How to Use an Electronic Cylinder Bore Gauge
- 1). Assemble the gauge so it resembles an upside-down "T." Attach the stem (the long part of the tool that you hold with your fingers) to the measuring head and insert a properly sized post into the caliper. The measuring head is the part of the tool that will span the cylinder bore to determine it's exact dimensions. The post is just a metal spacer which makes the measuring head longer or shorter so that is will fit snugly inside the cylinder bore. The post you select to insert into the caliper will depend upon the size of the bore to be measured. The measuring head must fit snugly inside the bore to make an accurate measurement.
- 2). Select a post that is best suited for the measurement of the "master" ring, which is a standardized diameter calibration piece that comes with nearly all gauges. On some model gauges, a different post is not needed for calibration, so this requirement varies by model. To accurately measure a cylinder bore, you must take two measurements. The first measurement is used to calibrate the tool; the second measurement is the actual cylinder bore measurement.
- 3). Enter the actual known diameter of the master ring into the tool, following the specific instructions provided with the caliper. Fit the caliper to the master ring, then "zero" the gauge at this exact diameter. This is normally done by pressing the "zero" or "cal" button on the face of the tool. When successfully completed, if you re-measure the calibration ring (for example, pretend it is the cylinder bore), the tool will display the ring's measured size--which will be exactly the same as the ring's actual known size.
- 4). Fit the correct size post identified in step one into the tool. Note the post size that you are using. The difference between the calibration post size (if any was used) and the measurement post you will be using will be manually added to the final reading value. This will compensate for the extra space you are adding to the tool by using a larger post. The size of the measurement post can be added during the calibration phase in some models, but doing so adds complexity to the calibration step.
- 5). Wipe off the tool to remove any debris from the posts. Turn it on by pressing the "on" switch usually located on the base of the unit. The bore gauge assembly is now ready to measure the cylinder. Introduce the bore gauge to the cylinder on a slight angle. Rock the gauge back and forth, which will compress the spring-loaded caliper post.
- 6). Note the minimum measurement in the tool's LED display; this is the diameter of the cylinder at the measurement point. For typical cylinder honing and boring operations, this measurement will need to be repeated several times throughout the height of the cylinder. Re-check the calibration against the master ring periodically to ensure maximum measurement accuracy.
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