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Taking measurements with MCG

Taking measurements when using MCG Tools

Renishaw have simplified the implementation of using an MCG by providing on-line MCG Tools on the Renishaw website:

www.renishaw.com/mcg

Using the MCG has never been easier with Renishaw's online MCG service.  In three easy steps, we help you to measure, analyse and track the volumetric performance of your CMM:

  1. Create an MCG test program to run on your CMM - a DMIS program is generated for you from a set of parameters that you specify.  You can run this on your CMM to generate a set of measurement results.
  2. Analyse your MCG test results - the MCG test generates a set of measurement results, again in DMIS format.  You can upload these and have them analysed online.  We provide guidance to help you interpret the data.
  3. Store and retrieve previous results to spot trends - you can store your MCG test results online and retrieve them at a later date, allowing you to identify changes in the performance of your CMM over time.

Taking measurements when not using MCG Tools

  1. Arm elevation 0° - measure the arm radius R at 45° intervals in the horizontal plane (a total of eight measurements).
  2. Arm elevation -45° - measure the arm radius R at 45° intervals in the horizontal plane (a total of eight measurements).
  3. Arm elevation +45° - measure the arm radius R at 45° intervals in the horizontal plane (a total of eight measurements).
  4. Repeat steps 1 to 3 twice to obtain repeatability measurements.  This provides a total of 72 (3 × 24) measurements for evaluation of volumetric measuring performance and system repeatability.
  5. Remove the counterbalanced arm carefully and re-datum the pivot ball using a minimum of ten readings (refer to the ‘Setting-up' section).  If the pivot ball centre has moved significantly more than the maximum measured repeatability, re-datum the pivot ball ensuring that:
  • The seating faces between the pivot , pillars and baseplates are perfectly clean and that these parts are firmly tightened.
  • The stated pillar thermal stabilising period (2 minutes minimum) is observed.
  • The utmost care is taken when placing the counterbalanced arm of the pivot.

Arm elevation:

MCG arm elevation

Eight points of measurement:

Eight points of measurement for MCG