How Do I Level this Thing?!??

By Mick Capman,
PSFM President (Kalamazoo County Sheriff – Retired)

Ever step up to the tripod and said to your self, oh boy … how do I level this thing again?   

The answer might well depending on who you ask and what their profession is, as some might say there is only ONE way to correctly level the total station.

We offer here one simple solution on how many of us are accomplishing this necessary and all-important task in relative ease. 

We must first appreciate the fact that “accuracy rules!” and that there is no compromise to precise locations of forensic evidence discovered at the scene.

Most recommended electronic total stations are equipped with either a single or double-axis compensator and will not operate (take distance measurements) unless the Instrument is level to within the manufacturers specifications.

Users are encouraged to refer to Instrument manufacturer manuals for these specific configurations.

Most total stations are also equipped with two external leveling bubbles.  One just atop the screen (Sokkia- horizontal, spirit level; Leica- circular bulls eye bubble), and one on the tribrach (bulls eye bubble).

But back to our recommended “simple solution” for this task!

After choosing the R.P./Instruments location, spread the three-tripod legs sufficiently (some recommend a 60-deg.spread) to provide for a good, stable Instrument platform.  Place the Instrument on the tripod’s “faceplate” and tighten the beneath hand-screw sufficiently firm to prevent any incidental Instrument free-rotation.   

Clue:  Position the tribrachs’ bulls eye bubble closest to you. If using a “rotating tripod bracket” as seen here, position this first on the ‘faceplate’ then mount the Instrument on top.

You have undoubtedly noticed on the Instruments lower portion, called the Tribrach (seen here), three (3) knobs.  These knobs when used independently or together affect a change to the “tilt” or “pitch” of the Instruments structure itself.

You should note as well that each knob shaft has a neutral or “common” setting somehow scribed or otherwise noted on the shaft.  This is essentially the “midpoint” for knowing the half-way motion UP or DOWN.

  • Step 1- Set all three knobs to the midpoint, neutral or “common” setting position.

                                    

  • Step 2- Stand squarely between any two sets of tripod legs with Instrument screen facing you.
     
  • Step 3- Using your RIGHT HAND, turn it palm down and place on the tripod leg at point where it telescopes ~ see next picture.  Use LEFT HAND to unlock tripod leg motion and, while watching the bubble on the tribrach, slide/telescope up or down the tripod leg

When bubble is at either the (imaginary) 12 o’clock or 6 o’clock position (see below diagram), lock down the tripod leg motion.

 

 

  • Step 4- Move either to your Left or to your Right, between another two sets of tripod legs, and repeat Step 3 above. When finished, stay positioned here for a moment.
     
  • Step 5-  Now, simply rotate the leveling knob directly in front of you in one direction or the other, to effect the ‘tilt’ of the bubble, placing it exactly in the center position.

If however the bubble appears to slide left or right towards the outside the center ring, use the two ‘distant’ leveling knobs in concert with one another, rotating them together in opposite directions, to effect a ‘pitch’ of the Instrument forcing the bubble towards the center leveling ring.

If your instrument is equipped with a laser plummet (shown above) and once the Instrument is leveled, the precise R.P. location should be marked or otherwise noted.

Once you have leveled the Instrument, it is then time to Zero-SET the Instrument towards a northerly, compass direction, a topic covered elsewhere.

It is fair to note that so long as the Instrument is leveled within a reasonable time ~ that it is leveled to the extent that it permits distance measurements, no matter the procedure to get it level, you should be ready to commence your scene diagramming efforts. 

 
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