Plug gage calibration procedures are essential for measuring roundness, diameter, and other sizes of cylindrical parts. Proper calibration ensures that plug gages will accurately measure the parts they are intended to measure. The most used method of calibrating plug gages is using a dial indicator or micrometer. 

1) Set Up the Dial Indicator or Micrometer: Securely mount the dial indicator or micrometer in a horizontal position with its spindle centered over the centerline of the plug gage. Make sure that it is firmly mounted and cannot move while being used. 

2) Measure the Reference Point: Use a reference point on your dial indicator or micrometer to zero the measurement. Place a precision-ground Ring Gage at the end of your plug gage and measure it using the dial indicator or micrometer. Record this measurement as your reference point.

3) Measure Each Plug Gage: Measure each plug gage that is being calibrated and record these measurements. Be sure to measure both ends of each plug gage, since they can differ slightly in diameter from one end to the other.

4) Adjust Each Plug Gage if Necessary: If any of your measurements are outside of the tolerance range for size, adjust the corresponding plug gages until they meet their specifications. This can be done by removing material from them with an abrasive stone or by adding material with a welding rod.

5) Record Calibration Results: Record the measurements of all plug gages before and after calibration in your logbook. This will help you track any changes that occur to the gages over time and enable you to quickly adjust them if necessary. 

6) Re-Measure Each Plug Gage: After each plug gage has been adjusted, re-measure it to ensure that it is within tolerance and record these measurements in your logbook as well. 

7) Store Plug Gages Properly: Carefully store the calibrated plug gages in their designated area or container so they are not damaged during use or transport. This will help ensure that they remain accurate and in good condition for future use. 

Measurements Are as Precise as Possible

These steps should be followed every time you are calibrating plug gages to ensure that they remain accurate and reliable over time. Doing this regularly will help you make sure that your measurements are as precise as possible, ensuring the quality of your finished parts. Contact Ledford Gage today for more information.