How to Measure Bores in Aluminum Castings

Aluminum castings take on various forms, many of which may include bored features. Transmission housings and alternator brackets are two such examples of castings that have bored features that should be measured, especially to ensure all bore diameters are within a specified tolerance range. Measuring these bores requires using a measurement tool that can reliably reproduce the same results. Whether you are using digital, dial or vernier calipers, the measurement needs to be correct. If you are correct, the measurement will be statistically the same each time you measure the exact same feature.

Things You'll Need

• Caliper

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Instructions

1. • 1

     Place the internal caliper jaws inside the bore. If your caliper has a thumb screw to prevent sliding action to preserve a measurement, loosen it so the caliper jaws can later be adjusted freely.

   • 2

     Adjust the caliper jaws to the bore diameter. The jaws should lightly touch the walls of the bore.

   • 3

     Remove the caliper from the bored feature. Tighten the thumb screw to preserve the measurement. Obtain the reading from the caliper to determine the diameter of the bore per the instructions supplied with your specific type of caliper.