FOR CALIBRATING STANDARD VERTICAL OR HORIZONTAL C.M.M. PROBES, OUR LONG TIME STANDARD PROBE CALIBRATION SPHERE, PART NUMBER PM-PB-B100 IS THE BEST INEXPENSIVE SOLUTION.

WHEN YOU MUST CALIBRATE COMPLEX STAR PROBES OR ARTICULATING PROBES, THE LONG TIME STANDARD PROBE CALIBRATION SPHERE COMES UP LACKING; BECAUSE THE LARGE RIGID POST WE USE COVERS UP TOO MUCH OF THE AREA OF THE PROBE CALIBRATION SPHERE.

MOST COMPETITIVE COMPANIES HAVE TRIED TO SOLVE THIS PROBLEM BY USING SMALL DIAMETER OFFSET POSTS. THIS APPROACH CAUSES MORE PROBLEMS THAN IT SOLVES. THIS IS ESPECIALLY TRUE WHEN THESE POSTS ARE MADE OF VERY LOW STIFFNESS STAINLESS STEEL. THE BENDING OF THIS SPINDLY POST BY THE PROBING FORCE CAUSES THE SPHERE TO MEASURE MUCH SMALLER THAN IT REALLY IS. WHEN THE PROBE IS COMPENSATED, USING THE TRUE DIAMETER OF THE CALIBRATION SPHERE, A SUBSTANTIAL ERROR IS BUILT INTO EVERY FUTURE MEASUREMENT.

THE SLIM CALIBRATION SPHERE SOLVES THESE PROBLEMS QUITE NICELY. THIS IS DONE BY MOUNTING THE PROBE CALIBRATION SPHERE ON A VERY SMALL DIAMETER ROD OF AN EXTREMELY RIGID MATERIAL.

BY USING THIS VERY SIMPLE FUNDAMENTAL OF PHYSICS, WE GET EXCELLENT ACCESSIBILITY WITHOUT THE ELASTIC DEFLECTION CAUSED BY THE PROBING FORCE. BY BUILDING THE SUPPORT ROD FROM A MATERIAL THAT IS ALMOST FOUR TIMES AS STIFF AS HARDENED STEEL, OUR ONE EIGHTH OF AN INCH DIAMETER ( 3.175 MM ) SUPPORT ROD IS EQUIVALENT TO A .400-INCH ( 10.16 MM) DIAMETER STEEL POST.

THE RUGGED ONE AND ONE QUARTER INCH (31.75 MM) DIAMETER CONSTRUCTION OF THE SLIM CALIBRATION SPHERE BASE IS COMPATIBLE WITH ALL OF OUR PROBE SPHERE HARDWARE. THIS INCLUDES ALL EXTENSIONS, BASES AND THE 45-DEGREE BLOCK. IT IS HELD IN PLACE BY A LARGE M10 X 1.5 (OVER 3/8 INCH) SOCKET HEAD CAP SCREW. THIS ARRANGEMENT ALLOWS THE SPHERE OR SPHERES TO BE ROTATED INTO THE IDEAL POSITION FOR PROBING BEFORE LOCKING THE ASSEMBLY DOWN.

THE SIMPLEST VERSION OF THE SLIM CALIBRATION SPHERE (OUR PART NUMBER PM-SLM-) FOLLOWED BY THE DESIRED DIAMETER OF THE CALIBRATION SPHERE REQUIRED (1 INCH, 20 MM, .5 INCH, 10 MM ETC.), AT A COST OF BETWEEN $182.42 AND $199.45 EACH.

THE SIMPLEST DESIGN HAS A SINGLE MASTER SPHERE MOUNTED AT 45 DEGREES ON A ONE-INCH (25.4 MM) LONG, ONE EIGHTH OF AN INCH (1/8", 0.125", 3.175 MM) DIAMETER EXTREMELY STIFF ROD.

THIS DEVICE IS ALSO AVAILABLE WITH UP TO FOUR CALIBRATION SPHERES MOUNTED SIMULTANEOUSLY. SIMPLY SPECIFY THE DIAMETERS OF THE DESIRED SPHERES WHEN ORDERING (EACH ADDITIONAL SPHERE COSTS $86.19 EACH). THE CALIBRATION SPHERES CAN ALL BE OF THE SAME DIAMETER, OR THEY CAN BE OF DIFFERENT DIAMETERS.

IN VERY SOPHISTICATED C.M.M. SYSTEMS, TWO MASTER SPHERES OF EXACTLY THE SAME DIAMETER, LOCATED 180 DEGREES APART, ARE USED TO CALIBRATE THE PROBE. THE DISTANCE BETWEEN THE TWO SPHERES IS FIXED, SO IT CAN BE SUBTRACTED WHEN BOTH SPHERES ARE PROBED. IN THIS WAY THE AREA WHERE THE POST IS LOCATED DOES NOT SUBTRACT ANYTHING FROM THE CHARACTERIZATION OF THE PROBE.

WHEN CALIBRATING REALLY SMALL DIAMETER PROBING TIPS, THERE IS A DISTINCT ADVANTAGE IN USING A MUCH SMALLER DIAMETER PROBE CALIBRATION SPHERE. FOR THESE APPLICATIONS A 10 MM (.3937 INCHES) OR THREE EIGHTHS OF AN INCH (9.53 MM) SPHERE IS THE USUAL CHOICE. BECAUSE THESE SMALL DIAMETER SPHERES ARE SO EASILY DAMAGED, THEY ARE NORMALLY CONSTRUCTED OF CEMENTED TUNGSTEN CARBIDE.