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Revolution Models . CarbonXtreme . Midland Helicopters

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e-Minicopter Joker > Mini Joker bad pinion?
 
 
dreslism
Veteran
Location: Rochester Hills, MI

I have been flying my mini joker for AP for quite some time with lipos and 14 tooth pinion.

I just switched over to A123's, so I changed out the pinion to the 15 tooth pinion (part 965).

Did a couple of test flights and all was well. Did one AP flight, and all was well.

I just went to fly another AP flight, and 20 feet into the air, smoke is pouring out of the heli. I got it down OK, and checked and the belt off the motor was slipping in the rear and rubbing on the carbon frames and that was the smoke (the belt).

I just slid the belt back up, then hand turned the motor and watched the belt walk itself back off the pinion. Then I noticed that there is no lower belt guide on the pinion!!

See the orignal good pinion below on the left, and the one I just pulled off of the motor on the right. I cannot honestly say if there was a guide there or not when I put it on, but I can't believe if there was, that it would just "break" off, and break off clean. Looking at it closely, it looks as if there was nothing ever there.

Anyone else ever have trouble like this, do you guys think it was not there to start with, or could it have broken off that clean that I can't even tell?

Thanks,



--Scott
GreatLakesAP.com
09-05-2007 Over year old.
 
 
fergus
Veteran
Location: Ireland

I had a pinion for the toptail unit on my joker2 come apart in the same exact way. Part number 216.

It was through brute force on my part though as I could not get it off a drive shaft. The belt guide did seem to be a seperate aluminium piece with the two being a press fit. It was a clean break. Not sure if the motor pinions are made the same way.

I want to stress the part I refer to did not fail. I caused it to come apart.

Regards

Fergus
09-05-2007 Over year old.
 
 
dreslism
Veteran
Location: Rochester Hills, MI

Well, as far as I can tell, my pinion DID fail.

I asked fxaeromodels about it as that is where I bought the pinion from.

Their reply was

Quote 
you did something wrong on your setting. Gerd will answer you at runryder.

I put this pinion on the same way I did with the 14 tooth that I used for about 6 months of flights with no issues, so I guess I will now sit here and wait for Gerd to reply so I can see what "*I*" did wrong.

Either way, I just want to know so I can be sure it does not happen again.

--Scott
GreatLakesAP.com
09-06-2007 Over year old.
 
 
rroback
Key Veteran
Location: Irvine (UCI), Ca

I had a similar thing happen with my maxi joker, but it was on the bench. If your pinion is not set correctly on the motor, i.e. it is too high or low, and so the belt does not ride perfectly horizontal, then this can happen. even if on the bench it seems straight, it's good to measure the belt positioning, or just do a very quick run up and see where the belt shifts too. Make sense?

Rhett... I can't fly, luckily the HC Profi Can!
09-06-2007 Over year old.
 
 
dreslism
Veteran
Location: Rochester Hills, MI

Yeah, makes sense Rhett.

I'll have to wait till my new pinion and belts arrive before I can give it a go.

Thanks,

--Scott
GreatLakesAP.com
09-06-2007 Over year old.
 
 
tabbytabb
Elite Veteran
Location: seattle

Scott,

Sometimes they just break

I had a similar pinion on an old CX crack where the flange area meets the pinion. This allowed the thin flange part to turn independent of the pinion. Luckily I heard a funny noise and landed.

Hope the next one fairs a bit better


Cheers


Tabb
09-06-2007 Over year old.
HOMEPAGE  
 
 
dreslism
Veteran
Location: Rochester Hills, MI

Thanks Tabb,

Well I guess sometimes they do just break, but this being only the 3rd flight on it, I guess I would expect more from a $20 pinion.

I have never had a heli before where a pinion could come apart, and did not realize this one could until it did.

I'm glad it turned out OK with the mount and camera under there.

My eye will definitely be on that belt and pinion before every spool up now!

--Scott
GreatLakesAP.com
09-06-2007 Over year old.
 
 
pyaresquared
Senior Heliman
Location: Central Arizona

The flange on the tail rotor and the main motor pinions will come off--sometimes with very little stress. I received one from a supplier that apparently had come apart in the mail. It's too bad Minicopter can't figure out a way to machine them out of one piece of metal.

Regards,
Steve S.

Surfin' the gravity waves
09-06-2007 Over year old.
 
 
Gerd
Senior Heliman
Location: Vellmar/Germany

One piece pinion with flanges...please explain how you will do that...

We check each pinion with a thumb test that the flanges are fixed and the manufacturer of them works with very narrow tolerances, but we cannot X-ray them.
So I assume that loosed flanges will be fixed again with pointer beats, because I hear that only the second time now since 2004 (J2 introduction).
And as spares ordered belt wheels are unexpected rare, about 5 on 100 kits. I thought that people like to play with the ratio in the same way like Joker 1.

I am sure that this risk could be reduced to about zero when the belt is running fine.
So I try to explain how to justate the correct belt running:
- righturn mainrotor.
- static test: Turn the motor left/ccw (and NOT right and NOT the mainrotor!). Then you will see that the belt has a tendence in a certain direction, either upwards or downwards. Now try how strong is this tendence, so press the belt with the finger to the other side and when the belt is coming back within a short distance on the belt you must correct the axis of the motor. Use 0.1 - 0.2mm shims (first only 0.2 mm) that you place between motor and motor plate or between motor plate and motor carrier. Now check again and add/remove shims if necessary as long as the force on the belt to get it on the other side is is in both directions about the same. It is very important to mount the belt after a service on the correct side (that you can read for example the code on the belt), because from production it is possible that the teeth a sometimes a little bit conic (too small to see, but you can see the result of inverted belt). Try this now as long as you cannot longer see any tendence.
More you cannot do static.
- Dynamic test: Paint the inner side of the shims with a felt pencil and fly in the hardest way you will later fly. After flight both flanges should be removed from colour at the same distance, if not then you should add shims for fine tuning like before. Another method I have seen is to add bolts under the front end of motor carrier. This feature we will use in the Joker 3D and it can be upgraded.

For the tailbelt the situation is much different because it is turned 90 degree and so there is always a direction to the aluminium flange that cannot loose (pin). These pinions are sold in opinion to the motor wheels more often, so it is possible that something can happen here. But we could add a concave shim between pinion and bearing with the diameter of the flange instead #52, why not.
09-06-2007 Over year old.
 
 
pyaresquared
Senior Heliman
Location: Central Arizona

How I would do it? Why, I would hire a top-notch machinist like Gerd to figure out a way to do it. I don't know, maybe you could cast it.

Regards,
Steve S.

Surfin' the gravity waves
09-06-2007 Over year old.
 
 
dreslism
Veteran
Location: Rochester Hills, MI

Quote 
- Dynamic test: Paint the inner side of the shims with a felt pencil and fly in the hardest way you will later fly. After flight both sides should be removed from colour at the same distance,


Gerd,

Thanks for taking the time to reply and explain.

I want to make sure I understand the above. It says to paint the shims.

I think you mean paint the inner side of the pinion with the felt pencil, then after flying, the pinion above and below the belt should have the same amount of colour removed from the pinion? This would tell me that the belt is riding evenly on the pinion, right?

Thanks

--Scott
GreatLakesAP.com
09-07-2007 Over year old.
 
 
rroback
Key Veteran
Location: Irvine (UCI), Ca

I think the idea actually is that neither side is worn, but yes, he's suggesting the felt so you see what side the belt is riding on.

Rhett... I can't fly, luckily the HC Profi Can!
09-07-2007 Over year old.
 
 
Gerd
Senior Heliman
Location: Vellmar/Germany

Yes, correct, but only the flanges, not the teeth. Use a permanent felt marker. After this test you can clean the flanges with alcohol.
When the belt is running continuously against one flange and is causing friction, heat and vibrations there, the risk of a loose flange is of course higher. You must see removed color on both sides about the same than it is fine.
09-07-2007 Over year old.
 
 
rerazor
Elite Veteran
Location: Mich.

Gerd,

I think the translation from German to English is causing some confusion. The pinion has flanges, that is what broke. Shims are what you put under the motor to correct alignment.
09-07-2007 Over year old.
 
 
Gerd
Senior Heliman
Location: Vellmar/Germany

Posts above edited, thank you

Oh, when I use wrong terms, please inform me and I will correct it. Send a mail to info@minicopter.de, this is the fastest way to reach me.
09-08-2007 Over year old.
 
 
T-rexn8
Senior Heliman
Location: COLORADO

So how is this issue going Gerd?
Also what if anything has been done to the parts to prevent this?
I am about to spend the 3K+ to get one and I wanna make sure it is a wise investment.

Thanks

Flightpower Batteries
09-26-2007 Over year old.
 
 
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e-Minicopter Joker > Mini Joker bad pinion?
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