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Fowler/Bowers XT Extreme Bore Gage: Spherical Anvils

Over the next few weeks, Higher Precision will be releasing a series of blogs pertaining to the Fowler/Bowers XT Extreme Series Bore Gages. The Fowler/Bowers XT bore gages are in a class of themselves when it comes to accuracy, repeatability, and quality. Fowler and Bowers have the ability to create customized anvils on the XT bore gages to be able to measure all types of special applications such as grooves, threads, taper, and splines just to mention a few.

Spherical anvils are one of the more popular specials that Bowers can manufacturer. The measuring heads with spherical anvils are commonly used on applications when an operator has to measure deep into a bore. One of the reasons that standard heads are not recommended with deep bore applications is that the operator can not physically see the measuring anvils touching the sides of the bore. If a standard measuring head is tilted the slightest bit, either the top or bottom of each anvil will be touching the bore which will result in the gage displaying a diameter that is actually larger than it is.

When taking measurements with spherical anvils, the gage itself can be up to twelve degrees off from being perpendicular in the bore and still get an accurate reading. The spherical anvils compensate for the gage being tilted. The spherical anvils provide more repeatable results when measuring deep bores. Deep bore applications are the most common when spherical anvils are used but are also popular when an operator is trying to measure the taper of a bore.

Bowers usually recommends using spherical anvils to measure taper instead of having a specific size ball mounted onto the end of standard anvils. The main reason why this is recommend is because the ball contacts are fragile and can easily be broken off if an operator is not careful with the measuring head. If a customer does want ball contacts for a taper application, we are still happy to provide a quote. Typical delivery on a special spherical head is usually about 6-8 weeks depending on how busy Bowers currently is with special orders. Special spherical anvils are available on both 2-point and 3-point heads above .250”/6mm. Any sizes less than this are only available in 2-point contacts.

Stay tuned for more information on other special applications that are available through the Fred V. Fowler Company and Bowers Metrology.

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