Topic: Calibrating Tipping rain gauge (see-saw)

[Weatherwx85]

Hi,
I am trying to calibrate my rain gauge, I have started with a 5ml syringe (weighed to confirm 5g water) and have adjusted the screws until it tips at roughly 5.44ml. However to do this I notice the screws are not level, one is all the way down the other is up by a turn or two. The ISS is perfectly level so I know it isnt that. I am currently testing with a water bottle with hole in with 544g (544ml) of water in to see if I get 20mm of "rain". I just wanted to check if the screws should be different or roughly the same with regards to turns. Obviously will see what happens with the current test but thought I would post this while I am waiting

Thanks

[CW2274]

I am currently testing with a water bottle with hole in with 544g (544ml) of water in to see if I get 20mm of "rain".

Unless I'm missing something (certainly possible), shouldn't 544ml (which is indeed 1" of rain for a Davis bucket) equal 25.4 mm?

[Weatherwx85]

My math could be wrong

544/5.44ml = 100 tips

100 * 0.2 = 20mm

[johnd]

IMHO: Forget trying to calibrate buckets with a syringe - there are reasons why this is not a good approach.

DRIP 544ml into the cone steadily/slowly and see if you measure 25.4mm rain - it doesn't then matter whether you have a 0.2mm (127 tips) or 0.01" (100 tips) increment gauge.

[Weatherwx85]

bugger will start again, was getting 19.8/20.2 mm on a few tests and thought that was correct  

[CW2274]

IMHO: Forget trying to calibrate buckets with a syringe - there are reasons why this is not a good approach.

As an end-all-be-all, absolutely agree, infinitely too small of a sample size. However, to get the spoons to tip as close as possible to the same amount, I think this is a good way start before moving on to a much larger sample size.