Coupling the Stepper Motor to the Threaded Rod
I have found that the easiest way to attach a threaded rod to a stepper motor is with a coupler nut. The coupler nut is prepared by drilling half way through one end with a bit just slightly larger than the shaft of the stepper motor. This way, the coupler can slide onto it.
A small hole is then drilled down through the side of the coupler nut and also into the shaft of the stepper motor. Next, threads are cut into this hole with a tap so that an allen screw can be inserted to keep the coupler nut from sliding off the motor shaft.
With half of the coupler nut attached to the shaft of the stepper motor, the other half screws onto the threaded rod. To keep the coupler nut and threaded rod from separating, a nut is tightened against the coupler so that everything must turn together.
The Pivot Point for the Threaded Rod
The purpose of this part is to attach the threaded rod to the frame of the heliostat while also allowing it to pivot as the machine moves.
First, two holes are drilled half way down through the sides of a coupler nut, each directly opposite the other.
I don’t have exact dimensions for this part, nor do I have a name for it. Basically, it just holds everything together while also allowing the coupler nut to pivot up and down in case of misalignment.
I bolt is placed through the hole in the bottom to give it something to pivot on. This bolt is later screwed directly in to the wood frame of the heliostat.
Finally, the coupler nut is held in the center of this part with two screws that go through its sides and into the holes that were previously drilled into the sides of the coupler nut.
Here are a couple of pictures of the real life version.
Weather Proofing the Stepper Motors
The way I weather proof the stepper motors is to just cut up an empty soda bottle and tape it back together after putting it around the motor. Not very stylish, but it gets the job done.
Stepper Motor Holder
Although it’s difficult to see it through the plastic bottle, the stepper motors are held in place with a piece of PVC pipe that is about 1/3 the length of one of the stepper motors. The motors are wired to the PVC pipe.