WE ARE NOW PRODUCING TWO STANDARD SIZES OF THE MONOLITHIC TRIHEDRAL KINEMATIC COMPONENT. THEY ARE MADE IN THE SURFACE MOUNT DESIGN. THIS TRIHEDRAL IS FREQUENTLY REFERRED TO IT AS A KELVIN CLAMP.

THESE DEVICES ARE CONSTRUCTED FROM A VERY FINE GRAIN, HIGH CARBON, HIGH CHROME STAINLESS STEEL, THAT IS THROUGH HARDENED TO 58 HRC MINIMUM.

THE TYPICAL APPLICATION FOR THIS COMPONENT IS TO CONSTRAIN THREE DEGREES OF FREEDOM IN A KELVIN TYPE KINEMATIC COUPLING. THESE DEVICES ARE THE TECHNICALLY CORRECT APPROACH FOR THIS JOB, WHERE COMMONLY THOUGHT OF CONICAL CUPS ARE A VERY LOW QUALITY OVER CONSTRAINED APPROACH.

IN THIS APPLICATION, THE TRIHEDRAL IS USED IN CONJUNCTION WITH A VEE BLOCK AND A FLAT SURFACE THAT ARE COMBINED WITH THREE BALLS OR SPHERICAL SURFACES, TO COMPLETE THE COUPLING.

THE SMALLEST OF THESE OFF THE SHELF, MONOLITHIC TRIHEDRALS IS OUR PART# TRH-75-SM. IT IS USED IN CONJUNCTION WITH OUR VB-75-SM OR VB-75-CPM ( SURFACE OR POST MOUNTED VEE BLOCK) AND FLXX FLAT COMPONENT (SEE OUR LITERATURE) FOR DESIGN CRITERIA AND THE PRICE. THIS COMBINATION CAN BE USED WITH BALLS RANGING FROM 5/8 INCH (0.625", 15.9 MM ) TO 1.0 INCH ( 25.4 MM ) DIAMETER.

THIS DEVICE HAS A THREE EIGHTS INCH ( 3/8”, 0.375”, 9.525 MM ) 16 THREADED HOLE GOING THROUGH THE CENTER. THIS FACILITATES USING OUT STANDARD 3/8 INCH RARE EARTH MAGNET ( PART# 375-24-MG-N ) TO PROVIDE AN AXIAL PRELOAD (SEE OUT LITERATURE FOR DESIGN CRITERION AND PRICING).

THE LARGEST OF THESE OFF THE SHELF MONOLITHIC TRIHEDRALS IS OUR PART# TRH-2000-SM. THIS IS USED IN CONJUNCTION WITH OUR VB-2000-SM OR VB-2000-CPM (VEE BLOCK) AND FLXXX FLAT COMPONENT (SEE OUR LITERATURE FOR DESIGN CRITERIA AND PRICE). THIS COMBINATION CAN BE USED WITH BALLS RANGING FROM 1 1/4 INCH ( 1.25”, 31.75 MM ) DIAMETER TO OVER 2 INCHES ( 50.8 MM ) DIAMETER. THIS LARGE SIZE TRIHEDRAL HAS A UNIQUE FEATURE, IN THAT THERE IS A ONE INCH ( 25.4 MM ) DIAMETER, THREADED HOLE, THROUGH THE CENTER OF THE BASE. THIS FACILITATES USING OUR STANDARD 1.00 INCH BY 11 ( 25.4 MM ) RARE EARTH MAGNET (PART #1000-11-MG-N) TO PROVIDE A PRELOAD. (SEE OUR LITERATURE FOR DESIGN CRITERION AND PRICING.)

THE HOLE THROUGH THE CENTER OF THIS LARGE TRIHEDRAL ALLOWS FOR A PAYLOAD TO HANG WITH THE LOAD CARRYING SHAFT PASSING THROUGH THE CENTER HOLE.

SOME REASONS FOR USING THE KELVIN TYPE KINEMATIC COUPLING, INSTEAD OF THE MUCH SIMPLER AND LESS EXPENSIVE MAXWELL SYSTEM, CONSISTING OF THREE VEES AND THREE BALLS, IS THAT ONE SINGLE POINT ON THE PAYLOAD MUST STAY IN EXACTLY THE SAME LOCATION DURING TEMPERATURE CHANGES, AND THE OTHER IS THAT ROTARY ADJUSTMENTS NEED TO BE MADE AROUND ONE SPECIFIC POINT. THIS IS A TYPICAL REQUIREMENT IN OPTICAL SYSTEMS WHERE A LASER OR OTHER LIGHT SOURCE MUST BE ACCURATELY AND PRECISELY POINTED OR DIRECTED TO THE OPTICAL AXIS OF A SYSTEM.

THE KELVIN KINEMATIC SYSTEM IS EXCELLENT FOR VERTICAL AND OTHER OFF AXIS KINEMATIC COUPLINGS (SEE VERTICAL KINEMATIC COUPLING IN THE “KINEMATIC ENCYCLOPEDIA” ON WWW.PRECISIONBALLS.COM WEBSITE.

THE SIMPLE COMBINATION OF A TRIHEDRAL AND A VEE BLOCK FORM AN EXCELLENT KINEMATIC HINGE THAT WILL ACCURATELY CONSTRAIN FIVE DEGREES OF FREEDOM, LEAVING ONE SINGLE DEGREE OF ROTATION.