SH25 stylus holder range metrology performance

SH25-2A, SH25-3A and SH25-4A have distinct metrology advantages over SH25-2, SH25-3 and SH25-4 for any stylus arrangements where the stylus holder is subjected to torsional load when using components like cranked styli or knuckle joints.

The standard range of SH25 stylus holders still have an advantage over the -A range of stylus holders when straight styli arrangements are required.

The following tables compare typical metrology performance with the standard and -A range of SH25 stylus holders for both straight and cranked stylus configurations.

SH25-2 against SH25-2A - bi-directional ring gauge scan test

Straight stylus perfromance - effective stylus reach 51 mm:

 

Stylus holder

SPAN data raw

SPAN data filtered

Stylus tip deflection

SH25-2

1.6 µm

1.2 µm

0.2 mm

SH25-2A

1.5 µm

1.1 µm

0.2 mm

Cranked stylus performance - crank down distance 55 mm, crank out distance 83 mm:

 

Stylus holder

SPAN data raw

SPAN data filtered

Stylus tip deflection

SH25-2

14.9 µm

5.9 µm

0.35 mm

SH25-2A

4.1 µm

2.4 µm

0.35 mm

SH25-3 against SH25-3A - bi-directional ring gauge scan test

Straight stylus perfromance - effective stylus reach 121 mm:

 

Stylus holder

SPAN data raw

SPAN data filtered

Stylus tip deflection

SH25-3

2.2 µm

1.3 µm

0.2 mm

SH25-3A

2.5 µm

1.7 µm

0.2 mm

Cranked stylus performance - crank down distance 125 mm, crank out distance 83 mm:

 

Stylus holder

SPAN data raw

SPAN data filtered

Stylus tip deflection

SH25-3

11.8 µm

8.2 µm

0.35 mm

SH25-3A

3.5 µm

2.1 µm

0.35 mm

SH25-4 against SH25-4A - bi-directional ring gauge scan test

Straight stylus perfromance - effective stylus reach 221 mm:

 

Stylus holder

SPAN data raw

SPAN data filtered

Stylus tip deflection

SH25-4

3.0 µm

1.7 µm

0.2 mm

SH25-4A

3.5 µm

2.4 µm

0.2 mm

Cranked styus performance - crank down distance 225 mm, crank out distance 83 mm:

 

Stylus holder

SPAN data raw

SPAN data filtered

Stylus tip deflection

SH25-4

15.7 µm

5.0 µm

0.35 mm

SH25-4A

5.1 µm

2.4 µm

0.35 mm

Test setup criteria

Test site

Renishaw UK

Styli used

Renishaw's M3 stylus range

CMM specification

U3 = 0.48 µm + L / 1000

CMM controller

Renishaw's UCC2

Probe calibration

Renishaw's third order polynomial calibration method

Data filter used

Harmonic simple cut off order = 60 UPR (undulations per revolution)

Artefacts used

Ø25 mm (nom) calibration sphere (for the ISO 10360 Part 2 / Part 4 tests)
Ø50 mm (nom) ring gauge (for the ring gauge scan tests)

Scanning speed

5 mm/s (for the ISO 10360 Part 4 and ring gauge scan tests)

Touch speed

5 mm/s (for the ISO 10360 Part 2 tests)

Back off speed

1 mm/s (for the ISO 10360 Part 2 tests)

Bi-directional scans

The effect of probe misalignment and contact friction will result in radius changes with scanning direction if a suitable calibration procedure is not used.

Mechanical hysteresis within a probe mechanism is best demonstrated by a bi-directional scan.

Therefore, Renishaw have decided to take the high integrity approach of quoting ring gauge metrology using bi-directional scan data to demonstrate the performance of the Renishaw probe and calibration method.