Renishaw P-GA01-0001 User manual

Leaflet
H-1000-4054-02-B
Trigger force gauge guide
Specification
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
Stylus length
(typical)
Optimum trigger force
(preset by Renishaw)
Trigger force
range
TP1 (S) 31 mm
(PS1-1R) 0.15 N (15 gf) 0.1 N to 0.5 N (10 gf to 50 gf)
TP2-5 way 10 mm
(PS1-2R)
0.07 N to 0.08 N
(7 gf to 8 gf)
0.07 N to 0.15 N
(7 gf to 15 gf)
TP6 / TP6A 21 mm
(PS1-12R)
0.11 N to 0.13 N
(11 gf to 13 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 configuration 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 firmly 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
deflect the stylus with a finger, 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.

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Renishaw worldwide
© 2001 - 2006 Renishaw Issued 0106 Part no. H-1000-4054-02-B
3. Set the gram gauge maximum force indicator to the zero point
and place flat 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 flat point on
the end of the lever touches the probe stylus ball (ensuring that
the probe is deflected 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.
Establishing direction
of minimum resistance
A = High trigger force direction
B = Low trigger force direction
A
B