I like the nail above door jamb, mark on the floor (preferably with a dimple), and a plumb bob over the pole with bipod.?ÿ Fast, easy, cheap.?ÿ Rarely do you get all three of those together.
There is nothing more?ÿ precise than a total station and a leica circular prism on top of pole. Setup the gun about 20' from the pole. Set the pole on top of a mag nail using a bipod and an adapter for the leica prism, align the boubble with the line from instrument to the pole. Sight the bottm tip of the pole and set Hz angle to 0,?ÿ then sight the prism making?ÿ sure the Hz angle is still 0.?ÿ Make necessary adjustments to the boubble left right until the prism crosshairs coincides with the instrument's.?ÿ Measure the distance and record the number. Turn the pole 180, rotate prism to face the instrument and measure the distance. Adjust the boubble back forward until you read the median value of the 2 distances. Rotate again 180 and check.?ÿ I've managed to set my 8 minute vial this way to 0.4mm runout on a 4' pole. When using the pole extension things change dramatically?ÿ ?ÿbut I believe you could apply the same process for any given pole height, considering the base is concentric with the extension which in my experience is not. That is why my?ÿ pole almast never gets extended.?ÿ
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We have a bracket, with a hole in it the size of the rod, mounted on the equipment store door frame. Plumb under it (set by theodolite) is a plate with a small hole for the rod point. Everytime we go out - slip the rod into the bracket and the point onto the floor plate - check that the bubble is OK. That way you always know it is Ok - checking becomes a quick (20 second) habit
