Calibrating the Rainfall on a Davis Weather Station

Lukas Hanson
12 steps
24 seconds

If the rainfall on your Davis weather station seems to differ from actual rainfall, you can calibrate the tipping spoon to improve the accuracy of the readings The calibration procedure involves running a set amount of water through the rain bucket and counting the tips of the tipping spoon. If the number is higher or lower than 10 tips (which equals 0.1" of rain), you'll adjust a set screw to change the angle that the tipping spoon rests at.

Tools needed to calibrate the weather station: - Measuring cup or graduated cylinder to measure 55ml of water - Philips screwdriver - 1/4" socket - Water (a gallon should be more than enough) My recommendation for the screwdriver and socket is to use a screwdriver with a removable bit on the end. Most likely, the hole that the bit fits into is 1/4" and can be used as the socket. For the graduated cylinder, a good choice would be to use a large syringe, like the one pictured below. You can contact [[Support@FarmersEdge.ca]] to have one shipped to you.

The first step will be to unplug the tipping spoon sensor so that none of the water we run through the station during calibration will be show up as rainfall in FarmCommand Remove the control board cover by pulling the tab on the bottom towards you and sliding the cover up

Unplug the wire connected to the "RAIN" port on the bottom of the control board by pushing the tab on the top down and pulling the plug out

Now we're going to check if the calibration is accurate by slowly pouring water in the rain collection bucket and listening for the click of the tipping spoon tipping 10 clicks of the tipping spoon means the calibration is accurate and no action is needed

Measure **55ml** of water in your measuring device and slowly pour the water in the rain bucket If you're using a syringe, pull the plunger out and let the water flow freely from the bottom of the syringe **Don't pour directly into the hole in the center of the bucket**, that can cause the water to overload the tipping spoon and you won't get an accurate reading - instead, pour off center and let the water run down the bucket into the hole Listen carefully for the clicks of the tipping spoon - if the count is higher or lower than 10, the calibration needs to be adjusted

The first step to calibrate is to remove the rain collection bucket by twisting it counterclockwise and lifting it off the station

Remove the tipping spoon assembly by loosening the Phillips screw in behind the tipping spoon

Once the screw is loose, the entire assembly can be lifted up **Be careful to pay attention to the wire still attached to the tipping spoon and don't pull too far**

Turn the assembly upside down and you'll see the head of the set screw you need to adjust

Use your 1/4" socket or screwdriver without the bit to turn the set screw Turn it **clockwise** to **increase** the number of tips Turn it **counterclockwise** to **decrease** the number of tips **There is no estimate of how many turns equals one tip, this is a trial and error process where you'll need to adjust slowly**

Put the tipping spoon assembly back in place and tighten down the screw holding it to the station and put the rain collection bucket back on the station

Repeat step 4 and if you still don't count 10 clicks, continue to repeat steps 5-10 until you do

Once you have 10 clicks, plug the tipping spoon sensor back in the control board and put the cover back on and you're finished with the calibration

Calibrating the Rainfall on a Davis Weather Station

Lukas Hanson
12 steps
24 seconds