700 DFC tail issue

[dennisb]

Just wanted to give an update to the problem I had with the broken tail shaft. I ordered a new shaft and the KDE performance tail upgrade ( because my original one got damaged when the shaft broke). I reassembled the tail and did a test hover and there was so much vibration I landed it and started looking for the problem. I noticed that one of the tail grips had more end play than the other so I ordered new grips and a new rotor hub. Replaced these parts, checked the balance and had the same vibrations. So I read somewhere to put extra bearings on the TT which I did and had the same result. The last thing I tried was replacing the carbon fiber rapped tail tube with the aluminum tube that comes in the kit and all the vibrations went away. I was able to put my first flights on it this past weekend and other than just dialing in the 7200BX it flew perfect.

Dennis

[brwilkins]

Originally Posted by dennisb

Just wanted to give an update to the problem I had with the broken tail shaft. I ordered a new shaft and the KDE performance tail upgrade ( because my original one got damaged when the shaft broke). I reassembled the tail and did a test hover and there was so much vibration I landed it and started looking for the problem. I noticed that one of the tail grips had more end play than the other so I ordered new grips and a new rotor hub. Replaced these parts, checked the balance and had the same vibrations. So I read somewhere to put extra bearings on the TT which I did and had the same result. The last thing I tried was replacing the carbon fiber rapped tail tube with the aluminum tube that comes in the kit and all the vibrations went away. I was able to put my first flights on it this past weekend and other than just dialing in the 7200BX it flew perfect.

Dennis

Any chance that maybe your TT bearings were a little off in the CF boom? It seems odd that just switching from the CF boom to the aluminum one would change anything.

[dennisb]

Originally Posted by brwilkins

Any chance that maybe your TT bearings were a little off in the CF boom? It seems odd that just switching from the CF boom to the aluminum one would change anything.

No. I actually pulled it apart a couple of times to check just that before I switched to the aluminum tube. The carbon fiber tube is actually an aluminum tube that is wraped with carbon fiber. I plan on taking it to my friend shops and chucking it up between 2 centers to see if it is warped, that is the only thing I can think of.

[rando]

This is interesting. Isn't the tail shaft exactly the same as used on the v2 and v1? Could the higher tail speed of the v3 be causing this? I wonder if any v2 or v1 owners have seen this problem -- especially those that have upgraded to the v3 gearing.

[Generalx5]

Originally Posted by Starcruiser

If this is the CC ESC then you require the USB interface to download the logs and make changes to the advanced settings (governor etc...). I would suggest purchasing one as they are rather inexpensive compared to the ESC (like <$30, I got mine for $20).

IF the timing is not set appropriately this could increase the ESC temp and cause the shut down, this can be viewed in the log output as mentioned.

Hey I didnt have to buy mine, the CC Manual included a cupon to either get a USB interface free, or buy a field programming card for like 16 bucks or something. I got mine in the align Kit

[Helos4me]

Not to change the subject but what ever happened with QA and the tail rofor shaft?

[brwilkins]

Originally Posted by Helos4me

Not to change the subject but what ever happened with QA and the tail rofor shaft?

After I put on the KDE upgrade parts, I haven't had any more broken shafts. That's not to say that the KDE parts fixed the problem necessarily. I could have just gotten two bad shafts in a row.

Just my thoughts, so feel free to disagree, but both times my tail shaft broke, the little black plastic arms on the tail slider also broke. I don't know whether they were the cause of the shaft breaking or whether the shaft breaking caused them to break, but the KDE ones are metal with bearings on both sides. It seems silly to me that these arms are the only pieces of plastic on the tail assembly (other than the drive gears of course), so it made sense to me to change them out to the KDE metal ones. Like I said, no issues since swapping those out.

On the other hand, I've got a 550E and a 600E and both of those have the plastic arms and have never had a tail problem.

[Helos4me]

[PetJumper]

Originally Posted by brwilkins

It seems silly to me that these arms are the only pieces of plastic on the tail assembly (other than the drive gears of course), so it made sense to me to change them out to the KDE metal ones. .

Actually, the load on those arms is quite limited. It is just a push and pull from the blade grips. You will have a hard time pulling them apart by hand, because it is a very strong plastic compound. If they break at all, it will be at the very tip behind the screw.

The snapping of the shaft has caused the arms to break as the shaft didn't support rotor revos and the entire revo load bent the arms backward. By carefully inspecting the break area you will be able to identify that "bending" force pattern.

rgds
Peter

[Landonhunter]

hi, i just got the dfc and am worried if this is still a problem. i have no idea when the kit was actually manufactured.

[msallua]

64 flights here, 3D flight's ... no problem.. Touch wood

Just check and use a good amount of loctite in the grub screw that hold the tail rotor in the tail shaft.

Excellent Machine

[Dino Spadaccini]

Ok so you all know my self and a few team guys have been working on this issue what I have seen is some have it and some don’t, One of my Dfc does so that being said now let me tell you what I have come up with

On the heli that is good no Vib in the tail its a stock heli now on to the other one which is stock also here is what I have tried to find a solution

I want I found the difference is between the two helis was how I shimmed the main shaft, On the good heli I used the med shim that allowed the Jesus bolt to slide in easy with out any force or having to kinda screw it in. there is a slight amount of play in the main shaft up/down like a tick of play,

On the heli that had the vib I change everything out from the good heli to the one with the vib and could for the life figure out what could be causing this Until I swapped out the heads which included the shim and vib was gone, put the other head back on and vib back, I ripped the head apart and swap everything out still there until I just happen to pick the heli up and felt the small tick and it hit me, I put all the part back to the helis and shimmed the main shaft with a med shim and the vib was gone put the thick one back and it was there so now I swapped out tails and it seems no matter what tails I used the vib was there once I put the med shim in gone, now I put the lower bearing block in and did the test again with thick shim vib was there with the med shim gone.

So with all this being stated by me, here is what I am asking the ones with the vib check your shimming on the main shaft and see if you are using the thick one try the med one and let me know if that fixes the problem if so what I did to remove as much of the little play in the main shaft was to sand down the thick shim on a flat surface and keep fitting it until the jesus bolt went easy there is barley and play the reason I did this was I did have any of the thin shim to work with.

In closing play try and see what happens when you try this and please post here is I can see what some of you come up with

Thanks Dino Spadaccini

[msallua]

Dino,

My kit comes with 3 shim's:

1) 1.2
2) 0.8
3) 0.5

I'm using the shim number 3) 0.5mm

64 3D flights and no problem's with tail rotor shaft

And....Yes, sometimes my vertical fin has a little Vib, but sometimes don't have Vib

The Jesus Bolt in my kit fits perfect, slide in easy with out any force, no play.

I was thinking it was the stock tail blades , change stock rear blades for a EDGE 105mm tail rotor blades, but the small vibration also sometimes appears.

.....

I'm gonna try the medium Shimm 2) with stock tail blades

I hope the jesus bolt slide perfectly

[jimmitch]

My tail shaft just broke today . I have been flying it all summer with no trouble.Is Align giving any credit for the parts I need to fix it? These shafts must be defective . Is anyone making a better shaft for this heli?.I never had any vibration the thing flew rock solid.

[ddj74]

Originally Posted by jimmitch

My tail shaft just broke today . I have been flying it all summer with no trouble.Is Align giving any credit for the parts I need to fix it? These shafts must be defective . Is anyone making a better shaft for this heli?.I never had any vibration the thing flew rock solid.

Good luck with that. Think i read some using the nitro shaft.

[RV_7A]

I feel need to post this. As I am assuming the shafts are breaking at the set screw point. Look at the difference between these 2 shafts. If you had to guess, which one do you think would snap first if the set screw was very tight? With CNC machining today there really shouldn't be any variance between the two.

Jeff

[ddj74]

Originally Posted by RV_7A

I feel need to post this. As I am assuming the shafts are breaking at the set screw point. Look at the difference between these 2 shafts. If you had to guess, which one do you think would snap first if the set screw was very tight? With CNC machining today there really shouldn't be any variance between the two.

Jeff

Did you even look at this whole thread? First page shows the shaft breaking where its machined to a lower diameter. Not at the set screw area. You cannot overtighten a set screw enough to break a shaft.

[ddj74]

Originally Posted by Dino Spadaccini

Ok so you all know my self and a few team guys have been working on this issue what I have seen is some have it and some don’t, One of my Dfc does so that being said now let me tell you what I have come up with

On the heli that is good no Vib in the tail its a stock heli now on to the other one which is stock also here is what I have tried to find a solution

I want I found the difference is between the two helis was how I shimmed the main shaft, On the good heli I used the med shim that allowed the Jesus bolt to slide in easy with out any force or having to kinda screw it in. there is a slight amount of play in the main shaft up/down like a tick of play,

On the heli that had the vib I change everything out from the good heli to the one with the vib and could for the life figure out what could be causing this Until I swapped out the heads which included the shim and vib was gone, put the other head back on and vib back, I ripped the head apart and swap everything out still there until I just happen to pick the heli up and felt the small tick and it hit me, I put all the part back to the helis and shimmed the main shaft with a med shim and the vib was gone put the thick one back and it was there so now I swapped out tails and it seems no matter what tails I used the vib was there once I put the med shim in gone, now I put the lower bearing block in and did the test again with thick shim vib was there with the med shim gone.

So with all this being stated by me, here is what I am asking the ones with the vib check your shimming on the main shaft and see if you are using the thick one try the med one and let me know if that fixes the problem if so what I did to remove as much of the little play in the main shaft was to sand down the thick shim on a flat surface and keep fitting it until the jesus bolt went easy there is barley and play the reason I did this was I did have any of the thin shim to work with.

In closing play try and see what happens when you try this and please post here is I can see what some of you come up with

Thanks Dino Spadaccini

This has been an issue before and talked about. What i've read its low grade steel...pig iron...

http://www.rcheliaddict.co.uk/align-...tml#post494543

[jimmitch]

I just sent pics to align I hope they stand behind their products

[lazsyss350]

I ordered the tail shaft from the chaos 700, going to give it a try and see what happens, I haven't had any issue so far with the align tail shafts but just to be on the safe side i'll try the chaos ones. http://www.scaleflying.com/Torque-Tu...t-_p_2096.html