TT Tail Boom support; umbrella gear mesh issue?

[EjectEjectEject]

Originally Posted by holytrex

It's just a matter of getting just a tad off so it can seat right..
And I have also applied a little heat to the gears as they spin... With a heat gun.....

And that does a good job of getting rid of the intended rough spots in the mesh of the gears.... But it's just my opinion....

I guess I just like to look further into the problem. From having an engineer type background...

But of course you don't wanna take to much off so it doesn't utilize the means of the bearings... Duh.

All good - just puzzled as to why it's needed - I've not had an issue with the stock parts.

[holytrex]

Just cause of what the. OP has said and that I have also had experience with the same problem...
So I was just expressing what I have done...

But I'm glad it has worked out for you...

[EjectEjectEject]

Originally Posted by holytrex

Just cause of what the. OP has said and that I have also had experience with the same problem...
So I was just expressing what I have done...

But I'm glad it has worked out for you...

That's cool - not trying to criticise. I just wasn't sure if people were realising that these are in essence a press fit. The "problem" is only in the last fraction of a millimeter and it appears to be because people are trying to press these on with just "muscle power" rather than using a bit of mechanical leverage.

If they let the jaws of a vice loosely support the bearing side it's actually quite easy to pop a piece of wood on top and just tap it gently fully into place with a hammer.

[Michael bacon]

If that works for you great..But I ain't taking a hammer to anything on my bird's... I preference a more subtle solution..

[holytrex]

Originally Posted by EjectEjectEject

That's cool - not trying to criticise. I just wasn't sure if people were realising that these are in essence a press fit. The "problem" is only in the last fraction of a millimeter and it appears to be because people are trying to press these on with just "muscle power" rather than using a bit of mechanical leverage.

If they let the jaws of a vice loosely support the bearing side it's actually quite easy to pop a piece of wood on top and just tap it gently fully into place with a hammer.

You are very right For sure.... I just know that if that Bearing race get's out of it's shape in any way.... it could defeat the bearings Job in being truly Round..... But i just like to think of it as a more Tech Way....Just cause i'm on SSI and like to think of other ways to FIX or MOD My Birds....

Originally Posted by Michael bacon

If that works for you great..But I ain't taking a hammer to anything on my bird's... I preference a more subtle solution..

I will Agree on that as well

I like to "seat" all my Gears with HEAT... It works Great But They Gotta stay moving... And then it's like they just came FRESH out of the Mold again......And Smooth like a Baby's Butt...LOL

[EjectEjectEject]

Originally Posted by holytrex

You are very right For sure.... I just know that if that Bearing race get's out of it's shape in any way.... it could defeat the bearings Job in being truly Round..... But i just like to think of it as a more Tech Way....Just cause i'm on SSI and like to think of other ways to FIX or MOD My Birds....

I will Agree on that as well

I like to "seat" all my Gears with HEAT... It works Great But They Gotta stay moving... And then it's like they just came FRESH out of the Mold again......And Smooth like a Baby's Butt...LOL

Guys - honestly - you're over-thinking this waaaay too much.

To illustrate the point I made an 7 second video of all it takes to seat the gear correctly. The parts are already speced just fine - they really don't need sanding and/or heat. Nor do they need belting with a big hammer or anything else that's going to damage the bearing. There are many things on helis that need a tap or two from a small hammer to seat properly.

https://drive.google.com/file/d/0B2g...ew?usp=sharing

[Ed Olson]

Nice. Thanks for that quick video clip. Pretty much sums it up.

[EjectEjectEject]

Originally Posted by Ed Olson

Nice. Thanks for that quick video clip. Pretty much sums it up.

No worries Ed - glad to help.

[holytrex]

Originally Posted by EjectEjectEject

Guys - honestly - you're over-thinking this waaaay too much.

To illustrate the point I made an 7 second video of all it takes to seat the gear correctly. The parts are already speced just fine - they really don't need sanding and/or heat. Nor do they need belting with a big hammer or anything else that's going to damage the bearing. There are many things on helis that need a tap or two from a small hammer to seat properly.

https://drive.google.com/file/d/0B2g...ew?usp=sharing

That's awesome Brotha...... Thanks for your wise words....

You have summed it all up...... Thank you

But. To. Each Their. Own.....

[Ed Olson]

So a quick update here. I have flown a handful of times since noticing this issue. Last night I went out for an 11pm night flight and upon spooling up I noticed the sound was gone and the heads spins freely without any friction or snags.

[Flowers]

Originally Posted by Ed Olson

So a quick update here. I have flown a handful of times since noticing this issue. Last night I went out for an 11pm night flight and upon spooling up I noticed the sound was gone and the heads spins freely without any friction or snags.

What did you eventually do to fix this problem? Tapping it in with a hammer? I toon have this gear problem, tried the KDE update with the shim, but to no result.

[Ed Olson]

Nothing. It seated itself after a while. Until today when I turned it into a lawn dart.

[EjectEjectEject]

Originally Posted by Flowers

What did you eventually do to fix this problem? Tapping it in with a hammer? I toon have this gear problem, tried the KDE update with the shim, but to no result.

Usually it just comes down to basics - these things are made to very tight tolerances and you really shouldn't need other kits to get it to work.

Realistically, if the issue is confined to binding on the front umbrella gear then it can only be 1 of 2 things - either something stuck in the mesh or the horizontal gear isn't seated correctly. Even 0.5mm out will make a difference.

[Flowers]

Originally Posted by EjectEjectEject

Usually it just comes down to basics - these things are made to very tight tolerances and you really shouldn't need other kits to get it to work.

Realistically, if the issue is confined to binding on the front umbrella gear then it can only be 1 of 2 things - either something stuck in the mesh or the horizontal gear isn't seated correctly. Even 0.5mm out will make a difference.

I think you are correct. I'm going to check it again to be sure it sits 100% correctly. I keep thinking that this binding together with a too high gain setting is the reason I strip these umbrella gears. Thanks for the input. I'll keep you informed!

[EjectEjectEject]

Originally Posted by Flowers

I think you are correct. I'm going to check it again to be sure it sits 100% correctly. I keep thinking that this binding together with a too high gain setting is the reason I strip these umbrella gears. Thanks for the input. I'll keep you informed!

You're welcome.

Not sure how you manage to strip them - I've only ever broken 1 tooth after I bounced an auto. Other that that, no other issues on the 550. Changed quite a few on the 450, but only as a result of crashes.

They do get quite loose after a while, but I've never had a set let go (yet).

[PaoloFCantoni]

Originally Posted by EjectEjectEject

You're welcome.

Not sure how you manage to strip them - I've only ever broken 1 tooth after I bounced an auto. Other that that, no other issues on the 550. Changed quite a few on the 450, but only as a result of crashes.

They do get quite loose after a while, but I've never had a set let go (yet).

If you lose the antirotation pin - so that you are yawing uncontrollably in the air. When you hit the ground and the tail hits first and stops moving, even with TH on, you'll strip them...

Ask me how I know...

I think I ended up with 1 tooth on each gear.

Paolo

[EjectEjectEject]

Originally Posted by PaoloFCantoni

If you lose the antirotation pin - so that you are yawing uncontrollably in the air. When you hit the ground and the tail hits first and stops moving, even with TH on, you'll strip them...

Ask me how I know...

I think I ended up with 1 tooth on each gear.

Paolo

I've had mine pop out of the guide before flight a few times - luckily I've picked it up when I realised that it needed an abnormal amount of collective to get off the ground (if that's what you're meaning?) (not sure - can't see that causing yawing).

[PaoloFCantoni]

Originally Posted by EjectEjectEject

I've had mine pop out of the guide before flight a few times - luckily I've picked it up when I realised that it needed an abnormal amount of collective to get off the ground (if that's what you're meaning?) (not sure - can't see that causing yawing).

I lost the pin in mid-flight - about 2 mins in. Once the swash is rotating with the main shaft, you can't provide any counter-yaw so the heli starts spinning - the gyro is, by now, awfully confused!. I think I was spinning for about 3 secs under power before I realised it was a lost cause and cut the power and tried unsuccessfully (as one would expect) to auto in. You can't really auto a yawing heli - you need good control of the flight surfaces at the best of times. I've only managed one by accident on a 450X.

Paolo

[hubmod]

Originally Posted by EjectEjectEject

This is mine - off memory it's got one shim in there at the moment.

Since a couple of flights my T-rex 550 DFC Pro developed a strange noise when I fly backward-circles or funnels. I played with a lot of settings on the beastX and wasn't able to get rid of it. The umbrella gear setup has quite some play so there is the idea that the noise comes from that end. Would it help to insert a shim ? What size ? Or is it a better idea to change the umbrella gear ? Any help would be appreciated. If somebody want's to listen to the strange sound I can send a mp3 ! By the way, the problem is just an acoustic one, the tail holds pretty good !

[Ed Olson]

Yes...a sound bite is in order. What settings did you change? If its a flutter then turn your gain down a bit.