The challenge: determine the grade of our back yard for a pond.
The problem: I’m broke
The solution: a home-made transit that I can use to shoot a grade.
A transit does a simple thing. It looks strait across a space to a ruled pole. Commercial transits use a scope with magnification in order to read the ruled pole held by an assistant. The scope has to be level . It must provide a way to show direction/bearing. If I could figure all that out I had a tool I could use.
Step 1: Basic Construction
In making a transit the complicated part comes in making sure the view is straight across, level, and in measured directions. I had to build something that would fit on a tripod, sit level, provide a strait-line view preferably with magnification. Finally, it had to determine direction or bearing.
To begin I would need a base that mounts on the tripod and then a platform to hold the scope. Then there would be a secondary platform that is adjustable so that it is level. That means the upper platform had to somehow sit above the lower one on a pivot point and have some way to indicate direction. The latter I left to last. The rest I figured out as I went along.
I cut a base out of a piece of particleboard shelving for the base. It was circular, about eight inches. I cut another piece for the second platform about an inch smaller. To mount the base on the tripod I drilled a hole in the center of the base and put in a ¼” bolt anchor in it for the tripod bolt. I used part of an outdoor light fixture with an oval shape to provide a means of pivoting the second platform. The top platform fastens to the bottom by passing a bolt through a hole in the center of the top platform and into the top of the anchor. I used an eye bolt so it would be easier to tighten.
I drilled three holes in the upper platform and inserted anchors through which I screwed ¼” eyebolts. This allowed the top platform to be adjusted in three directions. For the scope mount I cut a couple of uprights out of pine with notches to hold the scope. I mounted the uprights on the top platform and put screws through the sides to hold the scope.