The fan that I use the most in my office/3rd bedroom seems to seize up regularly and then needs to be taken apart so I can drip some 3-in-one onto the bearings.
Normally I have to do this every year, but this year I have done it twice.
I ran it without the cover to allow the oil to soak in well and noticed that the motor windings get too hot to touch. The heat then conducts along the shaft which is also hot, which is why the bearings are drying out I guess.
Is this normal ?. Is it the downside of a cheap desktop fan ?. If so I might bite the bullet and get one of those expensive Dyson fans (if I could be certain that it would last). Or is there a better oil that is more heat resistant ?.
It's a 2 speed fan. Not sure how the slow speed is activated. Does it engage different windings or is there a resistor somewhere ?
Firstly, these are probably Oilite bearings, and that means when all the oil leaches out they are basically useless. I had a Morphy Richards fan heater that did this, and oil as you say is only a short term fix. Unless you can knock out the bearings and get some new ones in then its probably junk. The windings do run hot in induction motors. The speed is controlled by reconfiguring the windings and their phase, its probably a shadowpole induction motore, similar to the sort you used to see on record changers. Dysan, well they are quieter and you do pay a premium though. I'm not convinced they are really any better than a traditional fan myself, but there is no visible fan to get dirty and need a clean I guess. Brian
My fan takes a grease kit, and it needs a bit of a stir right now, as the gear box is warming up (signs of friction).
The place that sells replacement parts for electric lawn mowers, had grease kits, and they would sell whatever was on the market at the time. ("Small appliance grease kit"). This means some of the grease was very nice, and some was "cheap shit". Doesn't matter once the lid is screwed down and you can't see it.
Motor speed can be done with just windings. I have one motor here with a proposed four speed windings, but two of those speeds would be too low for purpose.
If they were to do motor speed with a resistor, it would kick off some amount of heat, which you would notice. Using a resistor is a method from the past. It's not the notion of "efficiency" when you're caught doing that.
My desktop fan uses 35W of lekky, just as a reference for whatever you're driving. The shaft has visible wear on it, so it cannot last forever now. It's probably been used on a daily basis, for 30 years or so.
The plastic on the fan, broke, so I had to bodge a DIY solution to continue using the fan. So now it has a wooden base, and wooden vertical support, and just the motor cover plastic remains of the plastic bit.
When a device uses oil, the oil spigot has a wick down the shaft, those need oil roughly yearly. If an electric motor runs blazing hot (some do), they can run hot enough to actually burn up the cotton wick (now the reservoir has no "capacity"), and then the motor needs *weekly* applications of oil. This is why a grease bearing is so much nicer. You just run it for a number of years, until you can feel heat, and it needs to be re-packed.
Even my electric lawn mower, needed the gear box repacked. I was sharpening the blade one day, and noticed an abnormal amount of rotational friction. And the mower was a lot happier after being repacked. I bet not many in the audience have used an electric lawn mower long enough, to need a repack :-)
One thing to know about grease, is biological things like to grow in grease. The result can be quite unsavory. This is why, if dipping your hands in a grease bucket, you have to be careful to not transfer something back into the grease, that likes to eat grease for lunch :-) It's just the smell that will bother you. Gross. So when dipping stuff out of buckets, don't transfer some residue back into the bucket, for fear of introducing biologicals. I even had that happen to a small container of hand cleanser.
I was able to get more use from oilite bearings in a fan. I balanced a soldering iron tip on the bearing with the help of a retort clamp, with the motor shaft vertical, then oiled the bearing several times allowing the oil to sink in, hopefully into the oilite pores.
Geoff Drage aka Raden used to tell us WD and 3 in 1 were not really suitable for oilite bearing bushes. From memory he recommended a product called Anduril (?) and used it for boiler fan motors he reconditioned.
I'm sure I replied to this already. Chances are these are oilite bearings that have run dry, oiling is only a temp fix, you either need new iolite bearings or chuck it away and buy a new fan. I had a Morphy Richards fan heater with these bearings, and it would only run for a few weeks after the oil had gone from the material of the bearings and you oiled them. The heat evaporated the oil. Brian
HomeOwnersHub website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.