Stripped gears

[herman munster]

What am I doing wrong? First off I'm a Noob with helis, I've a little experience with a Falcon3D, was able to hover and some FF. Any way finished building the Hurri following all the videos(Thanks Finless) and took it out to teat hover it and before I could get it into a good hover the front gear stripped. I replaced it with a Revco gear took it out and managed to get a short 30 second low hover and set it down then gave it throttle again and the gear was stripped again. I'm running it stock except have the Z20-Kv motor, 15T pinion, 68t 1st gear,61T Main gear. Any help would be gratefully appreciated, I'm dying to get this flying and this problem is really frustrating

[mysticmead]

sounds like you have a gear mesh problem.. and when you switched to the Revco gears, did you switch to the pinion that is made for those gears? if not, then that's why you stripped the revco's.

[mysticmead]

post some more info on your setup as well. which Z20 did you get? the 980? or bigger? IF you got the 980 and use the 15T/68T/20T/61T you'd have a head speed less than 1500rpm

the smallest Revco pinion I know of is a 18T

[Mikej]

What am I doing wrong? First off I'm a Noob with helis, I've a little experience with a Falcon3D, was able to hover and some FF. Any way finished building the Hurri following all the videos(Thanks Finless) and took it out to teat hover it and before I could get it into a good hover the front gear stripped. I replaced it with a Revco gear took it out and managed to get a short 30 second low hover and set it down then gave it throttle again and the gear was stripped again. I'm running it stock except have the Z20-Kv motor, 15T pinion, 68t 1st gear,61T Main gear. Any help would be gratefully appreciated, I'm dying to get this flying and this problem is really frustrating

If you are using the Revco gears then I am fairly certain that you have to use the Revco pinions (and I don't think that they do those in 15 tooth). I think that the Revco and standard gears have a different module which would explain why the second one stripped. As for the first one, was it one of the OK gears or one of the older ones - though to be fair even an old one shouldn't strip in simple easy usage - perhaps your engagement is a bit too loose ?.

Which KV Z20 motor are you using ?

Good luck.
Mike.

[herman munster]

Originally had the stock OK gears with a 15T pinion, then stripped the gear so I went with the Revco gears with the Revco 19T pinion. and the motor is the Z20-980Kv

[Mikej]

Herman,

68T with a 19T pinion should give about 1,800 hs so that is ideal, how are you setting your pinion back-lash ? What throttle and pitch curves are you running ? How tight is your belt ?

Cheers,
Mike.

[herman munster]

Herman,

68T with a 19T pinion should give about 1,800 hs so that is ideal, how are you setting your pinion back-lash ? What throttle and pitch curves are you running ? How tight is your belt ?

Cheers,
Mike.

I set the pinion backlash the way Finless explains in his video I suppose I could have it too loose, how can you tell if it's too loose or too tight? As for throttle curve 0-65-80-90-98 and pitch 40-45-50-75-100 in Normal(didn't get to try idle up) The belt I get about a 1/4 inch deflection up by the front pulley

[Mikej]

I set the pinion backlash the way Finless explains in his video I suppose I could have it too loose, how can you tell if it's too loose or too tight? As for throttle curve 0-65-80-90-98 and pitch 40-45-50-75-100 in Normal(didn't get to try idle up) The belt I get about a 1/4 inch deflection up by the front pulley

That all sounds pretty reasonable - I use slightly different curves, but not a million miles away, and belt tension sounds about right. Other than using the Finless "feel" approach (which is what I do also) is to put a piece of paper (a small strip just thinner than the gear) between the pinion and the primary gear, then slide the motor up until the pinion meshes with the primary gear, tighten up the motor mounts and then turn the motor to get the piece of paper out - basically the paper defines the gap in the meshing.

I'm struggling to think of other issues - I use a 50 tooth primary gear as with the standard 42T my Z20A 980 would rub on the frame, presumably you get a decent spin down if you get to spin her up (mine will carry on spinning for about 15 - 20 seconds). Presumably you have your belt with the twist the right way and only one turn of twist. Latest motor mount with the bearing and the longer shaft ?

Good luck,
Mike.

[herman munster]

That all sounds pretty reasonable - I use slightly different curves, but not a million miles away, and belt tension sounds about right. Other than using the Finless "feel" approach (which is what I do also) is to put a piece of paper (a small strip just thinner than the gear) between the pinion and the primary gear, then slide the motor up until the pinion meshes with the primary gear, tighten up the motor mounts and then turn the motor to get the piece of paper out - basically the paper defines the gap in the meshing.

I'm struggling to think of other issues - I use a 50 tooth primary gear as with the standard 42T my Z20A 980 would rub on the frame, presumably you get a decent spin down if you get to spin her up (mine will carry on spinning for about 15 - 20 seconds). Presumably you have your belt with the twist the right way and only one turn of twist. Latest motor mount with the bearing and the longer shaft ?

Good luck,
Mike.
I have a good spin down, belts the correct way, and latest motor mount so maybe it is just a mesh issue. I've new gears coming from Ready Heli so I'll try getting a better mesh this time hopefully that will fix it.

[ke6d]

I prefer the "feel" approach than the paper method because sometimes the gears are not perfectly round. It takes a bit more time to set it up correctly, but you want to "feel" a tiny play between the gear mesh around the entire main gear circumference. Adjust the mesh so that you still have a "tiny play" at the portion of the gear that is "least" rounded.

Once you satisfy with the mesh, slowly remove the the motor and mount, then lock down the screws with loctite. Try to feel the mesh again after locking down the screws to make sure that it had not move when you tighten the screws.

I had several hundred flight on my Hurricane at headspeeds from 1900 - 2300 rpm without stripping a single gear.

[BenHeli]

I too stripped the 1st main gear after replaced it and that was three weeks ago. Just too lazy to fix it and too busy flying the "other" 500.