Motor keeps falling out of the Motor Mount

[nadeema]

I have built my very first foam plane using the FT speed build kit for the Nutball, but it is yet to get off the ground. One thing after another keeps going wrong, so I am learning fast about things that should have been obvious to an experienced RC flyer but were not to me. The latest issue is that whenever I try to take off the motor falls out of the motor mount. I am using the HobbyKing "HexTronik 24gram Brushless Outrunner 1300kv" (http://hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=48047), which has these two tiny screws that are supposedly used to keep the motor attached to the motor mount (image attached), but no matter how much I tighten these screws these do not seem to be tight enough and end up loosening when the throttle is increased.

Is there a trick that I am missing to securing the motor shaft to the motor mount?

Also, the last time the motor shaft fell out of the motor mount, i lost one of the two screws - can these be purchased separately or do i have to get a new motor now?

If I get a new motor, are there ones that do not have this problem and perhaps use a different method of securing the motor to the shaft?

Thank you all very much for any of your suggestions.

 

[Freaky_1]

You might want to file a flat spot on the 'shaft' for the grub screw to better bite into.
You DO want blue loctite.

 

[nadeema]

Where is the loctite applied? Only on the tip of the screw, or all over the shaft? If I apply it all over the shaft, than I guess the motor shaft will never be removed from the motor mount- is that ok to do?
Thanks.

 

[Tactical Ex]

Where is the loctite applied? Only on the tip of the screw, or all over the shaft? If I apply it all over the shaft, than I guess the motor shaft will never be removed from the motor mount- is that ok to do?
Thanks.

You will want to dremmel a "flat" into the shaft where the screw goes or the locktite wont make a difference. Apply the locktite to screw before screwing it in and that should be enough. It will hold well but you can still screw it off if needed.

 

[Freaky_1]

Just a tiny drop on the threads of the screw to keep it from vibrating loose.

 

[Craftydan]

Some Local Hobby Shops (LHS) will stock the small grub screws, but if yours doesn't the tiny screws can be hard to find.

if you can find out what size hex key it takes, you're most of the way to finding it. From the ones I've played with it's likely a M3 grub screw (which typically accepts a 1.5mm hex key)

They're pretty inexpensive when you can find them . . . online you're practically guaranteed to pay more for shipping than a pack of screws.


Now is the motor never getting secured tightly or is it working it's way loose after a flight?

The former is hard to deal with. The latter requires a drop of locktite on the grubscrew threads just before installing it.

 

[nadeema]

The motor falls out before the plane takes off; basically as soon as the throttle is revved up.
I found some other screws in my toolbox that do fit the hole, but these are the normal metal screws and not these "grub screws" - that is, they do not have flat ends on either side.
What I am worried about is having to drill into the shaft as someone above suggests, since i might cut into the wires.

 

[Tactical Ex]

...
What I am worried about is having to drill into the shaft as someone above suggests, since i might cut into the wires.

You are mis-understanding what we are talking about when we say that you need to "drill into" the shaft. Watch this video

http://www.youtube.com/watch?v=sf08HYt9gg0

at the 3:26 marker you will see what is called a "flat" grinded into the shaft (usually a 3mm wide shaft of steel) which is just as described "a flat portion of the round shaft". The flat grub screws sit flush with the flat piece and limits the rotational movement of the shaft without the rest of the pieces connected to the grub screw from moving with it. it also stops anything from moving up and down the shaft which is the effect you are looking for.

You will not be cutting any wires if you cut the shaft the way you are supposed to, there wont be any wires near where you are cutting period.