Method and apparatus for use in co-ordinate measuring machines

• US 4,168,576 A
• Filed: 01/25/1978
• Issued: 09/25/1979
• Est. Priority Date: 02/07/1977
• Status: Expired due to Term

• Current Assignee: Renishaw PLC
• Original Assignee: Renishaw Electrical Limited (Renishaw PLC), Rolls-Royce PLC (Rolls-Royce Holdings Plc)
• Inventors: McMurtry, David R.
• Primary Examiner(s): Stearns, Richard R.
• Application Number:
  US05/872,312
• Time in Patent Office: 608 Days
• Field of Search: 33/23 K, 33/169 R, 33/172 E, 33/174 L, 33/174 P, 33/174 PC
• US Class Current: 33/559
• CPC Class Codes: G01B 7/008 using coordinate measuring machines
• CPC Class Codes: Y10T 74/1418 Preselected indexed position
• CPC Class Codes: Y10T 74/1476 with means to axially shift shaft

Abstract

In a co-ordinate measuring machine a probe is connected to the head of the machine by a pivotal arm, and the orientation of the probe is changed by moving the head so that the arm engages a fixed structure and a moment is applied to the arm which is thereby caused to turn and present the probe in the required orientation.

Claims

1. A method of operating a co-ordinate measuring machine comprising motor-driven members supporting a head for three-dimensional motion relative to a fixed structure, an arm connected at one end to the head and having a measuring probe at the other end, a pivot connecting said one end of the arm to the head to support the arm for pivotal motion relative to the head, and means providing limited resistance against the pivotal motion;

the method comprising moving the head relative to said fixed structure into a position in which said arm engages said fixed structure at a point on the arm spaced from the center of said pivot, and further moving the head to a predetermined position in the sense causing a moment to be applied to the arm between said point and said center, and overcoming the limited resistance, to turn the arm through a predetermined angle.