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 (528) 759-2400 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