I know a motor thread exists but this one is for a particular application.

I am tired of buying oscillating fans that are made of plastic similar to ice cream containers (read = cheap) and that have crappy motor bearings that wear out very fast. My use is very prolonged hours (to send hot air from the second storey to the first of my house). I have a nice wooden box fan my grandfather made, but it has the wrong motor (spins in the wrong direction  and much too fast, it is too noisy). I would like to find a suitable motor (a speed similar to the lowest speed of an oscillating fan) with good bearings and running on 120V. Single speed is fine as long as it is slow enough. I have looked on eBay before, but would like your opinions first.

There is no hurry, the fan in question is in storage at my parents, we'll have to find it first.

Thanks in advance for your responses.

Have you tried a plug in dimmer to slow it down? Even when not that much efficient for an induction motor, it usually works. Ans it is not worse than the "slow" setting on most of the fans.
Then with many motors, you may reverse them - by swapping the direction of the stator coil, or (with some) even just by reconnecting the capacitor or auxiliary winding. For the help with that, I would have to know more details about the motor...

Not a good idea to connect an induction motor to a dimmer-bad for the motor and dimmer.Could cause either or both to burn out.The motor can overheat becuase it is not getting proper voltage or waveform.You would need some kind of VFD device for this purpose-Variable Frequency Drive.

I think midved ment a Fan speed controler,  even that get mistaking for a dimmer switch.

Thanks for all your replies, however I am looking at a replacement motor and variable speed is not required. If the new motor has multi-speed capability with different wires, I would connect the lowest speed only. If at all possible, I would prefer not to open up the existing motor. It might not be possible right away as I have to find said fan beforehand.

The fan speed controllers are nothing else than regular dimmers (the basic circuit is exactly the same), only the fan controllers have either a snubber circuit to suppress voltage overshoots from the triac when switching OFF the holding current, and/or "snubberless" triac type (low Ihold, rated for avalanche breakdown). But with decent dimmer design (with the EMC filter) the snubber is necessary anyway (due to the filter inductance), so it should work just fine.

Of course the motor get distorted waveform, but that usually does not pose any problem, the motor operates at increased slip anyway. So if that is problem for the motor, you can not use any of them anyway. But the fans are usually high slip motors, so do not have such issues...

The only practical difference is the range: For a dimmer it goes to really minimum conduction angle for a minimum light, for the motor speed controller it does not go below about 40% power. The reason is, the motor looses it's power way steeper, so below that it just does not rotate, so with a "dimmer" you would have just fraction of the control range useful for the speed control.

And here I would expect the regulator would be set once for the required speed and then enclosed into the fan box, so for that the limited part of the dimmer range is still good enough.
I think using such regulator would be easier than searching for a multi tap motor of useful power (in order for the speed levels to work, the motor has to be perfectly matched with the fan rotor, otherwise you either overload the motor or it will spin too fast even on the lowest setting)

Would a rheostat be a better choice for speed control ?

Would a rheostat be a better choice for speed control ?

No, way too lossy (a 40W fan motor operated at half power would dissipate about 30W on the rheostat and another 10W in the motor; yes, the total is higher than the motor at full power, due to the reactive power; with the dimmer you have just that 10W in the motor)...

Maybe a ceiling fan wall switch with variable speed ?

Maybe a ceiling fan wall switch with variable speed ?

For this application I would rather say just the regulator part from the ceiling fan switch - the purpose is to set the speed low once and keep it like that forever and not let every curious toddler play with it...

But would it work ? I'm rethinking this project and might consider wiring a variable speed control.

Why not?
I did many such regulators myself, both for shielded pole, as well as capacitor phase shift fans. Just the usable knob range was about half (setting to "half" power means the fun run very slowly).
A normally 2500rpm fan (cheepeese Tesco small desk model) on the regular incandescent Ikea dimmer (just readjusted to have all the useful range over the whole slider length of the pot - there is a trimmer inside for the minimum power adjustment) starts even when set to just about 60rpm (barely moving the air).

Of course assume the bearing in the fan is OK, so the only resistance the rotor has to overcome is the aerodynamic drag of the fan propeller itself (so proportional to square of the speed, so quite steeply changing; the bearing friction means constant drag, independent on the speed), as the regulation works on controlling the torque rather than the speed (so without the propeller it spins at full rpm all the time).

Some "fan controllers" have the switch off position at the "full power" end of the range, so when you turn them ON they are always started at full power to overcome the initial bearing friction, but  I've never met any fan really needing it, unless it was in the state to seize after few hours by itself anyway...