NavList:

A concrete pillar was a perfect choice. Did you custom build a mounting plate for the pillar? Your back sight doesn’t have to be “north”, I would use the most distant object visible from your pillar…. A distant tower, building, etc… If you used a nail for your 100 yard back sight, I would keep the original nail and add new nails as you refine your north (hopefully your fence post is not bumped by livestock). With multiple “north” front sight nails, you can test each nail over the course of a year. Mistakes in your method of setting up the instrument should become apparent. Use the exact same sequence of steps each time you set up the instrument. For example, always align the crosshairs on the back sight from the same direction. Aim the scope above and to the right of back sight, then align the crosshairs toward the nail (or whatever). Always use above and to the right. Theodolites usually have some play in the action. After becoming familiar with your instrument’s quirks, you will know if that play is to the above right, above left, lower right, or lower left. Some newer total stations have plastic worm gears; the plastic gears have a lot of play.

-----Original Message-----
From: NavList@fer3.com [mailto:NavList@fer3.com] On Behalf Of Richard Gaarden
Sent: Saturday, October 12, 2013 8:52 AM
To: george@gwbeckerpls.com
Subject: [NavList] Re: Unrealistic expectations

: http://fer3.com/arc/m2.aspx?i=125302