CAUTION: Before actually mounting propellers make sure to test the motor operation to assure they run in the correct direction, else swap two leads on the specific motor to reverse its rotation direction until all match the picture. Wait with installing propellers until you see that the IMU and transmitter calibration look ok.  Once propellers are in place they represent powerful aviation stuff that can accomplish considerable lifting force, so unless you have everything looking right prior to propeller install, then motors running havoc in an unintended way could hurt both you, the ArduCopter and others. So take care and double-check your setup prior to running with propellers.

Propellers come as pairs in two sealed plastic bags. One pair is intended for running clockwise (front/rear) while the other pair backwards (left/right). Make sure you install them as shown in the following picture (the + orientation shown. Same rotation direction principle applies for X orientation as well) :


By rotating them in the shown direction make sure they are oriented to drive air downwards. Once you come as far as arming motors and applying some throttle, then double check rotation directions before attempting flight.

How to mount propellers on each motor axle:

The washer shall go into that hub recess.

You place it on top, then press it into the opening....

And here is how it looks with the spacer in place.

Now install the axle using both aluminium parts.

Propeller with the mount ready to go onto the motor axle.

This type of 2mm shaft screwdriver proved handy for tightening the nut

Mr Arthur P. Meiners have contributed this additional security advice:

* Put a small drop of locktite into the nut and start it onto the thread.

* Consider also to put some locktite onto the motor axle but make sure it does not leak down to the bearings.

* Position the prop adapter with prop onto the axle and carefully tighten the nut. Don;t use a very long-armed wrench. These aluminum thread's don;t like too much force. In addition excessive force can also negatively impact the strength of these EPP prop hubs. The adapter has to tighten onto the axle so that it sits tightly and the prop cannot turn on the axle. If the nut is also a spinner, that's all. If it is a normal nut and there is room, then consider adding a 2nd nut and tightening that onto the first. This provides additional security against the nut working itself loose in flight.

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Very helpful! I've added a link to this in the wiki here.
Awsome, just the information I need to finish up my ArduCopter tonight. Thanks!
One critical item missing from this very helpful propeller mounting tutorial: balancing of the propellers!

Unbalanced propellers can cause excess vibration and can lead to premature motor bearing failure.

Just a thought.

yes I noticed they come in sealed bags although my top-of-the-line ordered edition of the kit stated that propellers would be balanced as delivered. But it could also be these relatively small propellers are of good quality and any difference in mass would be negligible ? Also there could be a small slack in the plastic spacer center hole that throw the balance off. Worth monitoring. Maybe one could measure vibration by applying the tip of a mechanical micrometer against the aluminium arm end and see to what extent the needle vibrates ? There is a tutorial here:
Thank you, handy stuff.

I had a crash yesterday from a propeller coming lose mid-flight and I was hoping someone here could help me with some tips to avoid another scenario like this. Luckily I was over grass so I only lost a couple of props. I have a 3DR frame with the 850 kV motors and 10x45 EPP props. I install the props pretty much like shown here but I have been using a paperclip to tighten the spinner on the shaft. Maybe this doesn't provide enough force. As the picture below shows, the threaded shaft which goes on the motor shaft was bent at the point where it grabs on to the motor shaft. There was medium wind when I was flying so it may be possible I was putting a lot of strain on the props. But I still think it's odd that this happened and made me think it wasn't just from the fact that I didn't tighten it enough. It seems like it would take a lot of force to do this. Also, I haven't wanted to use loc-tite yet because I am still making a lot of PID adjustments and I want to be able to take off the props easily for testing and transportation. Anyone have any ideas why this may have happened and any tips as to what I can do to avoid it from reocurring?

That spread joint looks like a result of the crash. Do not try to re-use this particular axle as this joint could break in flight. Paperclip is way too soft for tightening. You need one of those japanese screwdrivers that come in cheap sets, the size that just about fit in the hole of the nut.  But not so tight that you strip threads or worse.

Another important ingredient is locking fluid such as Permatex or Loctite ThreadLocker, the Blue variant.

That prevents the joints from unscrewing. When mounting this way where the mount tries to hold on solely to the smooth surface of the chromed motor axle it needs both a tight fit and some help from the threadlock fluid.  There seems to exist propeller mounts that also screw into the additional threads on top of the "outrunner" motor housing and that would add additional safety I guess. I am surprised that is not the standard application. Grabbing smooth motor axles this way may not be the safest solution seen so I will look at other ways myself. Some in the community here may have expertise on this as well as on the ultimate thread locker fluid usage recipe.

If you use loctite can you still remove the propellers at the end of a day of flying? Or do you just normally keep the props on there and just remove them when you are doing maintenance?

I see there are better mounts available for safe install, such as this one:

after dealing with a broken prop at the field. i found out that when using the supplied props you end up with one dia of thread engagement. when using apc props you have 2 dia's which is better. went to my local hobby store and got a E-flight  adapter. after putting it on its real nice. sits down on the motor farther, has more thread and has a built in raised section so you dont have to use the spacers. im converting the other 3 soon.

After pushing the washer into the propeller hub recess, there is a space between the propeller and the lower aluminum part (shown in figure). Am i doing something wrong?


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