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Ball Plate

icon Features

Short-term Stability

• Stress-free mounting of test object on CMM table

• Reduction of thermal influences through insulated handles

• The test spheres are located in the "non-bending" plane to prevent varying intersphere distances due to changes in position within the measuring volume

• Stable, vibration-free design with sectional frame

Long-term Stability

• The use of high-grade steel and special aging processes ensures exceptional long-term and dimensional stability

• The multisphere standard's symmetrical design prevents testpiece deformation due to variations in temperature.

• The robust design of the multisphere standard and the antivibration lining of its transport container (shock-resistant plastic) make deformation resulting from transport and chucking virtually impossible

• The probing elements are embedded in the test plate for optimum protection

• Only extremely wear resisting and true to form ceramic or steel spheres are used. Furthermore, these elements are also securely precision-inserted in specially developed, deformation-free receptacles

Accessibility of the Probing Elements

• The test spheres are fastened in the multisphere standard in such a way that half of a test sphere can be probed by a spherical probe tip with a diameter 8 mm without restrictions.

• In its upright position, the multisphere test standard can be probed from either side.


• Convenient setup and reconfiguration through a perfected upright positioning system and practical accessories.


• Fast, rational measurement and evaluation using software specially developed by the CMM manufacturer.


• Both the multisphere standard and the probe testing unit can be calibrated either by the PTB (German Federal Physical-technical Institute) or by the DKD (German Calibration Service). This ensures traceability to official master reference standards

icon Probe Testing Unit

• Used for separate inspection of the probe system. Comprises a 30 mm ring gage and a 30 mm ceramic calibration (datum) sphere with holder

• Correct orientation of the face of the ring gage to the multisphere standard is always ensured if the entire holder is shifted 90°

icon Special Designs and Extra Equipment

• Special plate sizes available on request

• Special clamping systems (fixtures) e.g. double frames, 35° clamping system

• Feed (loading) and swiveling systems for manual or automatic inspection

• Multisphere standards made of other materials, e.g. aluminum and invar


*RETTER* Two-dimensional inspection system RP 05

Version Typ MB 300 Typ A MB 400 Typ B MB 600 Typ C
Dimension (mm) 320x320x24 420x420x24 620x620x24
app. weight (kg) 11 18 32
Intersphere distance (mm) 240 (4x60) 322 (4x83) 532 (4x133)
Transport and storage container (WxDxH) 630x600x225 630x600x225 870x810x230

Multisphere test standard

Test sphere Ceramic Steel
Number of spheres 25 25
Sphere diameter 22 mm 22 mm
Sphericity < 0,3 µ m < 1,0 µ m
Material AI203 1,3541
Hardness > 1650 HV 600 - 670 HV
Temperatur expansion coefficient a=5,5 x 10-6°K-1 a=11,5 x 10-6°K-1

Probe testing unit

Ring gage  
Diameter of ring: 30 mm
Shape tolerance: < 3 µm
Temperatur expansion coefficient: a=11,5 x 10-6°K-1
Calibration sphere  
Sphere diameter: 30 mm
Shape tolerance: < 0,15 µm
Temperatur expansion coefficient: a=5,5 x 10-6°K-1
Hardness: > 1650 HV


• Multisphere standard in 3 standard sizes with upright positioning system

• Probe testing unit

• Probe testing unit

• Transport and storage container