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Heliostat Projects / Re: Worm thoughts
« Last post by Paul L on April 23, 2017, 07:58:57 AM »
Just a quick update on this idea:  It works really well as far as moving power is concerned.  I hooked up a 5v 28byj-48 to a common tuning peg, and attached it all to a lazy susan bearing which would act as the azimuth.  I stacked a three foot tall pile of textbooks on it, and it had no problem moving the whole thing, which was really amazing to me seeing how the running voltage was 5v, and roughly 200mA if I remember correctly (I did this a few months after the original post, so it's been awhile).  I'm guessing the books weighed thirty lbs.  It's slow but it works, and the resolution was pretty darn good!  The only drawback is the play when the motor stops - it's really sloppy.  There would have to be some kind of resistance to pull against the heliostat to tighten everything up.

I did take pictures with all the pieces I used, but I can't seem to find them now....I'll post them if I come across them.

This would most likely be the cheapest way to build a heliostat  - I think the motors, couplings, and tuning pegs came to less than ten dollars - per heliostat!  And it's not just a toy, it can move practical amounts of weight, including, I would guess, full sized mylar mirrors (4'x8').     
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Heliostat Projects / Re: Super low-cost heliostat with ESP8266 for WiFi control
« Last post by Gabriel on April 15, 2017, 10:28:27 AM »
This is a bit of a delayed reply, but you shouldn't need anti-backlash nuts. What would be more helpful is more of a say anti-backlash heliostat. So, the altitude and azimuth motions would be pulled in one direction by say a spring or a weight. That would help eliminate any wobble.

Also, It's something that I don't think I have documented well, but the closer you can keep the mirrors towards the axis of rotation the better. There will always be some drift as they get further and further  away, which may or may not be the reason for Paul's drift.

It's technically something that could be compensated for in the software, but it would add yet one more variable to the settings as I believe that you also need to have the distance to the target programmed in. I haven't gotten around to figuring out the math to compensate for it either.

I don't think it would take much to run a heliostat, or heliostats, off of solar. In the grand scheme of things they don't use much power. All they do is move part of a revolution forward and backward in each axis once a day, which amounts to practically nothing for smallish machines.

I actually managed to pick up a solar kit which even has the outdoor box for the batteries and charge controller for $10 dollars where I work, so I am planning on doing pretty much the same thing. Whenever I finally finish 3D printing all of the parts for it. Only 40 more hours of printing to go. ;)

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Thanks for all that info Paul - very helpful!  :)

Do you think I'd need an anti-backlash nut on my lead screws? They seem popular on CNC cutters/3D printers, but perhaps that precision isn't needed in this application?

I love your idea of using glued nuts for pivots! Simple and very economical.

I'm sharing all my code with Gabriel as I go along, and I'm hoping that at some point we'll have a single source tree that automatically recognises its hardware, and compiles the correct code for the Uno/Mega/ESP8266.

The EasyDriver board does indeed have its own regulator which can output 3.3V/5V, but apparently it can't manage a high enough current to drive the ESP8266 when it is using WiFi. I also want to completely disable the EasyDriver boards unless I need the motors to move, so for those reasons it makes sense to have the separate MP1584 powering all the logic.

I don't know how practical it will be to run the heliostats off (solar-fed) batteries, but I'm trying to minimise the power requirements so I can hopefully try that in the future.

Cheers
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Heliostat Projects / Re: Stepper motor rotary to linear motion.. HOW?
« Last post by Paul L on April 04, 2017, 04:20:22 PM »
You're right emimina, the newer versions are using worm gears.

They are definitely the better way to go (easier to set up, better range or motion).  But of course, they cost more.

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Heliostat Projects / Re: simple linear actuator instead ??
« Last post by Paul L on April 04, 2017, 04:15:55 PM »
Hi Emimina,

   The Sunharvester code has written is specifically for stepper motors - so the short answer is no, you can't use a linear actuator.  I think you may be able to do it, but it would require a bunch of re-coding adding some kind of optical encoder to the motor itself.  Hope that helps...
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Heliostat Projects / Re: Super low-cost heliostat with ESP8266 for WiFi control
« Last post by Paul L on April 04, 2017, 06:48:20 AM »
Hi Sheffieldnick,

  I would say yes, a counterweight would be a great idea; 10kg is pretty heavy for NEMA17, so if it's not balanced properly, they might have a tough go.  You shouldn't have to worry about wind movement when the steppers are off - the leadscrews are essentially self locking.  I used casters with the wheel taken off for the "screw nuts".  I took pictures and posted them in the forums here: http://cerebralmeltdown.com/forum/index.php?topic=305.msg1583#msg1583

For this design to work properly, you have to have everything plumb and level, with super accurate measurements and as little play in the parts as possible.  If any of those things are off slightly, you'll notice in the end, so take your time and do it right the first time!  Even my best build had a little bit of drift, and I tried damn hard to be accurate.  This is one of the reasons why I think worm gearboxes are the way to go - way less room for user/build error.  But if you're trying to keep costs to a minimum, this is the way to go!

Very cool that you'll be using the ESP8266 and the added features you've added in - it'd be great if you posted your code once you have it all up an running.  Also, ff I recall correctly, the Easy Driver has a 3.3v/5v linear regulator on board for external power supply, so you'd be able to use that to power the ESP8266 rather than the MP1584. 

Best of luck, and keep us posted!
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Heliostat Projects / Super low-cost heliostat with ESP8266 for WiFi control
« Last post by sheffieldnick on March 26, 2017, 03:08:45 AM »
I don't know if this forum is still active, but I'm starting on my own heliostat project and I'd really appreciate any advice that you experienced builders can offer  :)

Video of my prototype mechanical design, based on Gabriel's v2.0 design with lead screws. I don't need a wide range of motion, and I want to try something simple to maximise my chances of getting it working!
https://www.youtube.com/watch?v=fXRA-wfXz5A&feature=youtu.be

Each mirror is roughly 1000x750mm. Simple heliostat using a 5-10kg mirror made from 18mm plywood, CNC-milled into a shallow parabolic curve, reinforcing box metal strips (scrap) on the rear, and mylar film (emergency blanket) PVA glued on the front.

The mount is a 100x100mm timber post, rotating on a 12mm threaded rod through the center. I don't think I need a low-friction bearing, but rather something with the 'right' amount of friction that can be overcome by the stepper motors, while remaining still in the wind when the stepper motors are powered off? I was thinking perhaps drill+glue 100mm of a 200mm threaded rod into the bottom timber post, then run the rod all the way through the top timber post, securing it with a recessed nut at the top, but enough slack to allow the 0..45deg rotation?

Elevation and Azimuth motion provided by 2x NEMA17 stepper motors (purple), with physical limit stops and 4x electronic limit switches (red). The required range of motion is -15deg to +45 deg elevation, and 0 to +45 deg azimuth. I'm planning on using door hinges. Not sure how to attach the screw nuts (purple) so they can pivot freely?

Do I want a counterweight on the other side of the mount, to balance the 5-10kg weight of the mirror?

Controlled by an ESP8266 inside a waterproof case at the rear of the mount, along with 2x EasyDriver motor driver boards and a MPS1584 DC 12V -> +3.3V step-down voltage converter. I've ported Gabriel's Sun Harvester Program to the ESP8266, and added things like deep sleep mode for extra power saving, and fetching time/date with NTP rather than needing a physical real-time clock.

Total cost should be under 50.
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Heliostat Projects / Re: mechanics, a-frame on lazy-suzan
« Last post by emimina on February 27, 2017, 01:56:23 PM »
Did the idea work?
looks like the simplest design so far, however i am concerned on how will the mirror stand still in wind knowing that step motors are loose when its off
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Heliostat Projects / simple linear actuator instead ??
« Last post by emimina on February 26, 2017, 08:59:47 PM »
Hello
i was wondering if i can use simple linear actuator for use instead of the stepper motors with the control board sold on the website..
something like this https://www.youtube.com/watch?v=OhKsfWUM5nU

with the flexible hinges at the end, the attachment would be easier to the frame..
i am not sure who can help on this but i believe it will make the project easier to implement.

Thanks in advance
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Heliostat Projects / Stepper motor rotary to linear motion.. HOW?
« Last post by emimina on February 26, 2017, 01:11:24 PM »
Hi folks
i have been wanting to do this heliostat since a while, even found couple of providers for it (all under manufacturing now) but nothing beats the DIY prices..
in general i have an understanding now on the challanges on the current heliostat, and i have an idea for the design, however i failed to understand how the motors sold on the website store will turn circular motion to linear for the frame to move.
i understand on the older videos that gabriel used actuator with threaded rod as the shaft, so that if the motor moves, it actualy rotate the threaded rod , however the ones i see now on the website have regular shaft..
Does that mean that the new design only relies on the gears to transfer the shaft motion to frame circular motion? or am i getting something wrong?

Also did anyone try to implement the project all from the components on the store? if yes? what was the physical diagram for the heliostat?
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