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.
Step 2: Making It Functional
I mounted a level on the top platform.
The only thing I had that would work for a scope was a spotting scope for a telescope. I mounted it in the uprights. It works pretty good except that the image is upside down. It takes some getting used to. Ha. Otherwise the only thing left for the transit was a way to determine direction. A compass worked well for that. The transit was ready.
Step 3: Going to Work...
To use the transit you start by placing the tripod on a fairly level space. If necessary you may have to raise or lower a leg or two to compensate for uneven ground. With the transit solid on the tripod and fairly level use the three eybolts to adjust the transit so your measurements are taken properly. Direction is determined by the compass.
A measuring pole can be made from a long pipe or board. I made a 11’ pole by ripping a scrap 2x4 and splicing it together. For the measurement I tacked an old tape measure on it. Then I made a slide so my helper could mark the measurement with the slide if I cannot see the numbers on the rule clearly. The pole turned out a bit heavy so I’ll probably make a shorter one with something lighter.
Using a transit requires a rudimentary understanding of grades, compass direction and measurement. With a bit of patience and work you can plot out the grade of a piece of land accurate enough to determine drainage or how much effort it will take to level the property. Sure saves a lot of money on surveyors and equipment!