Adjustable diameter pneumatic comparator for measuring bore diameters

A pneumatic comparator probe system comprising:

• a pneumatic comparator probe that includes:
• a probe body configured to contact a bore to be measured;
• a variable separating mechanism moveably connected to the probe body;
• and
• a measuring component that contacts the variable separating mechanism, the measuring component including a port through which pressurized air passes when the pneumatic comparator probe is in use;
• wherein movement of the variable separating mechanism adjusts a position of the measuring component in a direction of diametrical expansion relative to the probe body;
• a gage unit that supplies the pressurized air to the measuring component and includes:
• a rigid framework to which the probe body is connected;
• a movable measuring carriage, where the measuring component is attached to the measuring carriage;
• and
• a control system that measures a characteristic representative of a flow rate of the pressurized air and determines a diameter of the workpiece at the location by comparison to one or more master rings having a known inside diameter.

A method of measuring a bore size of a workpiece, the method comprising:

• providing a pneumatic comparator probe system, wherein the pneumatic comparator probe system includes:
• a pneumatic comparator probe that includes:
• a probe body configured to contact a bore to be measured;
• a variable separating mechanism moveably connected to the probe;
• and
• a measuring component moveably connected to the probe body that contacts the variable separating mechanism, the measuring component including a port through which pressurized air passes when the pneumatic comparator probe is in use;
• a gage unit that supplies the pressurized air to the measuring component;
• a rigid framework to which the probe body is connected;
• a movable measuring carriage, where the measuring component is attached to the measuring carriage;
• and
• a control system that measures a flow rate of the pressurized air
• placing a workpiece to be measured on to the pneumatic comparator probe system such that a surface of a bore of the workpiece rests on the probe body at a location such that the bore contacts the probe body at a location that is diametrically opposite from the port of the measuring component;
• supplying pressurized air by the gage unit to the port and passing the pressurized air through the port;
• measuring by the control unit a characteristic representative of a flow rate of the pressurized air passing through the port;
• measuring by the control unit a characteristic representative of the position of the measuring component relative to the probe body;
• and
• determining by the control unit the diameter of the workpiece at the location by comparison to one or more master rings having a known inside diameter.