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Hall Experimental M3 Tripod Produced in the 1920's

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Designed By:
Rupert E. Hall
Manufactured By:
Rupert E. Hall
US Patent:
Patent Date:


This is an example of one of Rupert Hall's experimental “Tripod” type articulators. Hall left no known instructions for its use. The condylar controls are unique in that the condylar balls rest in an open 45 degree V-shaped slot, open ended in the posterior and with a centric stop (in the shape of a ball) at the anterior end. This mechanism rests on a disc that moves horizontally, presumably to set the Bennett movement. It is odd that there the capability for the condylar balls to travel backward and downward and for the horizontal disc to carry the V-shaped slot outward. The incisal pin locks into an offset hole in a flat pulley table that produced an elliptical movement when turned. There were most likely other incisal tables made for this instrument, but none are known.

JP Articles

Side view
Side view
This posterior view shows the V-shaped condylar slots.
Close-up of a condylar control.
Detail of a condylar control showing the upper ball in place against the ball-shaped stop.
Close-up of the incisal pin in the offset hole in the incisal (pulley) table.

Dr. Edgar N. Starcke's articles in the Journal of Prosthodontics have more information on the history of articulators.