Contours, radii, and other special shapes can be ground by forming the reverse geometry on the grinding wheel. Various methods are used for this. Using a radius dresser that swings the single-point diamond in a preset arc is one method. The wheel dressing pantograph (Figure L-59) can form dress a vitrified grinding wheel to almost any shape. Note that with radius and form dressing the process trues and dresses the
grinding wheel simultaneously.
In crush roll dressing (Figure L-60), the form is literally crushed into the wheel by a carbide or diamond roll. Crush dressing is used on both surface and cylindrical grinders.
Crush roll dressing results in a very sharp, free-cutting grinding wheel that leaves a less burnished finish than a diamond dressing.
For this reason the wheel must be an accurate match for the grinding to be done. The roll must be mounted solidly to withstand the pressures involved (Figure L-61).
Using a diamond dressing block is another way of form dressing a wheel (Figure L-62). Machines suitable for crush dressing applications are typically of either roller bearing or hydrostatic spindle bearing construction to resist the intense forces involved.
