Hello Everyone,

Ok the only crashed I get now are when a prop falls off the quad will in flight.  It has cost me two cameras and a good amount of embarrassment.  It only happens once every 15 flights but I hate it.  So has anyone ever super glued the collet prop ad pater to there motor?  It seems even if the motor goes bad at some point a new motor comes with a new collet adapter.


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Dan, at least you have the knowledge to recognize a defective component!  Gott sei Dank!

Until we can devise a suitable cage or 'ring prop' (been done for boats BTW), for our quads, the rotational forces exacted on the motors will continue to cause damage to our motor shafts if impacted (blade strikes).

Most of the local hobby shops in the US can get EFlite adapters in 2 or 3 days from their distributor. That depends, of course, on your location (and the shop's business attitude).

As mentioned previously, a sliding fit is preferred. What you describe with the 3.0/3.17situation is concerning. 'What's a few hundredths of a millimeter?' someone might say. A LOT when it comes to this situation.

The sketch above is NOT a sliding fit though the shaft pressed into the collet firmly. There would probably also be some scrubbing damage to the inside of the collet but that is minor compared to the bad fit.

Good thinking. Good luck and definitely let 3DR know about the eccentricity issue. They don't make the parts but their vendor should own up to the quality issue.


I know this is a little bit of a necro, but I wanted to post a follow-up, and I've seen a handful of posts on the topic in other threads as well.

I ended up going with the E-flite adapters ordered through my local hobby store as planned, and I've been fairly satisfied with them.  Because so many people here suggest it, I did use a little bit of blue loctite on the threads.  And I've had no signs the adapters loosening.

But the other day I got a little carried away tinkering with the PIDs and had a minor crash with a prop strike (vs. grass/dirt).  The prop was undamaged, but motor shaft was very slightly bent.  I didn't notice this at first, and continued to fly my quad after a quick check and PID adjustment (a later review of the logs clearly showed an increase in vibration).

Well, a couple minutes later one of the other motors came loose.  I landed before it completely let go, and put the quad back on the bench for a full check and repair.

Lesson #1: I should have put locktite on the motor mounting screws.

Lesson #2: locktite does NOT work well with the E-flite adapters.  In attempting to get the prop off the damaged motor, I had to grip the adapter with pliers and destroyed it in the process.

I disassembled the motor, straightened the shaft, reassembled with a new prop adapter, and went back to flying.  And started shopping for a better way to mount the prop.  I ordered some parts from rctimer to try out, and here is what I learned:

The 45mm shaft they sell matches the original shaft on the 3DR 850kv motor.  Even with the E-flite adapter, this leaves about 4mm of excess between the adapter and the top of the motor.  This excess just makes it that much easier to bend the shaft.

They also sell a 41mm shaft.  I ordered a few, and they appear that they will work well with the E-flight adapter.

They also sell a 37mm shaft, which appears to be the best length to use with the 3DR adapters (although I recommend against it for the reasons in my previous post).

And lastly, they sell a 31mm shaft, which is flush with the top of the rotor.  This works with their new bolt-on adapters., which fit the 3DR 850kv motors.  I ordered one of these to try, and put it on the motor for some bench testing tonight.  I have two minor complaints, but my overall impression is favorable.  I intend to flight test the adapter and probably order a full set.

My complaints are first that the spacer (needed for thin props like an APC 10x4.7 SF) has a large center hole, meaning it is about impossible to perfectly center, and second, with said props the prop shaft is just long enough to extend into the through-hole for tightening the spinner nut.  That can be fixed with a dremel.  Also note that the adapter does not seem to be available in a reverse-threaded version, which is too bad.

Lastly, I was curious about the weight; the bolt-on adapter is also about 3g heavier than the E-flite adapter, but the shorter shaft is about 2g lighter.

Hopefully this info will be useful if anyone else is looking for alternate prop adapters.  Note that if you want to change the shafts on your motors, you'll need some sort of press.  There are details/videos about how to do that if you search.

Excellent post. One question, you mention that 37mm was the best length, but did not recommend it. You mention something about a previous post. Could you explain?

You can use the following to press in and out motor shafts.

3/16 socket long
3/32 drift punch

I was referring to my post two posts earlier on the page.  Basically, I think the adapters that came from 3DR with the motors are poorly designed/machined and are not suitable for use.  And if you're going to go through the trouble of changing the shafts on your motors, you might as well get new prop adapters and use whatever is the best shaft for those.

I'm going to give the bolt-on adapters a shot, and (eventually) find out what kind of damage is done when I (inevitably) whack another prop on the ground.

I've not had any issues with loosing adapters. I've had issue with bent motor shafts. Thanks for finding replacement shafts.

I've used these in the 3DR motors with no problems.


DJI 2212/920kv motors are $24 each.  They have short shafts.  Their props stay on.


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