Author Topic: Tipping spoon (new type) - adjusting  (Read 9025 times)

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Offline Mattk

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Re: Tipping spoon (new type) - adjusting
« Reply #25 on: October 30, 2021, 12:12:43 AM »
How much does one turn of the screw change measurement?
Say my single tipper guage is measuring 15% low compared to stratus manual Guage next to it, how many turns of screw is needed to calibrate?
Thanks
Frank

Totally trial and error as the adjustment is non-linear due to being relative to the magnetic effect as distance changes. This tipping spoon adjustment is totally different to the linear relationship of the 2 screw tipping buckets.

15% ?? I have not had a tipping spoon yet that is not within spec < 4%

Offline ocala

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Re: Tipping spoon (new type) - adjusting
« Reply #26 on: October 30, 2021, 06:57:21 AM »
I know that a lot of people are new to this hobby but the main thing to keep in mind when calibrating your station is it's a micro climate. Meaning your your back yard. Not some station miles away or even down the block. If you want to calibrate the tipping bucket get a manual gauge and mount it right next to it. Make sure it's a type of gauge that is approved by the weather service in your country for accuracy. Even then there could be differences because of the size of the openings in the gauges but it will be more accurate then a station farther away.
« Last Edit: October 30, 2021, 07:00:14 AM by ocala »
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Offline fkapp

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Re: Tipping spoon (new type) - adjusting
« Reply #27 on: October 30, 2021, 07:21:28 AM »
Thanks guys. Just setup the cocrahas manual Guage on fence nearby and is measuring more than the Davis past 2 significant rains.
Possibly tree shadow for Davis one but thought was far enough away as manual one is farther away. Will monitor for a few more rains then try screw adjustment.    Probably will end up with a 2nd Guage placed by the manual Guage and probably will go with the rainwise one.

Offline johnd

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Re: Tipping spoon (new type) - adjusting
« Reply #28 on: October 30, 2021, 07:40:41 AM »
You've got to get them close together and with the funnel openings at the same height to be able to draw any reasonable conclusions. It's potentially a pain I know but otherwise you just really cannot be sure of any comparisons and therefore about any changes you decide to make.
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Offline CW2274

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Re: Tipping spoon (new type) - adjusting
« Reply #29 on: October 30, 2021, 05:23:17 PM »
Granted better than nothing I guess, but personally, I think using one rain gauge to calibrate another is a fool's errand even if it's a Stratus. Calibrate the tipper with a known, accurate quantity of water. 

Offline Mapantz

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Re: Tipping spoon (new type) - adjusting
« Reply #30 on: February 19, 2022, 11:20:49 AM »
This is my third time trying the newer spoon tipper, and it is still over-reading compared to my two manual gauges and another automatic rain tipping gauge.

I did a huge load of upgrades to my station and thought I'd give the spoon tipper a try again. It's over-reading by about 1.5mm for every 5mm of rain. I've tested this over and over again, with the same results on all three spoon tippers I have tried.

The most amusing thing of all though, is that when they've gone back to the shop to be tested, I've been told that they are under-reading. That's complete nonsense! They may well be under-reading against Davis' own calibration system, but 100% not in my tests.

To be clear here, one manual gauge is right next to my Davis rain gauge - same height. The other is at ground level, and the other automatic tipper is at the same height as the Davis, but around 8 feet away.
I don't need to be told "You need to actually pour a certain amount of water in .. blah blah"
It's blatantly obvious that they are over-reading.
I swear on my fathers life that both manual gauges and the other rain tipper are always within 0.5mm of each other. The manual gauges are always practically identical!

Today has registered 6.4mm on the Davis. Both manual gauges have 5mm exactly, and the other automatic tipper has 5.1mm.

Another example; Last Sunday, 21.2mm on the Davis, the other gauges were around 16mm. This is exactly the same issue as I had on the other two spoon tippers that I sent back. There's something seriously wrong with the way they are being calibrated, no two ways about it!


Offline Mattk

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Re: Tipping spoon (new type) - adjusting
« Reply #31 on: February 19, 2022, 04:29:12 PM »
To have three (3) spoon tippers behave the same like you describe then you may need to look elsewhere other than a straight calibration issue? Every tipping spoon I have checked have been less than the stated 4% so for three to be the same 30% out does raise a question?

My first impression with those figures is an improper configuration between Imperial & metric spoon and/or configuration variables? For example 5mm of rain with a 0.2mm tipper is 25 tips, 25 tips @ 0.01" (0.254mm) is 6.4mm, which is way to much of a coincidence? 

Offline DaleReid

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Re: Tipping spoon (new type) - adjusting
« Reply #32 on: February 19, 2022, 04:33:46 PM »
Mapantz:
I know the feeling of frustration and while I won't detail it here, one summer when we DID have rain at regular intervals and varying amounts, a retired friend set up about a half dozen tippers, and five varying sized fixed rain gauges, including two of mine which were old national weather bureau and an expensive plastic COCORAHS type along with another that was just a straight tube.

These were all mounted on top of a flat roof with their tops about as close as possible to the same height, not too near the edges so wind effect was minimized, and the roof was level on one end with a earth berm so we could walk out onto the roof and take very careful reading (from the manual ones) and dump them, check for bugs and insects, etc.

Only a few times did he ever see a rain storm register close (within a few 0.01" of each other, with the straight tube, non-multiplying manual gauge being very hard to read to any degree of accuracy being the most difficult to judge small amounts of rainfall.

Rarely did the tippers agree precisely.  0.05" was a happy day.

We did the exact calculations for the size of the collection throats, with very careful micrometer measuring to make sure we got the numbers right, and calculated the weight of the water to put in.  Obviously the manuals we could just pour it in.  The tippers needed to have a slow enough rate that they wouldn't drip while tipping and under report the amount of rain, which was an enormous pain and time consuming especially having done them at least three times.  Those calibration checks DID show up the same or within a 0.01" per 1/2" or full inch, so we KNEW that under best conditions, they WERE measuring correctly.

The end result is that why not just bite the bullet, calculate or see what the manual says for the amount of water to use, the rate to use and weigh the grams out and do a test an afternoon or two.  I used an old IV tubing with a little knob that adjusted the drip rate so it was a controlled rate, but not everyone might have access to that.  And the commercial drippers are obscenely expensive for a piece of plastic.  The rate doesn't have to be constant, so a small plastic cup with a small hole in it will drip through over a period of time, just don't run it very fast.

Why did he and I do this?  Because we were bound and determined to have exceptionally precise measurements of the rain.  Now I know better.  The best example  of local variation as Ocala points out can be quite different even across a few feet, was when one of the rainstorms had one of the tippers show almost 1/2" MORE than all the others.  There had been a period of heavy rain, and wind, so I surmised that those sheets of rain you see falling might have swept across the one gauge, causing more to fill than those gauges even next to it.  I've seen it raining heavy on one side of my house and look out the opposite side where literally there wasn't any falling, at least yet.  So there are even micro-micro variations.

DO THE DRIP TEST, then you'll know how accurate your spoon tipper is and if you need to just trash it and wire in an old fashioned teeter totter type. 

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Offline DaleReid

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Re: Tipping spoon (new type) - adjusting
« Reply #33 on: February 19, 2022, 04:38:59 PM »
Mattk:  You raise an interesting question.  Do the manufacturers of tippers make different sized spoons/buckets for inches vs. mm of rain, or just fiddle with the screws so they tip at the correct amount?

I know I two replacement mechanisms for a commercial rain gauge with a throat of about 12" (!) and one of them says mm of rain and the other says inches of rain on the label on the inside.

Just curious.  When I set the two tippers up next to each other, visual inspection shows an obvious size difference in them, so that manufacturer at least seems to have engineered and manufactured two sizes.

Just curious what the advanced amateur stuff like Davis et. al do?

Surprisingly the siphon type from RM Young, which I spent far too many hours fiddling with a couple years ago, was within a few points at 50 mm of rain over and over.  Hard to believe when you look inside to see how they work.
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Offline CW2274

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Re: Tipping spoon (new type) - adjusting
« Reply #34 on: February 19, 2022, 04:51:43 PM »
I used an old IV tubing with a little knob that adjusted the drip rate so it was a controlled rate, but not everyone might have access to that.  And the commercial drippers are obscenely expensive for a piece of plastic.
For sure. When I saw what NovaLynx wanted for a calibrator (like $140 IIRC), I said screw that and built my calibrator of of a gallon milk jug and rope putty to vary the flow hole. Works like charm.

Offline Mattk

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Re: Tipping spoon (new type) - adjusting
« Reply #35 on: February 19, 2022, 05:23:21 PM »
Mattk:  You raise an interesting question.  Do the manufacturers of tippers make different sized spoons/buckets for inches vs. mm of rain, or just fiddle with the screws so they tip at the correct amount? ....

The original Davis Tipper had unique replaceable magnetic counter weights that changed the sea-saw tipper from imperial to metric, the buckets remained unchanged. Unsure re the exact mechanism of the tipping spoon but one would expect it is relative to weight hence the counter weight/magnet is "probably" the controlling factor? 

Offline davidmc36

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Re: Tipping spoon (new type) - adjusting
« Reply #36 on: February 19, 2022, 07:30:44 PM »
That's the only difference in the Metric and Imperial that I can see. The plastic magnet holder for metric is larger. Very small weight difference.

Offline Mapantz

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Re: Tipping spoon (new type) - adjusting
« Reply #37 on: August 24, 2022, 09:54:48 AM »
I want to bring this back to the forefront again, as this is becoming a bigger issue than people think.

I have been discussing this spoon tipper with a few other people on another forum, they are all suffering the same issue.. the spoon tipper overreads by quite a margin. Of three that I have tried, they all do it. I've reported it to the seller each time, and all I get is "we'll contact Davis" and then you never hear anything again.

I've contacted Davis on numerous occasions, and guess what? They never reply.


Offline Sylver19

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Re: Tipping spoon (new type) - adjusting
« Reply #38 on: September 18, 2022, 01:03:23 AM »
Bonjour , en France toutes les vp2 que j'installe avec la cuillère sont étalonnées , il faut 4 ml d'eau pour obtenir un bon basculement pour avoir 0.2 mm  de pluie et cela reste stable meme avec le réchauffeur de cone .
« Last Edit: November 05, 2022, 04:57:08 AM by Sylver19 »

Offline TMThomson

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Re: Tipping spoon (new type) - adjusting
« Reply #39 on: October 27, 2022, 01:17:21 PM »
To have three (3) spoon tippers behave the same like you describe then you may need to look elsewhere other than a straight calibration issue? Every tipping spoon I have checked have been less than the stated 4% so for three to be the same 30% out does raise a question?

My first impression with those figures is an improper configuration between Imperial & metric spoon and/or configuration variables? For example 5mm of rain with a 0.2mm tipper is 25 tips, 25 tips @ 0.01" (0.254mm) is 6.4mm, which is way to much of a coincidence?

Mattk,

I’ve had two tipping spoons. The first (which came which came with my new VP2) read 30% low. The replacement Davis sent reads 35% high. From -30% to +35% is quite an accuracy spread - definitely a calibration issue with these new spoons. It’s not the ISS, the console or any settings. I'm using a standard CoCoRaHS gauge at the same height and within 2 feet of the VP2 for comparison. Davis Tech Support has been of little assistance to top it off.

Offline TMThomson

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Re: Tipping spoon (new type) - adjusting
« Reply #40 on: November 04, 2022, 06:24:32 PM »
I want to bring this back to the forefront again, as this is becoming a bigger issue than people think.

I have been discussing this spoon tipper with a few other people on another forum, they are all suffering the same issue.. the spoon tipper overreads by quite a margin. Of three that I have tried, they all do it. I've reported it to the seller each time, and all I get is "we'll contact Davis" and then you never hear anything again.

I've contacted Davis on numerous occasions, and guess what? They never reply.


Mapantz,

I just had a rainfall of 0.65" measured by a CoCoRaHS gauge. The Davis read 0.93"!!! Over 40% too high. I'm going to try the manual adjustment to the tipping spoon.

I really wish Davis Instruments had the integrity to admit that they have a quality control problem on their hands and it's damaging their reputation. This has been super frustrating!

Offline CW2274

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Re: Tipping spoon (new type) - adjusting
« Reply #41 on: November 04, 2022, 07:18:17 PM »
I want to bring this back to the forefront again, as this is becoming a bigger issue than people think.

I have been discussing this spoon tipper with a few other people on another forum, they are all suffering the same issue.. the spoon tipper overreads by quite a margin. Of three that I have tried, they all do it. I've reported it to the seller each time, and all I get is "we'll contact Davis" and then you never hear anything again.

I've contacted Davis on numerous occasions, and guess what? They never reply.


Mapantz,

I just had a rainfall of 0.65" measured by a CoCoRaHS gauge. The Davis read 0.93"!!! Over 40% too high. I'm going to try the manual adjustment to the tipping spoon.

I really wish Davis Instruments had the integrity to admit that they have a quality control problem on their hands and it's damaging their reputation. This has been super frustrating!
Davis's rain gauge has always been a weak point. Several of us here use this. It's hands down a superior tipper on paper, and in actual use. It can be hardwired to the ISS just like the stock tipper and behaves the same.

https://rainwise.com/wired-rain-gauge

Offline Mattk

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Re: Tipping spoon (new type) - adjusting
« Reply #42 on: November 04, 2022, 11:03:44 PM »
I want to bring this back to the forefront again, as this is becoming a bigger issue than people think.

I have been discussing this spoon tipper with a few other people on another forum, they are all suffering the same issue.. the spoon tipper overreads by quite a margin. Of three that I have tried, they all do it. I've reported it to the seller each time, and all I get is "we'll contact Davis" and then you never hear anything again.

I've contacted Davis on numerous occasions, and guess what? They never reply.


Mapantz,

I just had a rainfall of 0.65" measured by a CoCoRaHS gauge. The Davis read 0.93"!!! Over 40% too high. I'm going to try the manual adjustment to the tipping spoon.

I really wish Davis Instruments had the integrity to admit that they have a quality control problem on their hands and it's damaging their reputation. This has been super frustrating!

I would be totally eliminating and then checking again for other issues. The last version tipping bucket was known for measuring under and by quite a bit but never ever saw one read over. The VP2 tipping spoon, have not come up with one yet that is outside 4%.

Would be looking for other issues before touching the spoon adjustment, one needs to be very satisfied before trying to adjust the spoon mechanism. I would be doing a calibration on the tipping spoon itself, fixed amount of water over time and actually counting/logging the number of tips and comparing that to the amount of water and size of cone, totally remove any console/software affect. What I use to simply count the raw tips with is an old Weather Monitor II   

Offline TMThomson

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Re: Tipping spoon (new type) - adjusting
« Reply #43 on: November 05, 2022, 03:57:11 PM »
Mattk,

I have checked everything I know of - including everything Davis Tech Support recommended. The tipping spoon that came with the VP2 in July was off minus 30%. Davis sent a replacement which was off plus 43%. At Davis Tech Support's suggestion, I made an adjustment and I'm now getting closer to spec as of todays rainfall.

I've noticed that you posted in a couple of places here insisting that you've never seen one outside of 4% - actually the spec on the new spoons is +/-3% or one tip - Well I have and so have many others. I'll be direct - it sounds like you're carrying water (no pun intended :grin:) for Davis. That's not helpful.  ](*,)

Offline kobuki

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Re: Tipping spoon (new type) - adjusting
« Reply #44 on: November 05, 2022, 04:03:51 PM »
I've purchased a tipping spoon to replace my old tipping bucket style sensor about a year ago. I postponed installing it so see if the issues brought up here and at other places are getting fixed or not. Apparently, Davis still gives a f*ck about factory calibration or making it simpler to adjust newer pieces. That's just too sad. I'm forced to use an external device for calibration if I ever plan to install my sensor. Add to all these the fiasco with the newer Sensirion sensors discussed in other threads, and this looks grim for Davis and their legendary reliability.

Offline WheatonRon

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Re: Tipping spoon (new type) - adjusting
« Reply #45 on: November 05, 2022, 04:07:52 PM »
Per Davis support, the tipping spoon cannot be calibrated unlike the old tipper (teeter-totter concept) Davis used before. I have downgraded my spoon tipper to the old tipper. I find it more reliable. The spoon tipper consistently over reports rainfall.
« Last Edit: November 05, 2022, 04:17:22 PM by WheatonRon »
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Offline Mattk

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Re: Tipping spoon (new type) - adjusting
« Reply #46 on: November 05, 2022, 05:33:01 PM »
Mattk,

I have checked everything I know of - including everything Davis Tech Support recommended. The tipping spoon that came with the VP2 in July was off minus 30%. Davis sent a replacement which was off plus 43%. At Davis Tech Support's suggestion, I made an adjustment and I'm now getting closer to spec as of todays rainfall.

I've noticed that you posted in a couple of places here insisting that you've never seen one outside of 4% - actually the spec on the new spoons is +/-3% or one tip - Well I have and so have many others. I'll be direct - it sounds like you're carrying water (no pun intended :grin:) for Davis. That's not helpful.  ](*,)

The question remains, have you actually checked the calibration?  If not then one actually does not know what is off and what is not.

What you might note is I am carrying an understanding of the this and suggesting a direction from a more experienced helpful direction, until you actually check the calibration of that gauge then adjusting it is based on the unknown.       

Offline WheatonRon

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Re: Tipping spoon (new type) - adjusting
« Reply #47 on: November 05, 2022, 06:03:46 PM »
Mattk,

I have checked everything I know of - including everything Davis Tech Support recommended. The tipping spoon that came with the VP2 in July was off minus 30%. Davis sent a replacement which was off plus 43%. At Davis Tech Support's suggestion, I made an adjustment and I'm now getting closer to spec as of todays rainfall.

I've noticed that you posted in a couple of places here insisting that you've never seen one outside of 4% - actually the spec on the new spoons is +/-3% or one tip - Well I have and so have many others. I'll be direct - it sounds like you're carrying water (no pun intended :grin:) for Davis. That's not helpful.  ](*,)

If I understand your statement correctly, Davis support had you calibrate a VP2 spoon tipper? They told me that calibrating the spoon tipper can’t be done (by us amateurs) since the measurements are “not linear.”
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Offline kobuki

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Re: Tipping spoon (new type) - adjusting
« Reply #48 on: November 05, 2022, 06:04:56 PM »
Per Davis support, the tipping spoon cannot be calibrated unlike the old tipper
But per users in this forum, it can be calibrated. That discrepancy alone is a fail on Davis' part.

Offline Mattk

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Re: Tipping spoon (new type) - adjusting
« Reply #49 on: November 05, 2022, 06:14:22 PM »
Mattk,

I have checked everything I know of - including everything Davis Tech Support recommended. The tipping spoon that came with the VP2 in July was off minus 30%. Davis sent a replacement which was off plus 43%. At Davis Tech Support's suggestion, I made an adjustment and I'm now getting closer to spec as of todays rainfall.

I've noticed that you posted in a couple of places here insisting that you've never seen one outside of 4% - actually the spec on the new spoons is +/-3% or one tip - Well I have and so have many others. I'll be direct - it sounds like you're carrying water (no pun intended :grin:) for Davis. That's not helpful.  ](*,)

If I understand your statement correctly, Davis support had you calibrate a VP2 spoon tipper? They told me that calibrating the spoon tipper can’t be done (by us amateurs) since the measurements are “not linear.”

No, Davis support did not have me calibrate a VP2 spoon tipper, I check the "calbration" (as such) of every gauge before installed be it spoon, tipper or whatever. Unless one checks the calibration (as such) then one can not guatantee the output, very simple quality assurance principles.  And yes you are correct in regard the non linear adjustment of the tipping spoon. 

Checking for any discrepancy provides some direction of what to next based on the calibration check.   
« Last Edit: November 05, 2022, 06:16:16 PM by Mattk »