Kalisphere — Optical Comparator Calibration — Shadow Graph Calibration

The KALISPHERE is a unique device for making a traceable calibration of Optical Comparators or Shadow Graphs. This device has several unique features that are not found in any other system. This calibration artifact is a nearly perfect sphere, of well known and NIST traceable size, mounted on a one inch 1.00” (25.4 mm) square base. The steel balls used on these devices are ultra fine grain stainless steel hardened to 58 HRC and three cycle cold stabilized for long term dimensional stability. What this means is that the diameter of these balls will remain the original size indefinitely.

The extremely uniform surface texture of this well documented sphere has an electro mechanically etched satin finish, that is entirely speckle free. Without the edge reflection of the bright mirror finish typically associated with master balls, the accurate size of the silhouette of the master satin finished ball is micro inch accurate. These spheres are meant for use on shadow graphs only and should never be mechanically probed. Probing these satin finished balls will leave burnish marks that can show up in the image.

In situations where the Kalisphere is used to calibrate machines that are a combination of an optical and a mechanical probe configuration, a satin finished tungsten carbide ball should be used. [See satin finished ball on this website]. The tungsten carbide and the stainless steel balls have the same function, but the T.C. ball costs several times as much. We offer several off the shelf versions, of the “Kalisphere.”

We offer the KS-750-SF, which has a three quarter inch 3/4” (19.05 mm) diameter master satin finished ball for calibration of Shadow Graphs that are used primarily for fractional inch work. The diameter of these balls is 0.75000” (3/4 inch) [19.05 mm] plus or minus 0.000020” (0.5 micron), and they can be N.I.S.T. traceably calibrated for size and sphericity to 0.0000010” ( 0.0000254 mm ), which is one quarter of one micron. This calibration can be documented with a long form certification.

The next “KALISPHERE” is made for calibrating shadow graphs that are used primarily for making decimal inch measurements. The master satin finished sphere used for this application is 0.7000” (17.78 mm) plus or minus 0.000020 inches (0.5 microns). This is our part number KS-700-SF.

The third standard off the shelf Kalisphere is used to calibrate shadow graphs that are primarily used for measuring metric dimensions. This is our part number KS-19-SF. This device has a 19 mm (0.74803”) plus or minus 0.000020 (0.5 micron) exact size and can be calibrated, traceable to NIST to one half of that uncertainty.

The base of the “Kalisphere” is nominally one inch (25.4 mm) square and xxx inch (xxx mm) tall. It is made of a steel that has a high magnetic permeable, which is strongly attracted to a magnet. At the same time this metal will almost spontaneously demagnetize, when the magnetic field is removed. It has very low magnetic retentivity. The design of the Kalisphere allows it to be mounted either vertical or horizontal, to suit the machine being calibrated. It will stand up or it will lie down. See Figure #2. The body of the Kalisphere is black oxide finished to resist rusting.

Rigid mounting of the KALISPHERE is seldom required. A large percentage of the “Kalispheres” that are produced are custom made to the special needs of individual customers. The most common variation of the Kalisphere is special diameter balls, but special elevations of the ball and other variations can also be provided. We can provide special threads or we can provide adaptors to convert our existing M10×1.5 thread design. Metric or English threads of any size can be provided.

See our line of off the shelf “Dual Threaded Adaptor Screws,” to change the thread of the KALISPHERE from M10-1.5 to other situations.

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