Third time tail gear fix - sponsored by HomeDepot :)

[aliali]

well....the first time, i had a crash...and on of the thread was almost gone...second time, one screw could'nt hold it so i have put two thicker screws which lasted till today (just hovering couple of times)

now, here comes the third time....one of the screw head was cut due to the torque !!!
the rest of the screw was stuck in the thread....that was even worse.

i remember Chris mentioned earlier that if i can drill the hole bigger and use the thread maker...that idea came to my mind and i have bought a 8/32" thread maker and 3/8" machine screws...
drilled the hole and put a nut on top so the screw wont hit the shaft and tightened it up !

and now....its like rock solid with a single screw !!!

i have tried to drill a hole to remove the stuck screw but i was unsucessfull...


I am sure, Bergen will come up with some kind of mod to make the tail gear even better !....

[SeaHawk]

I have also had problems with those original screws getting stripped, and so did one of the previous owners of the Intrepid I just bought. My first attempts were to drill more holes and eventually they stripped too. My third attempt I stuck with original size screws, but JB welded them in place so even if they stipped, they would not back out. Not great workmanship, I'll admit, but most of Bergen owners seem to be heavy handed with 'gorilla grip' which probably is main contibuter to the stripped screws as we attempt to tighten then to point they 'won't come out'. Given we're not all perfect mechanics (though I'm glad I'm in good company) I would really like to see Bergen customer proof this design.

[v22chap]

Sea hawk
Bergen has found a fix for the gear box and us gorilla grip guys :)
Send the unit back to them and they will install a helicoil that will be better for ya ,, and it still uses the same size screw and won't pull out the threads as now the threads are stainless steel .
Here is a link to the helicoil repair kit explanation :
http://www.noblefix.com/helicoil.htm

[SeaHawk]

Thanks V22Chap, thanks for the advice and the link. I'm glad to hear that I'm not the only one Gorilla-gripitis. That really looks like the ticket for me and my swiss cheese tail rotor gearbox (lots more holes than the original two. With the helicoil solution, I should be able utilize one of the existing holes.

[kelly steed]

Broken screws,torque no,vibrations yes.one place to look is your torque tube,remove the tube spin complete unit in high point balancer .look for run out proplems,if you have to much, your input bearing outer race will be starting to wear in the housing.To fix try to get torque tube as true as possable,use red locktight for outer race.This worked for me. I now have four screws with blue locktight snug only. Hope this might help.

[rappy-60]

Hmm.. So I am apparently not the only one with this same exact problem. Those 3mm screws are just not enought to hold on the tail. This is how I fixed mine.

http://www.runryder.com/helicopter/t374170p1/


Dale

[v22chap]

No ,, no ,, no ,, it isn't a problem with the screws ,,, it holds on my other 3 birds,, It holds on all of Malories and Gregs birds .... You just have to learn how tight they have to be and not gorillia grip them in ... and then make sure your bird is all balanced good ..a vibrating tail will take any setup you have out when you are running that long of tail and blades.

[aliali]

pretty cool.....well done !

but, on another side....i am 99% sure, that its due to our own mistake....not a design fault...

there must be something wrong we are doing which is causing this problem....

this helicopter is an awesome design....only a very well experianced mechanical engineer with an excellent exposure to aeronautics can design such helicopter with all aspect in mind....the whole model is based on every single load/length/weight calculations....look at the workmanship, the precision and quality of the product.
i am sure they are using state-of-the-art softwares like solid modeler is capable of simulating the whole design in computer in 3D before its even built.
(i know this since 3D modeling and rendering is my profession and i work on Solid Modeler/Microstation/AutoCAD and 3DS Max). i am sure that the designer wont leave a simple screw if its not suitable.


although i am facing this problem....but, i am sure that its something to do with setting...

[kelly steed]

I agree with larry,a 3m srcew broken,or maybe a set of tail blades because the housing turned. is a pretty cheap way of telling you that maybe you have a proplem.you can put four 3m in the housing,that will fix that.Now it's up to you and your judgement.did I put the screws to tight, or is thier somthing I should be looking for.I have four 3m on my housing because I lost two in flight.Old threads were ok but I didn't trust them.Two are plenty strongh.if you do not over tighten or have a viberation problem.

[rappy-60]

Well after having the tail back out once, and then locktite'ing them in with green, and them still backing out, I opted to drill 4mm screws in and I have had zero issues since. Well that tells me that the 3mm bolts just don't hack it and that there is not enough meat on the EB tail cage to hold in the threads. Are you going to trust your bird to two tiny 3mm bolts when its flying 50+ feet in the air? Im certainly not after it backed off (thank goodness it happened on the ground) twice on me. I just assume to put a beefier 4mm screw in and make sure it doesnt back off or strip, which it doesn't.

Dale

[v22chap]

Are you going to trust your bird to two tiny 3mm bolts when its flying 50+ feet in the air?

Don't get me wrong here ,,not trying to be smart or anything ,, just honest .... but yes I do ... all 4 Bergens that I have ,,, from my 12 yr old 23 PUH gasser , to my Bergen "Turbine" all fly with the stock 3mm tail bolts and they fly 100 + feet in the air always ,, just ask Lou .
I should add that the 2nd Bergen I own and was the first I built and that I stripped out is now helicoiled ,,,but still to 3 mm ... once I learned how tight they have to be and to use red locktite and get all vibes out of the tail they have been fine.

And hey if it makes you fell better to have the extra large bolts and was capable of making it happen ... I 'm all for that too ,,,as that is half the battle flying helis ...trust in your equipment . I just don't want guys to feel they have to rush down to their work shop and start drilling and tapping out their gearboxes right away because 5 guys had their problems with the stock ones ,,, as there are 20 X more guys that are using the stock 3mm and not having any issues . :)

[ShawnK]

Are you going to trust your bird to two tiny 3mm bolts when its flying 50+ feet in the air?

Absolutely. I've had and flown 3 Bergens, and never once had a problem with those screws.

[kelly steed]

If you have proplems with 3m bolts,here is a nother cool update

[v22chap]

Now that is cool Kelly ,, never seen that done before ,, now all you need is another ball on the slider and you would have a dual driver for the tail ...... Hmmmmmmmmmm

[ShawnK]

I don't think it wouldn't work like that. On a single point slider, the pitch slider and the ball rotate on the output shaft to compensate for the arc of the bellcrank. Trying to put another ball on the opposite side of the slider would have the 2nd ball moving in the opposite arc of the bellcrank.

A dual-point slider has to have either an articulating link to convert the bellcrank's arc into a linear motion (like JR or Kyosho), or use pins riding in a groove on the pitch slider so that the bellcrank isn't locked into position with the slider (like Hirobo).

[v22chap]

Yep ,, you are right ,, as usual :P ,,, S

Although you might off set the top arm so it would rotate the opposite of the bottom and still get it to work .....
don't get in a twit ,,just messin with ya S

[ShawnK]

It is kind of a neat lookin' picture, though, I'll give him that. :YeaBaby:

[kelly steed]

Thats a chunk of fly bar threaded at both ends,some brass tubing for a spacer,bell crank bearings with 4mID,also spacer between bearing to make axel.works great.I needed extra weight to offset the 6000mah up front.

[rappy-60]

I just don't want guys to feel they have to rush down to their work shop and start drilling and tapping out their gearboxes right away because 5 guys had their problems

I agree, for those that have issues like myself then there are options available.

If you have proplems with 3m bolts,here is a nother cool update

nice kelly, I do like the added post on the tail.

Dale

[SeaHawk]

good ideas. Unfortunately, not everyone puts these things togeter perfectly, I must be in that catagory. And sometimes a little murphy-proofing doesn't hurt, especially if it adds to reliability and piece of mind. If a larger screw, red loctite, helicoil puts a bandaid on the real source of the issue, then so be it.
That being said, I'll make sure I go back and rebalance my tail components and break out the dial indicator for the torque tube etc.