Saturday, July 2, 2011

Fixing my wobbly desk fan

I unscrewed and opened up my desk fan to try and see if I could keep it from being so loose and wobbly. I thought maybe something could just be tightened. I found that the looseness comes from two things: the arm that pushes and pulls the fan from side to side is purposefully designed to be loose, and the turning axle does not have a good fit. Since the first is on purpose because of how the fan is designed, I can't really fix that (bad design of fan, then?). The second is too hard to fix, since I can't easily make a new axle or add material to make the fit tighter. See the pictures below for more details on the various things I saw.

Overall Pictures

Here's the arm that pushes and pulls the fan side to side. It's the double-angled piece of metal that is attached to a large plastic gear and the fan's base. The gear turns and pushes and pulls against the base, which stays still, so the fan moves. One of the holes on the arm is oblong and both screws are very loose. This makes it flexible and not bind up when it moves through all possible angles, but also makes the connection loose. It moves fine, but it will wiggle a lot if touched.

Here's the switch, which looks like a variable resistor with 4 states.

Here's a closeup on the magnetic coils for the motor. The coils are the black plastic underneath the main metal housing and behind the large gear. Notice the laminated iron core going through the coils and around the motor to strengthen the magnetic field and reduce eddy currents.

Here's the inside of a gearbox that directs power from the motor/fan blades to the side-to-side motion of the fan.
The silver axle extending towards the viewer comes from the motor and is a worm gear. I don't remember checking to see if there was a worm gear attached, milled into the axle, or if there are indications of the end of the axle having normal screw threads. I wonder if the last option might be easier to manufacture.
The knob lifts the white gear up out of the worm gear, turning off this motion. This seems to be a good way of  getting "in and out of gear."

Here's the hole with the screw that holds the turning axis in place.

Without the screw.

Here's the tiny screw that is used for the above pictures. Not very strong, I would guess. Is this the source of the wiggle? Does it need to be tightened or replaced with a longer, bigger one? Further research indicates not really.

Here's the axle connection. The metal ring seems to a bearing so that things don't scrape too much.

Here's the axle after the screw is taken out. Now we see that there is a groove all the way around the axle where the screw fits in, keeping the fan attached to the base. So the screw and this groove are what take the weight in this area when the fan is picked up from above. Noting the size of the screw above, not a design I would trust.

Nothing much to see from this view.

Another axle picture. The bearing is sort of loose and slides up and down a bit, you can see the gap here.

I tried to get a picture of the other end of the axle to see how it was attached. All I can see is the hole in the metal where it is attached. Clearly it was put on there before the fan and motor assembly was attached to that large metal bar, because you can't reach it now.

Here's two views on how the turning gears engage and disengage. I've always wanted to see this from the inside. As explained before, this is all done with the worm gear that ultimately powers the small gear seen here. So it actually doesn't matter how these gears end up meshing. I would have thought that these were the gears to engage and disengage.

Here in the disengaged mode, these gears are still together, which doesn't matter.


  1. Fixing the fan yourself can be good if you know what you’re doing. Your desk fan might be old, that is why it’s starting to create problems. Maybe getting a new one can be a better move rather than fixing it again and again with the same problem. It can save you plenty of money as buying one can be cheaper than repairing it in the long run.

  2. I can see what you mean, but in general I would have to disagree. As you can see, this whole blog is about exploring and learning about technologies like this. Opening things/products up and doing that is called "hacking" by many people (see my post on the hacker/maker culture). This is great because it encourages learning by independence and not having everything being handed to us. I learned a lot by trying to fix this fan and I really didn't know what I was doing or what to expect, which is fine as long as you use common sense. And when taking many devices into account, it is usually cheaper to fix things yourself or buy replacement parts than having it serviced or than buying a new one. In this case, it didn't get fixed, but now I know what the problem is and I see that it's not worth replacing. I can tell that the problem isn't so bad after all and I'm more comfortable with the issues I have to deal with now that I know more.

    Another aspect to this is the belief that consumers should not be dependent on companies to fix, maintain, handle, and replace the products that they buy. There are companies that practically force this dependence on the consumers, which is unfair to the consumer who bought and owns the product. A well known organization that is helping people fix their technological devices (phones, etc) is iFixit ( They strive to decrease planned obsolescence and increase what they believe are basic consumer rights.

    So I hope you can see that, in general, fixing things yourself is found to be very valuable to many people and can be better than just replacing products.
    But I see that you are connected with a fan manufacturing company (, so that might have been your initial motivation for your post.