Anemometer

Hello,

As I'm about to mount my sun blinds¹, I need an anemometer to protect them from wind (they will be automatically raised when the wind reaches a pre-defined speed).

And I was wondering if I could not build my own wind sensor, as a classic anemometer...

Does anyone as already done somthing in this way?

I don't know yet if I will do it entirely printed, or if I make a mix of printed parts and laser cutted ones...

¹ [www.warema.com]

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Frédéric

First thing coming to my mind, printed plastic parts outside may not last very long. It would be a good idea to avoid direct sun or rain exposition.
I have a feeling that ABS would hold longer than PLA, but have no experience in that matter.

The same problem will occur with lasercut wood, you'd better choose some marine-rated material (and I don't remember if we can lasercut that, due to the potential Cl chemicals impregnated in those woods ?).

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Most of my technical comments should be correct, but is THIS one ?
Anyway, as a rule of thumb, always double check what people write.

Another stupid idea : wouldn't it be possible to measure something (current, tension) from a simple PC fan to measure the speed it is being rotated, and calculate wind speed from that ?

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Most of my technical comments should be correct, but is THIS one ?
Anyway, as a rule of thumb, always double check what people write.

I agree - exposure to the elements might significantly limit any printed parts life expectancy. ABS is probably the way to go if you had to.

You could use a PC fan, but then you need a vane to point into the wind. Problem is measuring light winds - the internal resistance of the fan would prevent it from picking up those small puffs of air. Anemometers are nearly friction-less (depending on construction) so they can catch the lightest breezes.

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- akhlut

Just remember - Iterate, Iterate, Iterate!

[myhomelessmind.blogspot.com]

I mainly use ABS for printing, so it should be OK, and even if I have to re-print some parts in 5 years, this is not a problem.

I made a first prototype using MDF to maintain the cups, but I will use PMMA for final part.

I will assemble the cups this week-end. Then, I have to design the body, and print it. Don't know what siez of bearing to use: I have very small ones (3 and 4mm for shaft); I think small bearing will have les friction...

Last, I have to make the detection part: I read that optical system should be avoided, and magnetic systems are better. Then, there are 2 solutions: use a hall effect sensor to detect a pusle, or use small coil, to get a voltage, which will depend on speed (several coils can be used).

As I said, by goal is to detect fast winds, and I mainly need 1 or 2 pre-defined thresholds to prevent the destruction of the sun blinds. The wind ensor as to be used in a KNX domotic system, where I have some unused digital inputs. So, the coils are maybe the way to go: I just need some OP AMP to detect a level, and close a contact. In the same time, it is also possible to detect the frequency, and make another electronic to measure the speed, and send it to some supervisor or so. But the threshold has to be very reliable, so I prefer a very simple solution, with few components.

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Frédéric

akhlut Wrote:
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> I agree - exposure to the elements might
> significantly limit any printed parts life
> expectancy. ABS is probably the way to go if you
> had to.

ABS is not weather-resistant (UV is the main problem). There is a ABS-like plastic called ASA which is specifically developed for outdoor applications.

Otherwise the design itself should be fairly easy to print. The conical cups with arms can be printed each in one piece and then attached to the rotating shaft. One problem is weather-sealing the bearings, since the usual sealed bearings are only dustproof. Rotating waterproof sealing is not a trivial matter...

You could use a small ball bearing encoder, like the ones from USDigital, and make the hub for the cups come down over it to protect it from the rain.

@Dad911: mmm, interresting! But they are not cheap ($70)...

@ttsalo: any idea where I can find some ASA? And what about painting the ABS?

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Frédéric

Orbi-tech.de is the only place I have seen ASA filament for sale and even they have only 4mm filament. I know it's possible to paint or otherwise weather-seal ABS too, but I don't know the details.

Polycarbonate (also available from Orbi-tech, at 3mm diameter) would be another option. That should be an extremely durable material. But you need a hotend that goes to 300C or so.

Edited 1 time(s). Last edit at 06/13/2012 08:22PM by ttsalo.

Thanks!

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Frédéric

Ok, I finally released a version which is close to the final one:

[www.thingiverse.com]

I'm waiting for the magnets to test and calibrate it.

Any feedback welcome.

Edited 1 time(s). Last edit at 08/06/2012 10:26AM by fma.

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Frédéric

If I printed this I would use some Marine grade varnish and spray a coat over it to give it some UV protection.

Good idea. I was planning to use simple paint for models, but a varnish is better.

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Frédéric

Yeah, Varnish being Marine grade will help with the UV protection and give it a smoother surface too (fills in the pits) plus it protects against rain damage (plastic is rain proof in of itself but most rain these days have slight amount of acid in them to what they call Acid Rain).

Thanks for these advices!

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Frédéric

Hi?I would really love to construct a simple anemometer,preferably homemade. Please send me a list of the materials needed and the procedure. I would really appreciate it.

@wendy, I didn't write any build procedure yet, as I didn't a complete one myself!

I hope to do that soon, but I have a lot of things to do at the same time!

I will post here as soon as I have news.

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Frédéric