George Schuetz Director of Precision Gages
Understanding Plate Gages
You’ve seen the bench-mounted ID/OD comparative gage with the tilting stage plate to set and locate the part being gaged. This basic design, which has been around for more than 50 years, is convenient for fast, comparative gaging of flat and relatively thin-walled parts, such as ball and roller bearing rings, where diameter measurements must be made in a plane parallel to at least one of the faces, and sometimes at a particular depth on the ID or OD.
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A Novel Use For Air Gaging
Throughout the years, we have discussed many successful uses of air gages in this column. We have seen them used to measure diameters, tapers, straightness and even little bitty holes.
Read MoreImproving Height Gage Results
As with any measurement, the quality of the result depends on the measurement instrument and the care with which the operator handles the measurement procedure. Many gages are designed to make this as easy as possible.
Read MoreSearching For The Perfect Identical Waves
When two different dimensional measuring systems are used on the same part, one would expect to get pretty much the same results. But in certain cases, this may not be true.
Read MoreCalibrating Gages: With Master (And Engagement) Rings, Size Matters
A master ring, or ring gage, is basically a bore of known dimension. The precision hole is often used as a setting master for variable ID gages (such as bore gages, air tooling and mechanical plug gages), for go/no-go mastering of fixed ID gages and for go/no-go OD inspection of male cylindrical workpieces.
Read MoreCalibrating Gages: Your Place Or Mine?
Large companies can cost-justify hiring specialists in gage calibration and keeping equipment to perform calibration in-house. But for most shops, the economical approach is to hire a calibration service.
Read MoreA Probing Look At Probes
The capability of a measuring instrument often comes down to how the contact point interacts with the part being measured—that is, the probe or contact. There are some things to keep in mind when using a contact tip or probe arm as part of your measurement.
Read MoreDimensional Collateral: Do Two Sines Equal A Cosine?
It is not just irony to say that comparative gages have their greatest accuracy at zero. Even though such a gage could provide a direct reading measurement, it is always best to use it as a comparator.
Read MoreGage Block Verification
A QC manager asked if he could verify gage blocks in-house. “You always say the gage maker’s rule of thumb states that any gage used to verify another gage must resolve to ten times its accuracy,” he wrote.
Read MoreGetting My Stars Aligned
Gage design requires certain physical characteristics for reliable performance. A rigid and sound design, for instance, helps ensure that operators have as little influence on the measurement as possible.
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An Inside Look At Special Diameters
Sometimes we are faced with making critical inside diameter checks on parts that do not present themselves in a straightforward fashion. Usually these checks are on the inside of some type of bearing, and they can be almost any size.
Read MoreMicrometer Accuracy: Drunken Threads And Slip-Sticks
Whether it’s a screw thread or digital micrometer, the instrument’s level of precision depends on two factors: the inherent accuracy of the reference (the screw thread or the digital scale) and process errors. With a screw micrometer, accuracy relies on the lead of the screw built into the micrometer barrel.
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