Apparatus for scribe engraving a workpiece with a miniature representation of a two-dimensional pattern in response to movement of a stylus following the pattern includes a spherically rotatable member having a frusto-spherical surface rotatably retained within a frusto-spherical bearing race remote...http://www.google.es/patents/US4687390?utm_source=gb-gplus-sharePatente US4687390 - Engraving apparatus having improved bearing and pattern
Engraving apparatus having improved bearing and pattern
