Difference between revisions of "New site and tripod setup description"

From GeodesyLab
Jump to: navigation, search
Line 57: Line 57:
 
</tr>
 
</tr>
  
 +
<tr>
 +
  <td>'''8.'''</td>
 +
  <td>loosen tribrach using the hollow screw and the steer the dot in the sight over to within 1 cm of center punch on marker.
 +
  </td>
 +
  <td>Take your nail w/ pre-existing punch mark or small drill hole in head. One person pounds nail into ground while other person guides its placement - centered under the leveled tripod.</td>
 +
</tr>
  
 +
<tr>
 +
  <td>'''9.'''</td>
 +
  <td>re-level the tribrach bulls-eye by adjusting the leg length. </td>
 +
  <td>celebrate the new benchmark.</td>
 +
</tr>
 +
 +
<tr>
 +
  <td>'''10.'''</td>
 +
  <td>confirm still centered near the punch mark in view.</td>
 +
  <td>celebrate a little more.</td>
 +
</tr>
 +
 +
<tr>
 +
  <td>'''11.'''</td>
 +
  <td>fine tune the leveling of long level bubble on optical plummet:<br/>
 +
1. align bubble between 2 tribrach knobs and level it by turning knobs equally and in opposite directions.<br/>
 +
2. rotate optical plumb so long level bubble is at 90° to previous measurement.<br/>
 +
3. use the 3rd knob on tribrach to level it.<br/>
 +
Note: note directions on opt. plumb for bubble adjustment!
 +
</td>
 +
  <td>same.</td>
 +
</tr>
 +
 +
<tr>
 +
  <td>'''12.'''</td>
 +
  <td>rotate optical plumb by 180° ti see if long bubble is correctly balanced. If not then split the difference back towards the center so the bubble is off by the same number of ticks (e.g. to the left) at 180° opposite orientations of optical plumb.<br/><br/>
 +
For example a badly balanced bubble might be level wehn it is 2 ticks off to the left (as you face the bubble).
 +
<br/>
 +
</td>
 +
  <td>same.</td>
 +
</tr>
  
 
</table>
 
</table>

Revision as of 21:18, 27 May 2008

  pre-existing site new site
1. extend tripod legs equally to chest height. same.
2. adjust tribrach knobs to reference line. same.
3. fasten tribrach onto middle of the tripod head. place entrire tribrach/optical plumb on tripod.
4. use tribrach to position tripod correctly over marker by satisfying the following 3 conditions:

1. bulls eye level bubble is level
2. you can look down through hollow screw and see marker
3. all tripod feet are on ground.
(Note: this is the most tricky, but if carefully done most rewarding step for everything that follows.)

spread tripod feet out @ 1 m separation and locate them so that tribrach is level.
5. With leg clamp loose, stomp tripod feet firmly in soil (stabelize with rocks if necessary) same.
6. roughly level tribrach again by adjusting tripod leg length. same.
7. attach optical plumb to tribrach and focus 2 things:

1. focus large knob on marker
2. focus small knob for black ring sign.
both should be sharp and in focus.

same.
8. loosen tribrach using the hollow screw and the steer the dot in the sight over to within 1 cm of center punch on marker. Take your nail w/ pre-existing punch mark or small drill hole in head. One person pounds nail into ground while other person guides its placement - centered under the leveled tripod.
9. re-level the tribrach bulls-eye by adjusting the leg length. celebrate the new benchmark.
10. confirm still centered near the punch mark in view. celebrate a little more.
11. fine tune the leveling of long level bubble on optical plummet:

1. align bubble between 2 tribrach knobs and level it by turning knobs equally and in opposite directions.
2. rotate optical plumb so long level bubble is at 90° to previous measurement.
3. use the 3rd knob on tribrach to level it.
Note: note directions on opt. plumb for bubble adjustment!

same.
12. rotate optical plumb by 180° ti see if long bubble is correctly balanced. If not then split the difference back towards the center so the bubble is off by the same number of ticks (e.g. to the left) at 180° opposite orientations of optical plumb.

For example a badly balanced bubble might be level wehn it is 2 ticks off to the left (as you face the bubble).

same.
Retrieved from "http://gps.alaska.edu/internal/index.php?title=New_site_and_tripod_setup_description&oldid=547"