A small dial instrument whose pivoting stylus moves sideways, reading to half a thou or a tenth per division. It is the tool for indicating vises, sweeping bores, tramming heads and comparing heights on the surface plate. It reads true only when the stylus is roughly parallel to the surface; at an angle it reads high, and the true movement is the reading times the cosine of the angle, so it is used for comparison rather than absolute measurement.
Put the test indicator on the jaw and run the table, I want the vise within a half thou over the full length.
Keep the stylus close to parallel with the surface; tilt it 30 degrees and the dial already reads about 15 percent high.
Also heard as
- DTI
- dial test indicator
- lever indicator
- Last Word
Related terms
Indicate
To align a vise, part or bore to the machine axes using a dial or test indicator.
Sweep
To rotate an indicator in the spindle around a bore, boss or circle to find its center or check alignment.
Tram
To square a mill head or spindle to the table so the spindle axis is truly perpendicular.
Surface plate
A thick slab of granite or cast iron, lapped flat, that every height check and layout line is measured from.