Checking bores with submicron resolution is difficult to do with most handheld gages as human feel impacts the readings. If you want to check those bores while the workpiece is still in the machine the level of difficulty only rises. Today’s applications call for a more accurate solution that is not influenced by the operator taking the reading, one that allows you to sweep the bore looking for signs of taper and ovality as well as size and then record those readings seamlessly.

Since not every application allows a gage to be tethered to a work bench, the Indicating Plug Gage which uses the plug body, not the contacts, to center the gage is another option to consider. It uses an internal probe and needle design that have been perfected over the last 50 years. This style provides two benefits, first the readings are more stable than sweep or triggered gages as the gap between the plug and the part is typically around .001” and the contacts are always in position taking a reading because the body is performing the task of centering the plug.