Secret Scotland

If it's secret, and in Scotland…

Anemometer gloom and joy

I picked up a cheap wireless weather station a few years ago, which has been less than successful, but for the money, does work well enough to stop me from looking for a skip to give it a new home. The ongoing problem is simply poor wireless performance, which stops and starts for no obvious reason. Range is not the cause, nor low batteries – it just stops and starts at random throughout the year.

Biggest disappointment was the early death of the rain sensor. Yes, I can look out of the window and see rain but… the system showed rainfall history and stats, which is handy. But the sensor just stopped being seen one day, and never connected again.

So, I’m left with things like wind speed and direction (and some derived quantities) temperature and RH, and barometric reading (and more derived quantities such as dew point).

Once a year, I have to take the head unit down and fit new batteries – remember… wireless.

This year, the thing was unusually dirty, with a lot of black dirt (maybe mould or moss) stuck to it, so a quick clean was in order.

This was fine, until the cloth I was using flicked a loose corner around one of the anemometer legs – and the cup snapped off.

I know how little force this cause, and I saw the corner of the cloth getting caught and dropped it – but I think that a few year exposure to UV had made the cheap plastic brittle, and it just separated without bending.

The way it broke the arm out of the edge of the cup meant there was not way to pin it or support it in some easy way, and the thin material had no strength. I did consider trying to melt the plastic and weld the part, but guessed this would fail as it only works if the right type of plastic has been used, and if it fails, the mess that’s left is even less repairable than what was started with.

As the weather was so cold, I decided to try a trick, and mixed up some slow-setting epoxy, which is almost solid when cold.

Heating this allowed it to be flowed into and around the break, but once it had cooled, the resin was so thick and the parts so lightweight) that it held them in place until it set.

After leaving it to cure for a few days, a gentle tap showed it had actually done the job, and the cup did not just immediately fall off.

I rebalanced the rotor to take account of the added weight of the resin on the damaged arm, and some weeks (now months) later still see it spinning away, having survived this year’s winter storms.

Anemometer cup repair

Anemometer cup repair – the one on the right

 

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March 13, 2014 - Posted by | photography | , ,

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