Gina
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Everything posted by Gina
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S'alright tis on...
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on now.
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They have rounded front edges. (Can't play your video because the sound isn't working on my computer ATM).
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Oops - you beat me to it.
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Tonight 9pm BBC 2 - Horizon is about Pluto - Back from the Dead. From Radio Times :-
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For the wind vane where slow and back & forth motion is involved I'm going for PLA sideways bearings and a point contact single ball on a hard surface. The ball is a 14mm chrome steel bearing ball and the hard surface is a Neodymium Magnet (these are coated with a very hard material). Lubrication will be Liqui Moly 3510 LM 47 Long-Life Grease + MoS2 100 g This is the basic arrangement. Still developing the wind vane sensor and bearing unit but this is getting near. 8 reed switches held in holes. The weather hood will have a magnet to operate the switches.
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Bearings decided. I'm going for an SS ball bearing for the anemometer. S605ZZ EZO Stainless Steel Miniature Bearing 5x14x5 Shielded
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That's cheating!! Though I have used a similar technique myself! 😁 A craft type hot air gun comes in handy.
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Yes, as I understand it making your own actually costs a fair bit more than buying ready made. OTOH I have never got round to building my own (only looked into it a bit). There are several members who build their own and they will be able to tell you the costs.
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Don't know...
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I don't like printing very small stuff either. I shall have to finish my "GinaRep UltiPrinter" to print really small stuff. Might get round to it soon...
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Brilliant!!
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Ah!! That would explain it - thanks Wim 😀 I've printed the hub and Rrc comes out at 110mm giving Ar of nearly 2.3. This is a new (bigger) anemometer, previous one had Rrc of 75mm so 3 magnets for mph was about right.
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With the bottom end of Force 1 on the Beaufort Scale being 0.5 m/s it may make sense to use 4 magnets when counting pulses per second. With three magnets they fitted comfortable between the spokes but two or four don't so I may increase the hub size to accommodate the magnets. This would bring the Ar value up to 2. OTOH the tolerances we're discussing here are far less significant than things that interfere with the wind speed.
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Another bit says So maybe the formula near the end had a misprint! In my case the above would give about 1.9. So two magnets on the anemometer would give roughly metres/sec. Depends whether I want m/s or mph.
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Hmm... A is in metres/sec per Hz so presumably Ar is too. My Rrc is about 90mm, giving Ar = 1800. That doesn't make any sense!! I would expect a value around 1.
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I've found With Rrc in mm but not found what Ar is in.
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PHEW - Ma bwain 'urts Bwian!!! Just been "reading" the PDF. I shall need to try to read this again to get the calibration factor for my anemometer. One thing stood out though - the size of cup made little difference but the radius of cup centre from axle did. Intuition (or common sense) tells me that bigger buckets/cups should be better at overcoming friction in the bearing. I wonder if anyone has read this article and boiled it down to basics. How bucket centre radius relates to calibration. May go and have a lie down!
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Ah, so the value of 3 that I assumed wasn't that far off, but the PDF may give a better value. I shall be reading it. Thanks James.
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Found the post but it doesn't say how I got the calibration info.
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I seem to remember that somehow I estimated that a third of a revolution per second represented 1mph but I'll need to go through my Arduino weather station thread to see if I can find it.
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Well done
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Generally it's called "Sod's Law". And I agree entirely!! Yes, I'll put it where I can take it down for servicing fairly easily.
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Actually that bearing ball is 14mm not 12mm. I see I should also have 9.5mm bearing balls from searching my Amazon purchases.
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Hmm... Two opposing answers about ball size and grease or oil. If the cavity is filled with grease or oil a SS ball would not be necessary. I would worry about grease getting stiff when we get frosts. Another point - if filling the cavity with a light oil I could use a standard 5x10x4mm standard ball bearing I already have though a single bearing ball resting the the hex hole in the bolt head has appeal. That means the ball turns with the bolt and the ball to flat plate forms the end bearing. @ChriskeI'll draw a model with the 12mm (or 1/2" ball I already have).
