St. Mary Rotary “V” Block Gage

The precision St. Mary Rotary “V” Block Gage makes measuring concentricity characteristics on cold headed parts faster. easier, and more precise than other similar devices.

Geometric tolerancing measurement requirements are becoming more common on fasteners and cold formed specials.

size diameters between the rolls: Unit will hold as small as .062″, and as large as 1.25″ diameters.  Larger ones available

St. Mary Rotary “V” Block Gage Features:

  • It is vital for fastener producers to have the capability to make these geometric, relational measurements accurately and repeatably
  • The St. Mary gage design derives its accuracy and repeatability from its patented intermeshing three part contacting roll design.
  • Other features contributing to its precision are an adjustable length stop, and adjustable spring loaded hold-down arm, sealed bearings, and lapped contact rolls
  • On the smallest gage model, concentricity measurements as precise as .00005 inches can be made

concentricity gage

1. Rotate the knob on the left counterclockwise to open the rolls enough to fit the fastener being checked.
2. Place the sample screw between the rolls, and rotate the knob clockwise to tighten the rolls onto the screw
3. Loosen the thumb screw on the indicator arm and position the indicator point immediately over the point at which the part is to be measured and tighten the thumb screw to fix the indicator into position.
4.Press the ZERO/ON button. If the indicator is not in the desired increments press the IN/MM button to change from inches to millimeters or millimeters to inches
5. Press the RAN (Range) three times to put the indicator into the “TIR/FIM mode
6. Rotate the fixture handle three times in each direction. The value on the display is the “Total Indicator Reading or the “Full Indicator Movement. Note: “Concentricity is ½ of TIR/FIM.
7. To remove the screw, rotate the know on the left of the fixture counterclockwise until the screw is released. Remove the screw and place the next sample in the fixture.

Measuring Perpendicularity (optional)
1. Change over the plunger style indicator to a test indicator of your choice. The fixture will accommodate a 3/16 holder stem. Additional post shown in picture below is provided.
2. Perform the above procedure for loading the fastener. Locate the stylus of the test indicator to the face you are trying to measure and rotate the handle to observe total indicator movement.



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