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Suggestions for another part of the heliostat is needed!

https://www.instructables.com/id/HELIOSTAT/
First of all thank you especially forgesmith for your help. Now is the time for the replacement for the rubber bands (to split the distance) in the plan. Any ideas? My twin spools that retract like a tape measure can work. Also 2 "geared" wires with a gearwheel in the middle would work. The centre of the reflector be joined to a piece that passes through the gearwheel.
(I will draw it later!) Anyways, hope to get some answers. Thank you Brian
The part of the question below has been answered!
Basically i have to attach the reflector so that it can swivel round the mounting.
The way old farm tractor 3 point linkages worked on the back would be perfect. The side arms have a little ball in them and you put a shaft on the attached plough or whatever through a hole in the ball and fasened it with a clip.
Imagine the reflector in place of the side arm and you have a perfect attachment BUT there is probably a modern urban alternative.
Can you think of one?
I am in no big rush myself because I have a big work project to complete but suggestions would be awesome for the near future.
Thank you
Brian White

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gaiatechnician (author) 8 years ago
I have a new idea for the heliostat. There is a limited type of heliostat that has a mirror rotating in 48 hours on equatorial mount. I do not have complete details yet. Apparently the mirror has to be "in the plane of the axis of the mount" . The mirror will reflect to the same place all day if those conditions are filled. I guess if the mirror is not in the plane, the reflection will still be "nearly" in the right place. So why not get this nearly right thing and apply a sun pointer to the back (on 24 hour rotation) and a stationary target pointer to the front to make the fine adjustments? I found with the gimbal that it has to make crazy swings on 2 axises at certain times in the rotation. This is very difficult. With the 24 hr rotation piggy backed on the 48 hr rotation, these contortions would be avoided! Anyway, let me know what you think. Brian
forgesmith8 years ago
Three point hitch.

[http://www.tractorsupply.com/webapp/wcs/stores/servlet/ProductDisplay_10551_10001_33790_______14345|14346|14347|14353|33790?listingPage=true Top link end.]

Functionally similar to a tie rod end, there's a ball retained in a housing, something is bolted to ball, allowing great range of movement relative to what the ball housing is attached to, often a rod. The difference is a tie rod end, in my experience, has a tapered stud with threads then the stud goes into a tapered hole, a link end has a ball with a thru hole that gets placed in a yoke with a cross pin holding it all together. However tie rod ends are not known for allowing the ball to rotate while a link end is made for rotation.

In industry that's called a ball joint rod end bearing, lots of sizes available, link goes to a supplier. This Wikipedia article shows it a little better. Here are yokes. Bearing and yoke together can form a clevis joint.

But in this application looks like a bolt is going thru the bearing hole, nut on each side would work good, then the reflector goes on the bolt.

Vehicle tie rod ends are stiff, they're assembled tight to better withstand all the pounding they'll get. But a new ball joint rod end bearing will be nice and loose.

Check out Lowes' hardware section or your local hardware store, if you want to see them first, otherwise the link provided is a good industrial supplier. I believe I've seen them used on the ends of turnbuckles with yokes as adjusters on equipment, and they just look handy, so the small ones might be more available than you'd think. Print out a picture of one to bring along for the clerk though, they may know it by a different name, and we're already up to a few.

Oh, I can think of a few functionally similar things, and the lathe work it'll take to make them, but no "urban alternative." And for the price, off-the-shelf is a good way to go.

And yeah, offhand it should work.
Nice research! Seems like you basically went up one mental directory from what I was thinking. All tie-rod-ends are ball joint rod-end bearings, but not necessarily the other way 'round. I guess I never knew because I never encountered them outside of cars. And I never had to look at that section in the hardware store...
Seems like you basically went up one mental directory from what I was thinking.
Or, I simply saw them before, knew of them, and the "research" was finding out what name to use for searching. Oh, and I'm guessing a hardware store would have them with other oddball bits, at Lowes where they have the pull-out bins for the less-common items I've found things I thought I'd have to order from an industrial supply company.
gaiatechnician (author)  forgesmith8 years ago
Thank you very much for your help. a ball joint rod end bearing would have been perfect but I did not find any! So I went with a gimbal. My first one is made from plywood so it might not last long. I am joining the target pointer to the end of the axle which is great! Saves complications. I have not yet put the sunpointer on. I hope to do that tomorrow. I have bought 2 metal rings so I hope to make 3 heliostats in total. The second 2 will be slightly concentrating because I want to use them to power a solar cooker. I plan to turn them all with dripper trackers. The dripper trackers are to be controlled by just one clock. Hope it works! Brian
Goodhart8 years ago
A universal joint would allow turning from several angles.
Universal_joint.png
gaiatechnician (author)  Goodhart8 years ago
That should work! and if there is a hole through the middle of the piece with the 4 spikes on it I could mount the "target aimer" in the middle. The "sun aimer" could be attached to an extension to one side of the piece that has a hole in it for the spike. The second part of the universal joint would be replaced by the reflector.
???

If you want to try a U-joint, you can find a basic one where they sell socket wrenches, that's a common attachment. But don't expect holes in the spider (universal industry name for round spikey things) unless they come with them, u-joints are used for high-torque applications thus the spiders are hardened.
gaiatechnician (author)  forgesmith8 years ago
I am going to try to make a gimbal. I had a look and it qualifys as a universal joint with a hole in the middle! (I think) Ideally i would have a metal ring as part of my gimbal but I could not find one. (A metal ring with 4 spikes in it.) Using a gimbal should allow me to put the target aimer in the middle on a fixed mount with the sun pointer and the gimbal mounted reflector rotating round it on equatorial mount . Thanks for putting me on the right track Brian
Hmm, gimbal, looks like a 2-axis gimbal set is needed. 3 to 4 rotating points. Ball joint, 1 rotating point. How much force is available for positioning, friction at those points could be an issue.

Ideally i would have a metal ring as part of my gimbal but I could not find one.
(A metal ring with 4 spikes in it.)
Saw off a thick slice of pipe, mark where 2 perpendicular centerlines hit the edge, drill 4 holes (drill press and vise for straightness), tap, apply bolts/screws, metal ring with spikes. For a "center hole" use long bolts/screws that go into a block with a hole centered in the ring. For mechanical reasons (thread alignment) one set of holes is drilled for clearance (bolt slides thru) while the other is tapped, best scheme is the center block is tapped while the ring is clearance, use a nut on each side of a ring hole to hold bolt in place.
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