Air Plug Gages (Air Probes)
Air plug gages (also called air plug gauges, air probes or air spindles) measure bore diameter from .059" to 8.260" (1.50 to 209.80 mm) without touching the part. Thru-hole, blind and super-blind styles, as Dual Master or Single Master tooling.
Thru-Hole Air Plug Gage (APT)
Longest-wearing air plug for through bores: the nose guides the plug in and takes the wear.
Sizes: .059" to 8.260" (1.50 to 209.80 mm)
Details & pricing →
Blind-Hole Air Plug Gage (APB)
Jets close to the nose, for measuring near the bottom of a blind bore.
Sizes: .059" to 8.260" (1.50 to 209.80 mm)
Details & pricing →
Super-Blind Air Plug Gage (APS)
Deepest reach into a blind bore, with jets as close to the nose as they can go.
Sizes: .059" to 8.260" (1.50 to 209.80 mm)
Details & pricing →Which style?
| Style | Jets | Best for | Wear life |
|---|---|---|---|
| Thru-hole (APT) | Set back from the nose | Through bores | Longest |
| Blind (APB) | Close to the nose | Measuring near the bottom of a blind bore | Good |
| Super-blind (APS) | As close to the nose as possible | The deepest reach in a blind bore | Shortest |
Small plugs can have a factory extension to reach deep bores, and plugs over 2.510″ come with a heavy-duty handle. Miniature plugs, slot-jet plugs for narrow lands, and multi-diameter plugs are quoted from your print.
Clearance class (Dual Master)
- Class 1, close: highest accuracy, for select-fitting valve spools and sleeves with finish tolerances under .00016″ (4 µm)
- Class 2, standard: right for most jobs, and what we supply unless you specify otherwise
- Class 3, extra: more gaging range for grinding and honing, when you need a reading before the part reaches size
Choosing the right plug
- The reading is taken at the jet, so check where the jets fall relative to grooves, cross holes and chamfers.
- The land being measured must cover the whole jet. A land about twice the jet diameter is a practical minimum.
- A plug can't measure closer to the bottom of a blind bore than the leading edge of its jet.
Dual Master or Single Master?
Dual Master tooling is set with two masters, one at each end of the tolerance, and works with any two-master readout. Single Master tooling is set on one master at nominal and is matched to a single-master readout, such as the Air Gage Pro M5-L or M5-H that replaces Dimensionair readouts. Compare single and dual master.
Questions
Is an air plug the same as an air probe or air spindle?
Yes. They are three names for the same tool: a gaging body with opposed jets that measures bore diameter with air.
What do I need to get a price?
The bore size and tolerance, whether it is through or blind, and whether you want Dual Master or Single Master tooling. Enter them in the online configurator and you'll see the part number and price.
Will your plugs work with my readout?
Dual Master plugs work with any two-master air readout. Single Master plugs must match the readout's amplification; tell us the make and model and we'll match it.
What else do I need?
Masters to set the gage (a ring master, or two for Dual Master), and a handle and hose assembly with the right fitting for your readout.
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