renishaw Trigger force User Manual

Leafl et

H-1000-4054-02-B

Trigger force gauge guide

Specifi cation

Overall length 95 mm

Needle length 41 mm

Depth 27 mm

Width 43 mm

Range 4 g to 35 g range with 1 g graduations

Renishaw part no. P-GA01-0001

All Renishaw’s touch-trigger probes have an optimum trigger force
setting for general purpose applications as detailed in table below:

Trigger force

CMM

probes

TP1 (S)

TP2-5 way

TP6 / TP6A

Stylus length

(typical)

31 mm

(PS1-1R)

10 mm

(PS1-2R)

21 mm

(PS1-12R)

Optimum trigger force

(preset by Renishaw)

0.15 N (15 gf)

0.07 N to 0.08 N
(7 gf to 8 gf)

0.11 N to 0.13 N

(11 gf to 13 gf)

Trigger force

range

0.1 N to 0.5 N

(10 gf to 50 gf)

0.07 N to 0.15 N
(7 gf to 15 gf)

0.11 N to 0.3 N
(11 gf to 30 gf)

Trigger force

Trigger force is the amount of pressure applied by the helical
compression spring onto the pivotal plate and bearing points to hold
the stylus mount in place.

The trigger force is preset by Renishaw but can be altered for any of
the following reasons:

• To permit the use of a longer styli on the probe.

• To permit the use of heavier styli on the probe.

• If the preset trigger force has decreased due to probe use.

• If the acceleration of the CMM is causing illegal triggers.

NOTE:

Changing the probe’s trigger force will affect it’s measurement
performance. It is important to requalify the probe confi guration and
check the measurement performance of the probe system after any
adjustment has been made to the trigger force.

Checking trigger force with a Renishaw gram
gauge

1. Ensure that the probe is held fi rmly in position (preferably on a
CMM) and connected to an interface to detect a probe trigger.

2. Establish the direction of trigger which gives the maximum
resistance. The most practical way of doing this is to gently
defl ect the stylus with a fi nger, trying different directions (see
sketch below). There are three lobes which produce three
maximum and three minimum force directions. These can be
easily found with a minimum of practice.

Establishing direction
of minimum resistance

A

B

A = High trigger force direction

B = Low trigger force direction

3. Set the gram gauge maximum force indicator to the zero point
and place fl at on the CMM table. Move the stylus tip to the same
height above the surface as the gram gauge lever.

4. Slide the gram gauge slowly sideways so that the fl at point on
the end of the lever touches the probe stylus ball (ensuring that
the probe is defl ected in the low trigger force direction). Very
slowly continue to move the gram gauge until the probe triggers,
at which point stop immediately, back off the gram gauge and
read the maximum force indicator.

5. Repeat this procedure three or four times to ensure consistent
results.

Measuring
trigger force

NOTE:

Use the following formula to
convert gf to Newtons:

Newtons = gf / 100

Trigger force adjustment

The trigger force of a TP1 (S) / TP2-5W / TP6 / TP6A probe is preset
by Renishaw at an optimal performance setting, but can be altered if
necessary as follows:

1. Remove the probe from the quill of your CMM.

2. Insert the correct size hexagonal key (supplied with every probe)
into the centre of the shank until you locate a grub screw.

3. Adjust this grub screw to alter the trigger force of the probe:

- Clockwise increases the trigger force.

- Anticlockwise decreases the trigger force.

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© 2001 - 2006 Renishaw Issued 0106 Part no. H-1000-4054-02-B