INDUSTRIAL MONITORING INSTRUMENTATION DIVISION
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introduction
Spot face tools are used to create a flat circular surface to mount an accelerometer. Each
model has an installed center drill that is the correct tap drill for tapping a ¼-28 UNF-2B thread.
installation
Obtain a hand drill motor and install the shank end of the spot face tool into the chuck of the
drill motor. Tighten the chuck and check the direction of rotation. The rotation should be
counter clockwise when looking at the chuck end of the drill motor.
operation
Choose the area on the surface where the accelerometer is to be installed. Using a center
punch, mark the spot of the center of the accelerometer. Apply a small amount of light oil to
the surface to be used as a cutting fluid.
Apply the point of the center drill on the spot face tool to the center punch mark, grip the drill
motor firmly and begin drilling.
The drill motor should be kept as perpendicular to the axis that is going to be measured as
possible. Often on castings and molded parts the axis is not necessarily perpendicular to the
surface being prepared. A cross-check or torpedo level is very helpful in determining
perpendicularity.
The revolution speed of the drill motor should be kept between 150 and 350 RPM to optimize
the life of the tool. Allow the tool to do the cutting. Do not apply excessive pressure while
drilling, this will accelerate tool wear. The addition of a lubricant or cutting fluid during the
cutting process will also greatly increase tool life.
