Iris Assembly

My new Iris just arrived today and have started to put it together. I have a question to all you who have one up and flying.

The small prop shaft bushing that goes into each propeller is a bit on the tight side. Is this normal? Can it only go into the propeller hub one way? Mine seem to go in with the good side going in first.

Also how far down should the prop sit? Should it go all the way down to the bottom of the shaft? I don't want to force it if it is not required, but I think if there is some wear happening down the track the propeller can then be loose on the motor shaft and the nut would then not be holding it hard against the motor?

Any feedback would be great.

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  • Update on this issue.

    All good. Screwed the bushing down with the nut and wrench supplied. Went over the motor shaft okay and now is down hard against the motor housing. Prop went on and tightened down over the bushing. Felt like it should so I am happy with the set up now. Have put some thread lock on to ensure they don't come off when not expecting. Sorry 3DR but maybe you can change the instructions in the manual slightly. Might make it easier for everyone. So far so good. Time for same flight training. Thanks to all who read and replied.

  • Good to hear I was not the only one who had this minor problem. Not sure why they had to make the bushing that tight against the prop shaft. I managed to get two of them down hard against the motor housing, but the other two I was a bit worried that if I forced the issue, the prop bushing and prop might split due to the extra tension. I was thinking of using a longer wrench but thought if the manufacturer wanted me to put that much torque onto the nut, they would have supplied on a foot longer.

    The thing was so tight, I thought that the fine thread on the shaft might even strip, then I would be trying to get 3DR to send me a new motor. I can hear the tech now.... "if you knew it was tight, you should have called us for a new bushing instead you've stripped the shaft and now you have to pay for a new motor instead"

    I'll struggle on and hopefully it all works out. Standby copter fans.

  • Great timing on your question.  Although my IRIS arrived a couple of weeks ago, yesterday was the first day I had any time with it.  I ran into the same issue as you.  I followed the suggestion as below from AKRCGUY to push the bushing on the shaft by itself as far as I could, then put just the nut over it and screw the nut down, pushing the bushing down.  Then I removed the nut, and put the prop with lock washer down on top of the bushing.


  • Try twisting the prop on the shaft as far as it will go until its down enough to get a prop nut on, then use the prop nut to take it all the way down to the hub.  Now remove prop nut and install star washer and then prop nut again.

    • Thanks AKRCGUY for the advice. You don't think that the bushing will bulge and make it difficult to get the prop back over it? If not, I will give it a go.

  • Yes they are tight, and the props have to sit all the way down. some guys will use a small knife like an x acto blade to clean the hole out just a touch to make it a little easier to put over the prop shaft. also using a rag or glove makes it a little easier holding the blade when tightening. Just make sure you tighten it down so the spacer and blade sit flat on top the motor

    • In about 80 missions I have never lost a prop or prop nut. Ditto the same advice as Nitro has given. I use the prop nut to drive the prop and the adapter down all the way. I always check the prop nuts and very seldom did they need tightening. I also use the star washers that came with the Iris.

      You can also use these self locking nuts for extra insurance. see pic below.


    • I was going to add some thread lock to the nuts for security. I would have thought that the counter clockwise motors would have left hand threads on them. Maybe that's just too hard to organise in mass manufacture operations. I would be interested to see the stats on those who have lost props which ones came off?

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