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CMM Styli and Accessories Technical Data

Technical data is supplied to assist you in understanding our products. If you require additional information please call us at 313.300.0134 or send us an email.


Stylus Anatomy 101

  • dk: Ball diameter

  • ds: Shank diameter

  • D: Ferrule diameter

  • L: Overall length

  • ML: Working length

  • M: Thread

  • Wt.: Approximate weight (in grams)

Drawings are not to scale, please refer to our catalogs for actual dimensions.

Ball and Shank Assembly


Pivot Mount: A drilled ruby ball is glued to the reduced tip end of the shank.


Solid Ball Mount: An undrilled ruby ball is glued directly to the end of the shank .

  • 0.4mm and smaller diameter balls cannot be drilled for pivot mounting

  • Drilled ball / pivot mount designs are recommended for 0.5mm diameter and larger balls for long life and durability.

Advantages of Different Shank Materials

Tungsten Carbide:

  • Sub-micron deflection

  • Small diameter shanks possible

  • Non-magnetic


  • Zero deflection

  • Light weight

  • Easy to see

  • Same Coefficient of Thermal Expansion as the ball

  • Non-magnetic

Stainless Steel:

  • Durable

  • Lowest cost

  • Wide-spread acceptance

Carbon Fiber:

  • Great for high speed machines

  • Light weight minimizes false triggering

  • Use for long stylus configurations

  • Non-magnetic


  • Light weight

  • Maximum strength

  • Highest accuracy

  • Same Coefficient of Thermal Expansion as the ball

Stylus Technical Data

(Scroll down through table to see data for additional materials).

Grade Tolerances Chart / A.F.B.M.A. Standards

(Scroll down through table to see data for additional materials).


  • Grade: The numerical value of the diameter Tolerance per Ball expressed in millionths of an inch.

  • Diameter Tolerance per Ball Sphericity: The permissible difference between the largest diameter and the smallest diameter measurable on one ball

  • Diameter Tolerance per Unit Container: The permissible range on the average diameters of the individual balls within any one container

  • Basic Diameter: The size ordered which is the basis to which the basic diameter tolerances apply. The Basic Diameter is specified by a fraction plus a decimal, or a decimal only, to the sixth place, e.g. 1/4"+ .0002" or .2502" or 15/64"+.0003" or .234675".

  • Basic Diameter Tolerance: The maximum allowable deviation of any ball diameter from the basic diameter, in any shipment to fill orders for that basic diameter

  • Marking Increments: The standard unit steps in millionths of an inch used to express the specific diameter

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