Hello,
I was doing my first flights today. And guess what... I crashed !
The crash did happen because the quad flipped (fortunately I was landing and thus almost on the ground) at the same time that one propeller collet came loose off the motor's shaft.
I want to express here some real frustration toward 3DR because of a fault by design in their kit. I had indeed an issue with fixing tight this collet since the 3DR kit was delivered. Although 3DR reads and cannot ignore the massive amount of people loosing props with these stupid collet systems, I wonder why 3DR continues to deliver them. There exist much better propeller's mounts that can be screwed on the motor and that makes it impossible to loose it !
Since I already lost this collet off the motor's shaft during some previous bench testing, I paid extra attention and efforts to fixing it correctly before external flights: i used blue loctite, i made sure I screwed the collet tight enough, etc.
That this is really a mount's design issue : such a system cannot ensure with enough certainty, even if you fix it right, that you will not loose a collet.
Anyway, as a result I broke two propellers, I damaged the protective acrylic arch (glad I had it!) and the responsible collet is of course unusable. (I guess I can be happy it is not overall too much damage)
I would really like 3DR to take lessons of this and change their propeller's mounting systems in their future kits.
Do you imagine what would have happened if I had lost this collet higher in the air ? This is serious.
Hugues
Replies
DJI on their cheap little ARF Flamewheel kits uses motors and props that are positively located by their oval hubs.
The motors are of high quality and this system is virtually immune to prop loss (or spinning free) if securely screwed down.
MultiCopters really have special needs since they continuously support the weight of themselves hanging off of the props.
Most solutions are still inadequate hold overs from lightly loaded electric fixed wing planes.
Sorry for your crash- that always hurts and leaves a pilot a bit bewildered. When I started in on this project, I lost a collet and got a crash as well- that was a year and a half ago. My response was "Hello cyanoacrylate, how are you today?" I love what super glue can do. I agree about the screw on adapters- thats what I'm using now, but to get flying with no worries with the current setup just CA the buggers on. Removal of the collets after gluing with CA is easy too- heat up the collet with a small flame (bic lighter) for a few seconds and it pops right back off.
Hi Hugues,
Sorry to hear about your crash. Please follow the link that Andrew Chapman linked. As you'll see, it has be thoroughly thrashed out.
If you're still having trouble once trying the EFlite adapters, loctite on the TOP ONLY of the motor shaft and using a torque wrench to put it all together. I would suggest the Tiger Motors, that screw onto the motor.
However, the difference was getting a decent small torque wrench. Made all the difference.
I'm still looking into the Tiger motors, but now for different reasons than just to stop a prop from coming off.
Good luck and happy to help you privately if you wish.
Cheers,
David.
Luckily I haven't lost one of these yet, but I also strongly dislike them. They simply are not a good solution. I've had trouble tightening them sometimes because I can't get them to stop spinning on the shaft so I can tighten the nut properly.
Perhaps some bearing compound (SUPER loctite, don't use it on threads!) between the collet and shaft might help in the meantime? This is not exactly conducive to "remove props before testing" however.
Tell me about it. I had one come off during a demonstration on friday. I've passed on your angst.
Richard
Sorry to hear about your issues with your motors and props.
I have been using the collets that shipped with my quads and hexs without incident. Here are a few things that I have done to reduce the risk of them coming loose:
- rough up the shafts slightly with sandpaper (as Thomas mentions below)
- be sure to use loctite on the threads (I also use the blue)
- be sure that you are using the correct prop center spaces for the shaft size, I flew a few times without them and the props spun loose ending in crashes or near misses to my head
- ensure that your props are properly balanced, extra vibration through your airframe can cause a number of issues
- I also add a small dab of loctite onto the shaft of the motor for a little extra grip
Hope this helps you!
@Hugues,
Sorry to hear about your crash due to a collet coming off of one of your motors.
I am curious why you continued to use that particular collet when you state that it came off during bench testing. It sounds like you should have stopped at that point and determined why the collet was defective and not fly with it later.
I have used collets on my model airplane motors and on my quads and have yet to have one come off of the motor shaft. The threaded propeller mounts that you refer to, IMHO, have excessive runout that will cause the motor upper bearing to fail much sooner due to increased lateral vibration of the motor shaft.
When attaching a collet to a motor shaft, I always rough up the motor shaft with 100 weight sandpaper and cleasn it thoroughly with alcohol prior to attaching the collets. Also, I occasionally run a pull test on the collects to ensure that they have not loosened.
Just a thought.
Regards,
TCIII
http://www.diydrones.com/forum/categories/diy-drones-rants-and-rave...
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