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700 Class Electric Helicopters 700 Class Electric Helicopters manufactured by Align, Tarot, SYMA, Airhog, Chaos, HK and similar.


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Old 01-11-2017, 09:59 AM   #1 (permalink)
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Default Trex 700x problems

Hey guys!
I just finished building my trex 700x. Everything fit pretty well, but I had an issue at the swash. I screwed the ball links in the outer hole, but one ball link broke apart and half of the thread is still in the swash.... May I use the inner hole? Or is it bad for flight performance?

I also have a problem with the main gear... After using washers to eliminate axial play and tightening the m4 socket screw, the main drive gear still has a little play, however the main shaft doesn't. Is it possible that the main gear has play on the one way bearing shaft?🤔

I hope you understand my problem and my bad englisch😆

Many thanks in advance
Moritz
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Old 01-11-2017, 06:30 PM   #2 (permalink)
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It should fly ok. Just be more careful threading the balls. Let the loctite do its job. You shouldn't have any up and down play on the main gear. Something may not be assembled correctly.

Did you disassemble the one way sleeve? If so, you may have removed and left out the large washer that belongs in there.
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Old 01-11-2017, 06:47 PM   #3 (permalink)
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Thank you!
Right! I disassembled the main gear. Tomorrow I will look for it again to check if sth is missing.

Moritz
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Old 01-12-2017, 06:33 AM   #4 (permalink)
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Another possibility is the radial ball bearings in the one way hub have slipped slightly, and this will allow some up and down movement.

Disassembling the one way hub, applying some bearing retainer Loctite, and re-installing the radial bearings should resolve it.
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Old 01-12-2017, 06:45 AM   #5 (permalink)
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Personally if you cant remove it i would replace the swashplate, yes it would fly if you set it up with the inner holes but... having just measured my 700x swash i can tell you there is an 18% difference in length between inner and outer swash holes from center of main shaft. This will give your main blade grips to much angle, of course you can still set 12 or 13 deg at grips but you will lose 18% of the available cyclic servo travel= lower resolution eg: fbl unit now has 82 points of servo ajustment, not 100. And of course 18% more load on the servo's.Possibly drill and tap a 3mm thread then find a new ball link to suit. The main gear should not have play at all. Good luck man you will love the heli it is epic.
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Old 01-12-2017, 08:19 AM   #6 (permalink)
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Thanks !
I just disassembled everything and checked that the washer is installed. I haven't reinstalled the bearings, because they were already tighten and installed correctly. I put everything back together and found the problem. The play comes from the place where the one way bearing mount is on the autorotaion gear.
May I try to fix it with washers in between?

Moritz
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Old 01-12-2017, 08:35 AM   #7 (permalink)
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Ohhh... just saw that the lower gear isn't all the way in the Mount. Thanks Derek! I'm now going to put it in correctly.
Moritz
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Old 01-17-2017, 04:12 PM   #8 (permalink)
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you might be able to remove the broken ball joint by getting a small left hand drill bit , heating to soften loctite and apply preasure on the broken ball joint with a drill in reverse ...or drill out and re-tap the hole ...
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Old 01-18-2017, 03:43 PM   #9 (permalink)
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I noticed similar play and just added a shim above the main gear.. works great no issues
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Old 01-18-2017, 04:01 PM   #10 (permalink)
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Thanks for all your useful tips. As dchekas mentioned, the play in the main gear came from the ball bearings in the one way hub. I heated them up, hammered slightly out ( maybe not the best idea, one bearing makes much more noice then they normally do. Maybe have to replace it?) and glued them in. After I put everything back together, there was zero play.


@heli addiction
18% is lot... need (want ) as much cyclic I can get. Think I gonna replace it, because I couldn't get it out with a drill...
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Old 01-28-2017, 11:53 PM   #11 (permalink)
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I have built several Align 700s, and they all required the swash balls to be in the inner holes. I don't know about the 700X specifically, so maybe Align has changed the grips and servo output arms, but the reason they had you use the inside holes was you got too much cyclic throw with the outer ones and had to set your FBL loops outside their optimum values. I agree that thei 700X manual shows them to be placed in the outer holes.
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Old 02-06-2017, 12:42 PM   #12 (permalink)
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Quote:
Originally Posted by heli addiction View Post
Personally if you cant remove it i would replace the swashplate, yes it would fly if you set it up with the inner holes but... having just measured my 700x swash i can tell you there is an 18% difference in length between inner and outer swash holes from center of main shaft. This will give your main blade grips to much angle, of course you can still set 12 or 13 deg at grips but you will lose 18% of the available cyclic servo travel= lower resolution eg: fbl unit now has 82 points of servo ajustment, not 100. And of course 18% more load on the servo's.Possibly drill and tap a 3mm thread then find a new ball link to suit.
This is incorrect. Moving the ball to the inner hole on the swash increases resolution. For a given amount of swash movement, the blades will move less.

I ran the inner holes on Vbar just fine. Outer holes were necessary on Brain2 to get good numbers.
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Old 02-06-2017, 12:54 PM   #13 (permalink)
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Quote:
Originally Posted by heli addiction View Post
Personally if you cant remove it i would replace the swashplate, yes it would fly if you set it up with the inner holes but... having just measured my 700x swash i can tell you there is an 18% difference in length between inner and outer swash holes from center of main shaft. This will give your main blade grips to much angle, of course you can still set 12 or 13 deg at grips but you will lose 18% of the available cyclic servo travel= lower resolution eg: fbl unit now has 82 points of servo ajustment, not 100. And of course 18% more load on the servo's.Possibly drill and tap a 3mm thread then find a new ball link to suit. The main gear should not have play at all. Good luck man you will love the heli it is epic.

Yeah I was kind of wondering about how you came to this number. From a recent post...I made, summs up my understanding...

Quote:
It is a tradeoff for controller resolution versus available throw. Closer to the servo spindle means the controller can use a higher resolution in its calculated commands. Problem is that you will eventually run out of motion throw.

Depends on what the controller wants for a good setup. I have run both inner and outer on a 550 e.

To far out and the controller needs to little range of motion to accurately adjust. It eventually comes down to servo speed and power, I think, you can run lower resolution if the servo can handle the power and speed needed to execute the commanded control.

Higher resolution is always better for any clocked Integrated Circuitry that utilize control loops. However, if you can only achieve 8deg. collective and 5deg cyclic, on the inner hole, the helo will probably fly very badly.
Third paragraph might be a guess, about the speed and power thing, but I am pretty sure about the rest. I think the outer holes are only there for crazy 3D capabilities, if you are a good pilot.... Align markets it as a "3D Helicopter" so it has to be able to perform. I never really noticed much difference, but then again I am no FBL controller expert.
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Old 02-06-2017, 02:56 PM   #14 (permalink)
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You are right there my mistake i was getting mixed up.
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Old 02-06-2017, 03:40 PM   #15 (permalink)
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Thank you for all your replies. I ordered a new swashplate just to be safe. I already checked all screws and than it happened I overtighten one screw... sorry for stupidity... there are two M2.5x5mm screws that go into the "CONTROL ARM Mounting Bolt" which is mounted on the right metal plate of the tail case. One of the screws is very tight, the other one has no grip at all in the aluminum. The inner screw broke completely. Do you guys have any idea how to fix that? Or is it possible to glue the screw in with green Loctite, although here is no inner screw?
Greetings from Germany,
Moritz
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Old 02-06-2017, 05:14 PM   #16 (permalink)
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I would always advise replacing it.

The question I always ask is, "Is it worth a $250 crash for a $20 part?"
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Old 02-07-2017, 07:46 AM   #17 (permalink)
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That's true... but the only way to replace this part is to buy the hole tail pitch. It's about 45$
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Old 02-07-2017, 11:15 AM   #18 (permalink)
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What part, exactly? Got a pic?
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Old 02-07-2017, 11:43 AM   #19 (permalink)
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The red marked screw is the one I overtighten. One of the inner screws in 144 is damaged.
Moritz
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Old 02-07-2017, 02:03 PM   #20 (permalink)
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you could try a left handed drill bit , if its not too tight .
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