I have had an S6 since around the beginning of 2012.
I used it for many many months without running through the
calibration routines, and found that my vertical angle
got as bad as 57" on sets, my horizontal angle never got much
worse than 15" on the face-2 180.
When I first got the instrument, it wasn't made particularly clear
(or my thick skull didn't absorb),
that the calibration was necessary for the instrument to correct for internal angle error in the instrument electronically and it was not just to come up with the offset correction for how your eyeball and the Autolock view the target.
I recently went through all the calibration routines (sans trunnion), second time
this year, and found my stored values for the vertical correction was about 11"
and about 6-7" for the horizontal.
After two weeks, since the calibration, I'm starting to see up
to 10" horizontal busts in sets and nearly 15" in the vertical.
I have been humping the gun in the case on a few traverses, so that
may have jostled it around a bit and this is where I'm seeing these types of set closures.
Is this amount of error drift typical in that short of a time
span? Is it common to calibrate every week, if you are relying
on the instrument to be accurate for layout in X,Y, and Z?
Does this drift become more rapid as the instrument ages/ is used?
Thanks
>
> Is this amount of error drift typical in that short of a time
> span? Is it common to calibrate every week, if you are relying
> on the instrument to be accurate for layout in X,Y, and Z?
>
> Does this drift become more rapid as the instrument ages/ is used?
>
> Thanks
Aloha, Broken Lath:
I was just going through this routine myself. It is beyond my limited knowledge if the amount of drift is typical. I am sure someone with more experience will post.
Here is what Trimble's user manual says about performing this routines...Hope this helps.
"The Collimation errors and Trunnion axis tilt will change over time, the most common
changes being caused by
• Wear and tear with use
• Bumps and knocks during transit
• Large changes in operating temperature
Trimble recommends that a collimation check and tilt axis check be carried out routinely as
follows:
• After any long uncontrolled transport of the instrument (e.g. after service or shipment to a
new location)
• After any accidental knock or drop
• At any time when the operating temperature changes by more than 10°C (18°F)
• At any time when the instrument changes it's height above sea level by more than 500m
(1640 Feet)
• At any time when the highest accuracy positions are required
• Routinely on a periodic basis (Monthly, weekly etc.)
Trimble also recommends that the operator keep a record of the dates and values measured so
that any gross changes can easily be detected. Gross changes can indicate the need for a
check by an approved service center.
The adjustment of the instrument for HNVA coll imation and Trunnion Axis tilt is a two stage
process.
The Horizontal and Vertical coll imation and the trunnion axis tilt correction have been
measured and stored in the instrument at the factory.
In all calibrations, multiple sightings will be made in both faces to ensure that any minor
pointing errors can be eliminated in the accurate determination of current collimation error
values.
In a new instrument the values should be close to zero, over time these will change. The
instrument allows a maximum value of 0.05 grads (0.045 degrees) in the HA, VA and
Trunnion axis tilt values. If these values are exceeded, the instrument will need service to
rectify a mechanical problem."
You should keep your instrument under warranty and have your trimble authorized/certified dealer for yearly maintenance/repair and calibration
To squeeze the ultimate out of a re-calibration, use some old instruments you have and focus them at infinity and point them towards your S6. Sight on the crosshairs when the S6 is also focused at infinity and your eyeball pointing error will be reduced to aprox. 1"-2". The resulting calibration will then reflect the actual error in your S6 and a whole lot less of your personal pointing error.
The old instruments will be the equivalent of an infinite distance from your S6.
You should not try to do the trunion axis yourself unless you're very sure of and confident in what you're doing. The tilt sensor, Hz collimation and V indexing, and tracker alignment should be performed per the instructions posted by yswami, or any time you either need the best possible accuracy or notice an unacceptable split between F1/F2 measurements.
By the way, it is completely normal for the S6 not to be centered on the prism when autolock is turned on. If you need to feel warm and fuzzy about it do this:
- set up a backsight with a round prism at around 200'
- zero set on the prism with auotolock on
- look through the gun - the crosshair should be noticeably off the center of the prism, this is normal
- while looking through the scope, turn autolock off - you should see the crosshair move to the exact center of the glass if your tracker alignment is good
- check your angles - should have the same values displayed (zero for Hz if you zeroed) as you did when auotolock was on
- while looking through the scope, turn autolock back on - crosshair should move back off the center
- check the angles - should still be the same