The great quadrant is finished.
Today’s first task was adding the screws to the base to allow the instrument to be more easily leveled. To do this, we used some antique Jorgensen wood clamps. These provided the threaded dowels with handles as well as matching threads. The threads were glued and screwed to the underside of the base.
The handles would then be threaded through this and set on a foot approximately 3″ square. These feet had a small divot drilled in them to allow the rods to fall into them easily.
However, raising the base to adjust the leveling caused a slight problem; the posts that make up the legs could simply slide through the base thereby not actually fixing the issue. To resolve this, We added some supports on the sides of the posts that prevented them from sliding down further even when raised off the ground.
The final task of the day was to add the sights. This is one of the things that I intend to experiment with the most as there are several ways the sights could be set up. For our first attempt, we went with a very simple rifle style sight. To create them, we used some steel angle brackets that we cut down.
Once they had a good short end to sight down, we cut notches in them.
We took great care to ensure that the depth of each notch was nearly identical as not sighting parallel to the arm would introduce systematic error. However, if the sights were off by $\frac{1}{16}$” this would introduce an error of 0.01º or 0.6 arcminutes. Since I’m hoping for a resolution of 3-6 arcminutes, this is an order of magnitude below the detection threshold so shouldn’t be too big an issue.
Ultimately, I think they’ll work just fine. It was hard to get them lined up while also holding a camera, but they felt fairly easy to use.
We also swapped out the neon orange cord for the plumb with some leather lacing I had around. Not only does this provide a better look, it’s much more narrow allowing for a finer reading.
In the test setup we did, I did discover just how easily any perturbation causes the plumb bob to start swinging. Since it’s connected to that plumb line, that means that it’s hard to take a measurement. Just how big a problem this is remains to be seen.