tecboy

Does anyone knows why these pinion gears' teeth bent?

aircrash

I think the major problem they have is they have worn a lot.
Not so much bent but worn.

They wear out sooner if:
1. you have applied grease or any other lubricant. As the dust & dirt can stick into and all these become a grinding paste. Then they wear out in no time.
2. Wrong mesh. They are either different in pitch/mod (gear mesh type) or you have left a bad mesh out of adjusting the motor.
3. Worn gear. It wears out the pinion. Especially if it does not spin even.
4. Motor`s shaft does not spin even. They will be worn out more in one side than the other.
5. Poor quality.
6. You have installed a less teeth pinion than it was designed for.
7. You have installed a much more torque motor than it was designed for. And you apply sudden throttle input increase all the time.

barak1001

Looks to me like your pinion isn't making good contact with your main gear. So just the tip of the pinion is contacting the main gear and the further out you get on the teeth the easier they are to bend and the faster they wear.

When you set your gear mesh put a piece of paper (standard paper, like a piece of copy paper) in between the pinion and main gear. Then push the pinion into the main gear crushing the slip of paper between. Hold it as tight as possible to the main gear and tighten down your motor screws. Then spin the motor/main gear to get the paper to push out. That should give you a perfect gear mesh.

tecboy

I tried that before with a paper in between the main gear and pinion gear. If the both gears are too tight to each other, the brushless motor will not spin and if too lose that brushless motor will spin inproperly. It is hard to get the gears not too lose and not too tight inorder to get a normal flight.

barak1001

You need to spin the gear and fine the spot that's closest to the pinion (gears are never perfectly true) and put the paper at that point. That way it won't have any tight spots.

erdnuckel2

Tony,

does the "gears are never perfectly true" apply to absolutely every possible gear - also the CNC milled ones (and those are manufactured by quite a few companies)?? Are the CNC milled one - to your experience - at least truer (more true?? - which one is it?) than the injection molded ones??

barak1001

I don't know of anyone that makes a main gear from metal. They are always plastic. You'll never find a metal to metal gear mesh on an RC chopper. Even in the case of a CNC autoration gear on a 450 the tail assembly gear that the gear comes into contact with is plastic.

Plastic can be near perfect, but usually isn't. Your pinion gear will always be metal, your main gear will always be plastic. That gives the drive train a point of failure in the hopes that it will reduce damage and repair costs in a crash.

aircrash

You can make a CNC gear even if it`s out of teflon, delrin or any other plastic type.
I used to make some teflon ones and some aluminium ones for my 1/8 formula 1.

CNC milled plastic gears are no superior to the injection moulded ones though.
If only the material is good and the injection moulded process is high quality.

The reason that the gear is always plastic is for the reduced friction.
A metal to metal needs lubrication.
A metal to plastic does not.

Now lubrication to the gears means that dust, dirt and other particles will stick into the gears along with the lubrication and they will form a grinding paste.
So that`s why you`ll never see a metal pinion to a metal gear in a electric heli.

Another reason is the reduced noise level, and as well reduced vibrations.

barak1001

I doubt I'd trust a CNC plastic gear. Think about it. When it's being cut out of the block there's always the chance that it will be weakened from the cutting. I'd much rather have an injection molded gear.

tecboy

Thanks you all for helping me out. I just hope both my main gear and pinion gear will last longer, if I tighten correctly. I hate keep buying new gears.

tecboy

I was wondering. Why can a pinion gear made of plastic? Would plastic is stronger than brass.

aircrash

Forget about plastic pinions.
A pinion is small in size, so it weights too little.
If you want you can use a different make and hope to be more durable.

barak1001

Have to agree about plastic pinions, they are junk.

I fly alloy pinions on my 450 and I'm pretty happy with them.