Reference Sphere Setup

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  7.01.002   Geomet 101, 101+, 301, 501 
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Introduction

To add the Reference Sphere to the graphic display of your CMM environment provides a visual enhancement to the CMM measuring area. The process is done by accessing the Define Reference Sphere from the drop down menu [Qualify→Probe System Setup Tools] or through the System Options.

Setting up the Reference Sphere

Reference Sphere Definition AccessTo build the definition of the Reference Sphere, access the setup tool through the Geomet drop down menu, [Qualify→Probe System Setup Tools] and press the <Define Ref. Sphere> button.

Reference Sphere Setup ToolLaunch the Reference Sphere setup tool and the access to all the Reference Sphere parameters will appear.

Choose Standard Holder

Standard SizesThere are three standard Reference Sphere holders produced by Helmel. They can be easily recognized by the reference sphere size.

Selecting one of these standard size also populates several fields in the Parameters group. All fields except the MCS location are provided by the Choose Standard Holder selection.

The default is the 1.0" diameter, 4.375" high holder. 

Reference Sphere Basics

The origin for the Reference Sphere in the Machine Coordinate System (MCS) is the center of the sphere. Under normal conditions, this number is updated when you calibrate your first stylus and it will not be necessary to change the values.

The diameter should be adjusted only when you know a accurate size value for this reference sphere. This value is critical to the overall accuracy of your CMM as every stylus size is determined on the accuracy of this diameter.

Stem Direction IJK

IJK DirectionThe Stem Direction IJK refers to the normal vector direction from the center of the reference sphere through the stem of your reference sphere holder, see example at right.

Under most conditions, the reference sphere is mounted directly to the surface plate of the CMM. All Helmel standard reference sphere and holders are this configuration and the IJK wound be:

I: 0.000
J: 0.000
K: -1.000

Motion Configuration Values

These values refer to Approach Distance, Search Distance, Stem Clearance and Use Stem Data. Under normal conditions, the following recommendations are provided.

Approach Distance : 0.500 (12.7mm)
Search Distance : 0.500 (12.7mm)
Stem Clearance : 0.250 (6.35mm)

The check mark "Use Stem Data" applies these values to the AUto-Calibration function.

NOTE: In Version 7.00.015, the motion characteristics are not active. They have been added in preparation for the next evolution of Auto Calibrate. Currently all motion characteristics will be handled by the standard DCC Settings.

Height Off Table 

This value is important to establish the correct positioning on the surface plate. We suggest to obtain the correct height value, perform the following steps.

1) Start a new inspection.

2) Select stylus number 1.

3) Use the MCS as your active PCS by pressing the ICS→PCS <Shift + "> command.

4) Measure a OD Sphere <v> on the reference sphere.

5) Measure a -Z Point <2> on the top of the surface plate.

6) Obtain the distance between these features by pressing the <s> Keystroke.

Enter this distance value in the cell "Height Off Table".


 

System Options, Surface Plate Definition