W-8681 anemometer disassembly
The W8681 wind speed sensor seized up. I had no doubt that the cause would be the ball bearing cage as had happened earlier with the wind direction indicator. I carefully prised the cups from the top of the unit. Unfortunately not carefully enough though and the plastic spigot holding the bearing cage broke off. Having had past experience of trying to glue plastics I decided to give that idea a miss and dismantled the unit.
After taking it off the mounting boom the cover underneath can be seen to be held on with three small screws. Inside there is a circuit board carrying a reed switch held on with two more screws.
The magnet which operates the reed switch can be seen along with the broken off spigot stuck inside the bearing which itself is stuck inside the top piece of the sensor which carries the wind cups. I drilled a small hole in the top of the unit and used a nail to drift out the bearing cage.
W-8681 anemometer repair
The ball race was reluctant to free up so I soaked it in WD40 overnight. It was still stiff. I eventually freed it up by putting a bolt through it, mounting it in an electric drill, and spinning it with the bolt held stationary in mole grips. There are no pictures of this as, sadly, I have only the single pair of hands. It was a crude attempt and although it did free up the bearing even after spraying with white lithium grease and further spinning it was not completely friction free. There was also some damage – the small metal shroud on one side came out. At this point I had a few options. I looked on eBay for a replacement bearing. There was no exact match but one I could have used – it had the necessary 10mm outer diameter although the inside was only 3mm. I also looked for a replacement aneometer and surprisingly there was one. Unfortunately at £25 I considered it too expensive but the seller also had a WH1090 which is an update on the W8681 (also known as the WH1080) and that unit had a console with adjustable contrast. I decided to buy one and retire the W8681 sensors at least – I am hoping to be able to use both consoles. I did, however, complete the repair.
I picked a coarse threaded bolt and by careful choice of drill size was able to use it to cut its own thread in the drilled out plastic base. After cutting the thread to length I bolted the partially freed bearind to the top of the base, pushed on the cup carrier, and put a patch of gaffer tape over the hole. If I had intended a permanent fix I would have used Araldite to block the hole. I could actually have swapped the bearing with that on the wind direction guage as the slight stiffness may even have improved that but as a replacement was on order I didn’t bother.
I have since found that Maplin stock replacement parts for their own version of this weather station – stock code N82NF with a current price of £2.49 If these had been available at the time and I’d known about them this page wouldn’t exist. If you take this route you may want to check the readings – if there is an inaccuracy from the different sensor Culumuls offers a multiplier which could be used to correct it.