cylindrical holes — not just threads?

Yes. The Leitech Cylindrical COMBI provides the same simultaneous size-and-depth measurement for reamed bores, drilled holes, and precision cylindrical features. Same one-operation principle — functional diameter verified, actual depth read, in a single operation. Commonly specified for hydraulic manifolds, pneumatic components, fuel systems, and precision machined housings where both bore size and depth are critical.

Q7: How long does a Leitech COMBI Gage last?

Indefinitely. When the GO thread member wears, you replace the member — not the handle. The depth-reading handle stays in service permanently. Using the Leitech Calibration Master or Setting Discs, the scale is reset and the gage is renewed in minutes. This renewable design reduces long-term tool costs by up to 60% compared to replacing entire gages. The handle you buy today is the handle you'll use in twenty years. Only the gage inserts ever change.

Thousands of Cusotmers. One Standard. System Leitech.

Leitech-US has supplied precision manufacturers across North America — including these industry leaders and the thousands of Tier 1 suppliers and precision machine shops across the US, Canada, and Mexico that make the parts that make the world work.

Including: Caterpillar, John Deere, Ford, General Motors, Tesla, SpaceX, Toyota, Honda, Hyundai, Nissan, BMW, Aisin, Denso, Magna, ZF, Linamar, Nemak, GKN, Borg Warner, Dana Corporation, Bendix, Getrag, CNH, Navistar, PACCAR, Cummins, Briggs & Stratton, Kohler Engines, Kawasaki, Ryobi, Harley-Davidson, Mercury Marine, Hydro-Gear, Crown Equipment, Collins Aerospace, Lockheed Martin, Northrop Grumman, Raytheon, L3 Harris, BAE Systems, Bell Flight, Pratt & Whitney, GE Aerospace, Rolls-Royce, General Dynamics, Leonardo DRS, Lisi Aerospace, Hartzell Propeller, Sikorsky, Safran, SKF, Hitachi Astemo, Parker Hannifin, Eaton, Danfoss, Honeywell, Emerson Electric, TEAM Industries, Robert Bosch, Danaher, ITT, Moog, Jabil, Pace Industries, Zimmer Biomet, Stryker, DePuy Synthes, Medtronic, Arthrex, Microport Orthopedics, Autocam Medical, Orchid Orthopedics, Viant Medical — and many more.

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Thread Size and Depth. Measured Simultaneously.

Leitech : This is How Thread Depth Inspection is Done

One "Combi" Gage. Two Measurements. Checks size AND depth - at the same time!

Leitech US

1134 N. 9th St.

Suite 280

Milwaukee, WI 53233

Phone: 414-333-6310

leitech.com

Leitech Gages. Any Depth. Threaded or Cylindrical.

Standard. Hi-Resolution. Digital. Powerdriven.

System Leitech — The Solution for Thread Depth Inspection

Leitech COMBI Gages — How to Measure Thread Depth

Leitech Standard COMBI — The Production Workhorse

Leitech Hi-Resolution COMBI — Precision in Tight Spaces

Leitech Digi-COMBI - Digital Gaging with Wireless SPC

Leitech DMG — Power-Driven Thread Depth Gaging