Patent pending

CMMs auto-calibration kit



AutoCal is the innovative concept for automatic calibration and accuracy surveillance of CMMs, exploiting the ability of most CNC CMMs to manipulate parts, beside measuring them.

The system consists of four components:

  1. One or more manipulators, easily attached to the touch-probe, mounted on an indexable head like Renishaw's PH10

  2.  A kit of calibrated artifacts, typically rows of ceramic balls on a stable carbon-fiber composite structure

  3. A measuring/manipulating part-program

  4. A specialised SW package for evaluating the measurement results in order to :

    • measure the accuracy of the CMM


    • create a compensation matrix for enhancing the CMMs performances

Operation of AutoCal is very simple:

whenever the user wants to check/compensate the accuracy of the CMM, he will simply mount the special hand on the CMM's head and put at the limit of the measuring volume the tray with the calipers and raisers.

The CMM will automatically pick the calipers and position them at the programmed locations and attitudes and automatically run the proper measuring part program.

If skewed measurements are programmed (e.g. for squareness evaluation), the CMM will automatically position one or more raisers and then tilt the bar in order to lay it at an angle up to 45° to the plate.

A special "ladder" support may be used for vertical measurements.

By means of AutoCal, the user of the CMM can easily keep the machine performances to their best without needing external maintenance and, more important, during the time the machine is not used.

May be used as a very profitable instrument also by CMM Maintenance Professionals

It’s really a 1-2-3 job:

  1. Put the tray with calipers on your CMM plate

  2. Press the button

  3. Forget it

Calibrate your CMM while sleeping!

Download the movie




Evaluation and Calibration S/W
and Artifacts  by
Trapet Precision Engineering


  • The Escalon ball-bar design is an ideal combination of price, weight, stability and transportability, due to the neutral-line arrangement of the spheres
  • Long bars are not needed, due to the use of advanced concatenation algorithms
  • Standard Escalon bars may be employed for CMM verification; more rigid versions for full CMM error mapping
  • The main use of cubes for error mapping is periodical retuning by superimposing low order changes to the old high order error map

Dr. Eugen Trapet