How Should You Approach Measuring Internal Grooves?

measuring internal grooves

Do you know that manufacturing a groove on a turned up part is actually easier than inspecting it? With this fact in mind, it is important to select the right measuring tools for internal grooves. Good gaging practice should always be maintained since grooves play a critical function especially for retainer rings and seal rings. There are different types of gages in the market that can measure grooves internally and externally. In this post, we will focus more on gages used to examine grooves internally. Let’s look at different types of gages used to measure internal grooves, their designs, and how they function.

Pistol-Grip Groove Gages

The pistol-grip groove gage is specifically designed to measure internal grooves. This type of gage has a long retraction that measures ½”/13mm to allow it to fit inside a bore and then expand to the full depth of a groove. The pistol-grip gage has an indicator that is smaller than the retraction which can either be digital or dial and has a resolution of 0.0005″/0.01mm. A reference contact is fixed at the bottom of the gage to support the weight of the instrument while a more sensitive contact is located above.

About the Pistol-Grip Gage’s Design

The contacts on a pistol-grip gage are designed to resist flexing when the gage is rocked. They can be adjusted over a range of 25mm to 50mm which makes it easy to inspect different groove parts with a single gage. A single groove gage is capable of using interchangeable contact tips. There are special contact shapes designed to make it easy to inspect V-bottom and round grooves, and extra-long contacts that are capable of accessing deeply spaced grooves.

Caliper Gages

Another type of groove measuring instrument is the caliper gage. Caliper gages are widely used to measure inside grooves since they can be applied to a wide range of inside dimensions. Unlike pistol-grip gages, caliper gages are over ¾”/75mm and have the capability of measuring through their entire retraction range. They are recommended to measure features where large variations are expected and also where different size parts need to be measured without making adjustments. As much as they are easy to use and don’t require any adjustments, their flexibility and range is poorer than pistol-grip gages.

About the Caliper Gage’s Design

Caliper gages have dial indicators that are long ranged with revolution counters or secondary dials. The digital caliper gage is more accurate. However, compared to pistol-grip gages, caliper gages are not engineered to promote rocking. Caliper gages are more popular than pistol-grip gages because they easy to use, less expensive, smaller, and lighter. They also offer a variety of contact styles that make it easier to access difficult features.

For years, manufacturing companies have been using groove measuring instruments to determine whether work pieces are within tolerance, within a short time. These precision measurement instruments are used to inspect recesses easily and quickly.

At Willrich Precision Instrument, we carry a wide variety of gages that can measure internal grooves, in different industrial applications. We have a team of experienced technicians that is more than happy to help you get the right measuring instrument for internal groove measurements. For more information, don’t hesitate to contact us today!

by George Chitos

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