Air Gages

Air gaging is the fastest, most repeatable way to measure inside diameters, outside diameters, and geometric form on the shop floor. Instead of touching the part, an air gage reads a dimension from the back pressure or flow of air escaping between precision jets and the workpiece — so it is non-contact, self-cleaning, and accurate to millionths of an inch, with typical magnification from 1,000:1 to 10,000:1. Because it measures from the mean surface rather than from roughness peaks, air gaging gives a truer reading than contact methods, at production speed. WESTport has manufactured, sourced, and calibrated air gaging systems since 1989 in a climate-controlled, ISO/IEC 17025 accredited facility.

The WESTport air gaging line

This collection covers the complete air gaging system — from a single replacement plug to a fully configured multi-channel setup. Every item is compatible with Mahr/Federal, Edmunds, Sheffield, GAR, Universal Gage, and Western Gage tooling, so you can expand or upgrade without rebuilding your gaging system.

• Air Plugs (internal diameter). Opposed air jets measure bore ID with sub-micron repeatability from 0.120″ to 6.010″. Standard through-hole, blind-hole, counterbore, deep-hole / long-reach, leaf-contact (for cast, knurled, or interrupted surfaces), and taper styles.
• Air Rings (external diameter). Jets set around the ring bore measure shaft and OD dimensions as the part passes through — faster and more repeatable than snaps for high-volume work. Standard fixed-size, adjustable, and split / flanged configurations.
• Air Snap Gages. A C-frame or fork that brings the jets to the part instead of the part to the gage — ideal for long shafts and large components. Fixed, adjustable, and blade-type groove-width models for OD, wall thickness, and groove checks.
• Air Spindles. Plug-style tooling built for long bores and automated, in-process gaging cells. Standard and long / extended-reach lengths.
• Digital Comparators & Amplifiers. Single- and multi-channel (2–8 channel) readouts with USB, RS232, RS485, and Ethernet output for direct SPC integration. Our SR1-TR is a drop-in replacement for Federal D1250–D8000, GAR, TRICO, and OILMASTER columns — swap the readout, keep the tooling.
• Setting Masters. Air gaging is a two-point system: a minimum and maximum master define the zero and span of your readout. We manufacture master ring gages, master setting discs, and master plug gages — precision ground and hand-lapped, with NIST-traceable long-form certification.
• Jet Probes, Nozzles & Accessories. Replacement jet probes and nozzle bodies, plus the air regulators, filters, hose and connector assemblies, and manifolds that keep a system delivering accurate readings.
• Oil Well Gaging. The SR1-TR configured for subsurface pump-barrel inspection, with probes and spindles in sizes 1.000″–5.000″ and hose assemblies to 60″.
• Custom Air Gages. Taper, multi-jet, differential, and automated in-process gages engineered to your print. Send a drawing with nominal dimensions and tolerances to start a quote.

What air gaging inspects

Beyond straight ID and OD, air gaging captures the geometric characteristics that are hard to measure any other way:

• Inside & outside diameters
• Roundness / averaging
• Straightness & bow
• Taper
• Flatness
• Groove width
• Matching / clearance fit
• Squareness / perpendicularity

Air gaging vs. contact gaging

Contact gaging reads from the surface roughness peaks of the part; air gaging reads from the mean surface — the average of peaks and valleys. That difference is why air gaging is preferred wherever surface finish, speed, or repeatability matters.

Industries served

Why WESTport

• ISO/IEC 17025 accredited, NIST-traceable. Tooling and masters are manufactured and certified in our own climate-controlled laboratory.
• Compatible with every major system. WESTport plugs, rings, snaps, and comparators interchange with Mahr/Federal, Edmunds, Sheffield, GAR, Universal Gage, and Western Gage — upgrade a readout or replace a worn component without changing your setup.
• In-house calibration & repair. We recertify and rebuild air tooling and masters with a 5–7 business day turnaround on most items.
• Made in the USA since 1989. Precision-ground and hand-lapped for accuracy, surface finish, and wear life.