The Authority in Precision Thread Depth Gaging | Leitech US
Leitech COMBI Gages Measure Thread Size and Depth
One Gage ... Two Measurements ... Zero Guessing

The Authority in Precision Thread Depth Gaging | Leitech US
One Gage ... Two Measurements ... Zero Guessing

Leitech COMBI Gages are the precision standard for thread depth inspection
in automotive, aerospace, medical, and industrial manufacturing.
Milwaukee, WI — serving North America since 1989.
As the GO member verifies functional thread size, the telescoping sleeve delivers a direct numerical depth reading — simultaneously. No counting turns. No secondary tools. No estimation.

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 insertion verifies functional thread size AND delivers a direct numerical depth reading — simultaneously. No estimation. No second tool. No guesswork.
THE SYSTEM DELIVERS:
Built for aerospace, medical, and defense components where depth tolerance is 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.
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.
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 combines the speed of power-driven thread gaging with the precision of a calibrated Leitech instrument. Size and depth. Simultaneously. At production speed.

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.





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 checks every depth of that thread size — directly, numerically, traceably. Same thread size. Variable depths. One tool. Done.

A leaner gage inventory. Lower calibration overhead. Zero redundant tooling waste. This is what Inventory Efficiency looks like in a modern gage lab.

In precision manufacturing, a thread that is "close enough" is a failure.
Here are the questions every Quality Engineer, Machinist, and Metrologist needs answered.
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.
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.
Blind holes are where traditional methods fail most. Counting turns is an estimate. 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.
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.
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. Worldwide manufacturers have reduced gage inventory by up to 72% after standardizing on Leitech.
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.
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 Leitech COMBI system measures functional size and actual depth simultaneously — for both threaded and cylindrical features.
Threaded holes: Tapped blind holes, bottoming threads, STI/Helicoil inserts, NPT and pipe threads, metric and unified inch threads in any standard.
Cylindrical holes: Reamed bores, drilled holes, precision cylindrical features — same one-operation principle, same direct numerical depth reading.
** If it's a precision hole in a machined part, Leitech measures it. **
One check. Done.
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Over 35 years serving North American precision manufacturers — including suppliers to 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, 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, Robert Bosch, Danaher, ITT, Moog, Jabil, Pace Industries, Zimmer Biomet, Stryker, DePuy Synthes, Medtronic, Arthrex, Microport Orthopedics, Autocam Medical, Orchid Orthopedics, Viant Medical — and thousands of the Tier 1 suppliers and precision machine shops across the US, Canada, and Mexico that make their parts.

From the Standard COMBI workhorse to the Digital Motorized DMG — there is a Leitech solution for every thread depth inspection challenge on your shop floor, in your gage lab, or on your production line. Authorized Master Distributor and Technical Support for the USA, Canada, Mexico and Puerto Rico. Since 1989.
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