Here is an assortment of pictures of a linear actuator based heliostat that I put together. I am thoroughly convinced that a linear actuator based machine isn't really the best way to go since they are more complicated and have a rather limited range of motion, but I wanted to have at least one machine around to help with testing the Sun Tracking / Heliostat Program's linear actuator settings. I'm glad I did too because I did find one bug.
I will update the fixed version of the program soon
(already done), but in the meantime I figure that I can at least show what I have been up to.
Overall, the machine does seem to track well,
but it is painfully slow
(Nevermind, I tried it out at a higher speed, and it looks like the stepper motors can move the machine at a much higher speed without losing steps), which seems to be typical with the linear actuator based machines.
Here is a picture of the front of the heliostat. I haven't even bothered to clean the mirror yet since this is just a quick test.
Here is the back of the heliostat. I don't know if you can see it very easily, but instead of using door hinges for the alt rotation, I instead used galvanized lag screws as a pivot. I figured that they would hold up a lot better in the weather and are probably cheaper too.
It is a lot easier to align a machine to the correct azimuth direction if you are able to rotate the entire thing to point at the sun in sun tracking mode and then lock it into place to keep it there. Forget about that nonsense I have suggested in the past about using a compass for alignment, this is waaay easier. I have decreed it, all heliostats and sun trackers shall hence forth be designed with this ability built in.
It's probably hard to see this in the below picture, but the 2x4 sitting on top of the 4x4 post is screwed down so that it can't move. The 2x4 on top of it is clamped to the pipe, and the pipe is able to turn inside of a hole drilled into the 2x4 on the post. So the entire machine, leadscrews and all, rotates around the azimuth pivot point.
Here is a view from the side. Perhaps you can see the lagscrew better here.
Here is a view looking down on the leadscrews. None of the electronics are really protected from the rain since the machine is just temporarily set up for now.
If you want to get a closer look at how everything has been put together, here is the link to the Sketchup model. It's not exact, but it is close. I believe there are some errors, in particular where the mirror interferes with the 2x4s that are on top of the post.www.cerebralmeltdown.com/forumpics/LinHelio/LinearActuatorHelioV11.skp
Anyway, enough of that machine and on to bigger and better (well at least better) things. Like I said, worm gear based heliostats are a lot easier to understand. When using linear actuators, there are at least 6 more variables that have to be taken into consideration, and if you make a mistake on any one of them, your machine isn't going to work and you'll inevitable spend hours of your life trying to figure out why.
I don't have a lot to show yet as I've spent most of my effort experimenting with the design in Sketchup. It is still basically a variation of the design of the machine that I posted at the top of this thread. You can download the model at the below link if you want to see what I have so far.www.cerebralmeltdown.com/forumpics/LinHelio/HeliostatV51.skp
Here is one picture of a mock model. This will never actually be completed as I just wanted to get a rough idea of the scale and the machine's rigidity.
The worm gears actually weren't very difficult to make. I think the method I used might have been similar to the one Jim used for his machine. http://cerebralmeltdown.com/forum/index.php?topic=293.0
For the worm part of the worm gear, I used 7/16-14 threaded rod. For the actual worm gear, I cut a circle out of some scrap plastic with a hole saw and then mounted it in a jig that it was able to rotate on. I then cut a groove around the perimeter of the circle by drilling "holes" with the drill press. Basically, I would drill a "hole", rotate the gear, drill another "hole", etc until I went all the way around. I then put a 7/16-14 tap from a tap and die set on the drill press set on its lowest RPM setting and used it to cut the threads in the worm gear.
It seems to work fine, although I haven't checked it for accuracy.
I don't think that it would be too hard to do it with just a normal power drill if you don't have a drill press, but you would probably have to make some kind of jig to make it work.
I made a worm gear in the past that worked pretty well. It's at this link. http://www.cerebralmeltdown.com/cncstuff/page3/wormgear/default.htm
I will add that cutting the threads with a tap was much easier than the method used there.
That's what I have so far. More to come.