Author Topic: How do you adjust Davis single spoon upgrade  (Read 2591 times)

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Offline dasman

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How do you adjust Davis single spoon upgrade
« on: March 28, 2020, 04:50:09 PM »
I have the vantage pro 2 single spoon upgrade installed. It has gone through 8 or 9 rain events and consistently runs 8% low. I would like to make an adjustment but not sure how. has anyone adjusted these yet. Is it the single Phillips screw? Note.... I have the ISS perfectly level!
Dave Sommerfed
Peotone Illinois USA
CW7762, KILPEOT1
NWS COOP, CoCoRaHS, Spotter Network

Offline CW2274

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Re: How do you adjust Davis single spoon upgrade
« Reply #1 on: March 28, 2020, 05:01:24 PM »
I imagine it's similar with others, but with WeatherLink you can adjust it in the software by single percentages if you don't want to mess with the tipper itself.

Offline dasman

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Re: How do you adjust Davis single spoon upgrade
« Reply #2 on: March 28, 2020, 05:06:19 PM »
The old spoons had 2 bolts (1 under each bucket). This has a screw on the arm and now I see a hidden screw as well. I have thought about just using the software!
Dave Sommerfed
Peotone Illinois USA
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NWS COOP, CoCoRaHS, Spotter Network

Offline CW2274

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Re: How do you adjust Davis single spoon upgrade
« Reply #3 on: March 28, 2020, 05:17:41 PM »
I have thought about just using the software!
So have I, but as stupid as it sounds, it's like cheating to me so I do my calibrating on the bucket itself. However, I have a Rainwise, so I don't know how yours is adjusted. Can't be too hard to figure out. Got time on your hands?

Offline dasman

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Re: How do you adjust Davis single spoon upgrade
« Reply #4 on: March 28, 2020, 05:21:12 PM »
Yea I probably will just make a small adjustment on 1 screw and see if anything changes after the rain. Just wish i could find documentation.
Dave Sommerfed
Peotone Illinois USA
CW7762, KILPEOT1
NWS COOP, CoCoRaHS, Spotter Network

Offline CW2274

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Re: How do you adjust Davis single spoon upgrade
« Reply #5 on: March 28, 2020, 05:28:57 PM »
It's very simple and inexpensive to make your own calibrator, it's just very time consuming to calibrate properly.

Offline schwab

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Re: How do you adjust Davis single spoon upgrade
« Reply #6 on: March 29, 2020, 09:20:46 AM »
I also just replaced my two spoon rain gauge tipper with the Davis single spoon USA upgrade. 7345.425

I emailed Davis customer support today requesting re-calibration instructions of factory screw settings and I included a link to this thread on our forum.

Davis hopefully will fulfill the request and appreciate my feedback regarding the total absence of any installation instruction, any written manual & any written calibration instructions. 

Davis advertises as a serious weather instrument manufacturer...hopefully Davis will appreciate that their loyal customer base especially needs excellent documentation support accompany this 7345.425 product upgrade.


Offline optical_man

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Re: How do you adjust Davis single spoon upgrade
« Reply #7 on: March 29, 2020, 08:32:31 PM »
What a coincidence.  Today, I also noticed that the tipping spoon on my brand new ISS is reading 8% low.  Although, now I'm realizing that it is probably because I had an issue getting the entire ISS level when attached to a J-pole.  The pole was perfectly level before mounting the ISS, but the unbalanced weight made it tilt a bit.

The manual for the old bucket mentions an adjustment range of only about +/- 2%.  Since I need 8%, I should level the ISS better.

Offline SnowHiker

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Re: How do you adjust Davis single spoon upgrade
« Reply #8 on: March 30, 2020, 02:18:21 PM »
The manual for the old bucket mentions an adjustment range of only about +/- 2%.  Since I need 8%, I should level the ISS better.
Leveling is always a good idea, but if I'm not mistaken it's 2% per turn of the screw, so just make more turns to get 8%.  Although, as it's a brand new ISS, you may want to make sure it's consistently low over a few rain cycles before adjusting, or at least make small adjustments and try to keep track of how far you turn the screws.

Offline optical_man

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Re: How do you adjust Davis single spoon upgrade
« Reply #9 on: March 30, 2020, 03:59:32 PM »
Since my unit is difficult to reach, I'd like to hear from someone as to how far the adjustment allows before I start monkeying with it.  The graphic in the old user manual shows a quarter turn is 1.5%.  If it allows a full turn or more, then each turn would equal 6%.  But, can it turn that far?  Has anyone experience with that?
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Offline Mattk

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Re: How do you adjust Davis single spoon upgrade
« Reply #10 on: March 30, 2020, 07:09:00 PM »
Yes the old rain collector adjustment would go a lot more than a single (6%) turn. Adjustments of 20% or more was not uncommon. The trick is not to try and adjust large adjustments in one go as things can very quickly go the other way. If say you have a 12-15% adjustment then do 6%, 1 turn and then re-calibrate 

Offline havtrail

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Re: How do you adjust Davis single spoon upgrade
« Reply #11 on: March 30, 2020, 07:36:02 PM »
What a coincidence.  Today, I also noticed that the tipping spoon on my brand new ISS is reading 8% low.  Although, now I'm realizing that it is probably because I had an issue getting the entire ISS level when attached to a J-pole.  The pole was perfectly level before mounting the ISS, but the unbalanced weight made it tilt a bit.

The manual for the old bucket mentions an adjustment range of only about +/- 2%.  Since I need 8%, I should level the ISS better.

8% off compared to what? A more trusted rain gauge sited at the same location? Rain can be highly variable between locations.

Rich K.
Onset HOBO RX2102 Cellular
https://www.havtrail.com/weather/
NEWA https://newa.cornell.edu Haverford, PA

Offline johnd

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Re: How do you adjust Davis single spoon upgrade
« Reply #12 on: March 31, 2020, 04:06:32 AM »
Since my unit is difficult to reach, I'd like to hear from someone as to how far the adjustment allows before I start monkeying with it.

I'm confused! You report having the new tipping spoon mechanism but are referring to the old manual for the tipping buckets. The adjustment for the spoon is nothing like the old buckets and there is no read across of adjustment methods or amount.

I agree that step one is to be absolutely sure that any reference gauge you're using is a reasonably reliable one (eg a CoCoRaHS) and is located at the same place and with the mouth at the same height as the Davis gauge.
Prodata Weather Systems
Prodata's FAQ/support site for Davis stations
Includes many details on 6313 Weatherlink console.
UK Davis Premier Dealer - All Davis stations, accessories and spares
Cambridge UK

Sorry, but I don't usually have time to help with individual issues by email unless you are a Prodata customer. Please post your issue in the relevant forum section here & I will comment there if I have anything useful to add.

Offline eliteweathernz

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Re: How do you adjust Davis single spoon upgrade
« Reply #13 on: March 31, 2020, 09:51:23 PM »
I have a rain gauge calibrator made by Novalynx.

I am currently calibrating my 3 stations.

You must have a constant flow rate and also a precisely measured volume of water.

If you don’t have these then your calibrations are going to be off.

Also need to ensure your buckets tip evenly or again you’ll forever have under reporting.

With the single spoon this is removed as an issue. I believe there is a way to calibrate the single spoon but I have not myself yet attempted it. I have 2 gauges with twin spoons and 1 with the new single spoon.

Happy to answer questions.

Offline CW2274

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Re: How do you adjust Davis single spoon upgrade
« Reply #14 on: March 31, 2020, 10:14:21 PM »
You must have a constant flow rate
Completely false. Do you think Mother Nature has a "constant flow rate?" I made my own calibrator and it doesn't flow at a constant rate and I'd be willing to bet that I have my RainWise tipper calibrated better than when I got it from the factory. I take my time, and I'm a ridiculous perfectionist.

Offline eliteweathernz

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Re: How do you adjust Davis single spoon upgrade
« Reply #15 on: April 01, 2020, 02:00:01 AM »
Would be interesting to compare using an actual rain calibrator. Not one fabricated with an unknown flow rate and volume

My Davis rain gauges are calibrated to + or - 1% or 0.05mm.

I first ensure both sides of a twin spoon tip evenly ie same volume of water on each side per tip. This ensures you don’t have one side taking more or less to tip, that will throw a calibration straight away.

Secondly I measure a 450ml volume of water ie 450g=450ml of water into the measuring cylinder.
I then attach a precise orifice/hole to drip that water through the rain gauge. I expect 105 tips/450ml of water using the 1/32” orifice.
I run the test until I see a steady figure or a plus or minus 1 tip variance.
Then I know I’m in the right zone, if I need to adjust then I carefully adjust each set screw equally to not upset the balance.
I verify my balance again.

Then re test. This as you can see takes sometime but I have successfully got it tipping 104-105 times consistently. In terms of that I can’t ask for much better and anything outside that would be an environmental/ random error no one can account for.

The faster the drip rate the higher chance you have of splash out from the buckets hence error increases at higher rain rates.
So consider your typical annual rain rates when deciding what flow rate to use.


Offline CW2274

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Re: How do you adjust Davis single spoon upgrade
« Reply #16 on: April 01, 2020, 02:38:10 AM »
Secondly I measure a 450ml volume of water ie 450g=450ml of water into the measuring cylinder.
I expect 105 tips/450ml of water using the 1/32” orifice.
Unless the new Davis single spoon design is somehow different on measurement (which I have no idea if you're even using it), the VP2 uses 544ml for 1 inch of rain (100 tips).

Would be interesting to compare using an actual rain calibrator. Not one fabricated with an unknown flow rate and volume
If that comment was meant about my calibration, you have absolutely no idea what you're talking about.

Offline eliteweathernz

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Re: How do you adjust Davis single spoon upgrade
« Reply #17 on: April 01, 2020, 05:27:45 AM »
If you refer to photo attached.
Yes your right that 5.44cc/tip is correct for 0.01inch/tip
If you use 450cc of water then you should receive 83 tips.

I’m using metric measurement so 4.28ml of water is equal to 0.2ml/tip.
Hence I use 450cc of water and should get 105 tips.

That’s using a given flow rate of 24cc/minute. So it takes roughly 19 minutes
 to empty 450ml through the gauge.

That flow rate is equivalent to 79mm/hour or 3.11 inch/hour which is the most suitable to my location setting.

I use an automated tip counter also.

If you want more information on this I can send you a link.

I guess this is a little more scientific and I have given values to work from.

Not saying your method is wrong, guess what works for you is fine. I just trust my method a little more.

Offline CW2274

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Re: How do you adjust Davis single spoon upgrade
« Reply #18 on: April 01, 2020, 03:52:03 PM »
I just trust my method a little more.
You don't even know what my "method" is. Put it to you this way, any day you want to put your VP2 tipper up against my RW....I own both.

Offline Mattk

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Re: How do you adjust Davis single spoon upgrade
« Reply #19 on: April 01, 2020, 07:02:35 PM »
Would be interesting to compare using an actual rain calibrator. Not one fabricated with an unknown flow rate and volume

My Davis rain gauges are calibrated to + or - 1% or 0.05mm.

I first ensure both sides of a twin spoon tip evenly ie same volume of water on each side per tip. This ensures you don’t have one side taking more or less to tip, that will throw a calibration straight away.


Some comments in regard the above

- A tipping rain gauge will always have a variation due to varying flow rate as that is what rain consistently does, vary in intensity so using any sort of calibrator will only ever be valid (as such) for one particular rain rate and with rain that will never happen. This is one reason that critical tipping gauge models also collect the physical rain amount for manual comparisons as required. So it really doesn't matter if the calibrator is perfectly constant it will only ever provide a calibration at 1 and only 1 specific rain rate, which does not follow the real world.

- Claiming a gauge is calibrated to + or - 1% or 0.05mm along with rain rate variations is a little optimistic and especially for a tipper with a minimum resolution of 0.2mm, +/- 1% (0.05mm) is technically not feasible regardless of what numbers appear. The accuracy of a Davis tipping bucket gauge is around 5% 

- With tipping buckets it is really not ideal to really have each individual tip identical and due to the small volume involved is quite difficult to precisely achieve especially as it is not the volume of water that triggers the tip but the weight of water which can be quite variable in itself. The typical 2 tip total or groups of 2 tip totals average out any variation between each tipper so this spending a whole heap of time trying to balance each tip exactly is rather fruitless. In fact is best for the tipper to not be exactly identical which ensures a more exact tip without stuttering     
« Last Edit: April 01, 2020, 07:04:27 PM by Mattk »

Offline CW2274

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Re: How do you adjust Davis single spoon upgrade
« Reply #20 on: April 01, 2020, 07:44:08 PM »
That's why my calibrations takes so long, I vary the rate to see the various results. Last time I did my RW, I believe I was satisfied after three days of testing with the starting flow at about a 4.5" per hour and finishing at about 0.5" per hour.... and that's only after many "lather rinse repeat" cycles. Good to go. [tup]

Offline schwab

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Re: How do you adjust Davis single spoon upgrade
« Reply #21 on: April 02, 2020, 07:28:25 PM »
I appreciate the importance of a perfectly level rain collector to optimize accuracy of the the Davis single spoon USA tipper upgrade. 7345.425

Among those who have contributed to this thread and those interested in this thread...Please help build a stepwise method to adjust our single spoon tippers:

Some suggestions...

1. Exactly which screw needs to be turned?
2. In what direction should the screw be turned in order to increase/decrease the number of tips per volume of rain?
3. One complete turn of the screw will increase/decrease the rain collected by approximately what %?

BTW I have yet to receive a reply from Davis Instruments regarding the 72345.425 adjustment instructions.

Thank you for the time and attention of forum members willing to assist in this effort to build adjustment instructions.


Offline CW2274

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Re: How do you adjust Davis single spoon upgrade
« Reply #22 on: April 02, 2020, 07:46:19 PM »
I appreciate the importance of a perfectly level rain collector to optimize accuracy of the the Davis single spoon USA tipper upgrade. 7345.425

Among those who have contributed to this thread and those interested in this thread...Please help build a stepwise method to adjust our single spoon tippers:

Some suggestions...

1. Exactly which screw needs to be turned?
2. In what direction should the screw be turned in order to increase/decrease the number of tips per volume of rain?
3. One complete turn of the screw will increase/decrease the rain collected by approximately what %?

BTW I have yet to receive a reply from Davis Instruments regarding the 72345.425 adjustment instructions.

Thank you for the time and attention of forum members willing to assist in this effort to build adjustment instructions.
Firstly, by what manner makes you think it's out of calibration?

Offline schwab

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Re: How do you adjust Davis single spoon upgrade
« Reply #23 on: April 02, 2020, 07:53:38 PM »


In comparison to my nearby CoCoRHaS gauge...but this is a 'work in progress'...awaiting the next rain.
« Last Edit: April 02, 2020, 08:58:56 PM by schwab »

Offline tmabell

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Re: How do you adjust Davis single spoon upgrade
« Reply #24 on: April 02, 2020, 08:03:08 PM »
It's a good question.  It's immaterial as to why someone is asking.  A good answer will be archived here should anyone need that information in the future so I'm not sure why one needs to justify their request.