Vernier
height gages
are used to mark out lines when accuracy is particular importan
and widely used on surface plates and on machine tables. The
height gage with an indicator attachment is used for checking
locations of surface and holes. The height gage with a scribe
attachment is used to mark reference lines, locations, and stock
allowances on castings and forgings.
Vernier height gauges have a large steel base for stability and a
hardened steel column engraved with inch and mm units. The moving
slide is engraved with vernier calibrations enabling setting to an
accuracy of 0.02 mm and 0.001�? Attached to the moving slide is a
wedge-shaped steel scribe that has a pointed tungsten carbide tip.
The height of the scribe’s point can be finely adjusted with a
thumbscrew.
The method of setting and reading a vernier height gauge is the
same as for other vernier instruments. The work to be marked out
with a vernier height gauge must be set vertically on a surface
plate, using an angle plate.The height of the scribe is set with
the moving slide’s fine adjusting screw. The marking out lines are
then scribe onto the work’s surface by steadily moving the vernier
height gauge along the surface plate (following the same procedure
as for using a surface gauge).On some vernier height gauges, the
height of the main scale can also be finely adjusted. This enables
measurements to start from a convenient reading, which is useful
if the shape of the workpiece is such that it needs to be mounted
on a parallel strip .Note that digital height gauges are now
becoming more common as they are much quicker to set up and more
accurate to set.
Precision vernier height gauges must be stored in their original
packaging case and should be carefully used and maintained. If you
suspect that the instrument is inaccurate, it must be reported to
your fault, so a ‘back footed�?approach could prove to be
appropriate.