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Old 12-23-2010, 08:10 PM   #1
trickybit
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Default Stiff tail? Perhaps a defect has been isolated.

Both OnTheSnap and myself, as well as others on the board, have noticed that after some replacement parts, the Protos tail isn't as silky smooth. And coincident with that, we've experienced tail kick-outs and other tail mischief.

Some have purchased the full-on alloy tail assembly from Infinity, but the problem didn't go away. I personally threw a BLS 251 at the problem, for the (expensive) win.

But after talking with Alex (OnTheSnap) I took mine apart in every combination. I found that even removed from the tail shaft, the grips/hub/slider assembly felt stiff, if and only if both links were connected.

I then got out my scanning electron microscope and discovered a misalignment on the pitch slider that could explain a lot, including the Infinity tail not helping if you use your existing slider.

The pictures tell the tale. For workaround, I backed off each ball link 1 full turn (and used a drop of CA to keep them in place). It seemed to help a bit, but again, my BLS251 was doing fine.

The pictures also show this particular slider has been munged a bit; I don't think this could be munge-damage, but I do need somebody to confirm they see the same defect on their own slider. I don't have any crash part sliders around to compare.

With the grips set aside, you can fold the links up together and see they don't align. It's not 100% clear that this much deflection could cause blow-outs, but it's the first observed candidate I'm aware of, since the c-shaped pitch actuator was found out-of-plane some time ago.

The third photo above is the opposite side, which looks more or less square.
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Old 12-23-2010, 09:34 PM   #2
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Interesting find. But I have one that was bind pretty bad when you rotate the pitch plate boss. And the issue you show is not present on mine. The arms are both square and bring them together at the top shows they line up perfectly.

I installed a new pitch plate assembly and it does bind a little but not anywhere near the previous one did. I also limited how much the pitch plate boss rotates around the brass bushing by inserting two M2x3 grub screws in the channel.
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Old 12-23-2010, 09:49 PM   #3
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I just checked two used pitch plate assemblies and a brand new one that I received a couple of weeks ago. And none of them have the problem with the arms.
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Old 12-23-2010, 10:22 PM   #4
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OK, thanks. I'll pick up a new slider sometime and hope all problems go away.

I appreciate your checking.
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Old 12-23-2010, 11:59 PM   #5
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Quote:
Originally Posted by trickybit View Post
OK, thanks. I'll pick up a new slider sometime and hope all problems go away.

I appreciate your checking.
No problem. Make sure to rotate that pitch plate boss while moving the tail rod at the servo end with your hand. The amount of binding will vary from part to part.
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Old 12-24-2010, 02:24 AM   #6
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I didn't find any issues with the pitch plate, in spite of it being scuffed up.
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Old 12-24-2010, 03:48 AM   #7
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Quote:
Originally Posted by alexf1852 View Post
Interesting find. But I have one that was bind pretty bad when you rotate the pitch plate boss. And the issue you show is not present on mine. The arms are both square and bring them together at the top shows they line up perfectly.

I installed a new pitch plate assembly and it does bind a little but not anywhere near the previous one did. I also limited how much the pitch plate boss rotates around the brass bushing by inserting two M2x3 grub screws in the channel.
I also use this kind of "tuning" and the tail is silky smooth now.
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Old 12-17-2012, 05:43 AM   #8
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Methodically I would first check the different components of the tail separately. Disconnect servo from pitch fork, fork from pitch slider, slider from blade grips. All running smoothly?

Then connect slider to blade grips. If it binds check if your tail grip bearings are seated correctly (pull hard on the grips). You already found what looks like a warped pitch slider arm, maybe you can bend the one arm back with a little hot air? If this assembly is smooth, disconnect grips from slider again.

Next connect the pitch fork with the slider (the two screws) to make sure that the alignment of your tail pitch fork is correct. The imagined line between the two fork screws has to be absolutely square to the groove in the tail pitch slider. MiniP kit has a special ring to put over the tail shaft to check if the screws of the fork are aligned, but you can check this also by moving the fork with the connected slider and manipulate it until the slider has no binding on the shaft (disconnected servo of course). Push / pull on the fork until you feel in which position the screws should be aligned to get less or no binding. Remove the 2 screws, rotate the fork around, warm one of the fork arms (I use hot air tip from my gas soldering iron) and bend slightly in your previously defined direction.

Reassemble, check again, repeat as needed. Worked every time for me, on both Protos and Mini Protos.

The idea of alexf1852 to use grub screws to prevent the slider from rotating into a position where it will cause binding is worth a thought too if you dont get it sorted with the above method. Thanks for sharing!

Cheers
dremel
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Old 12-17-2012, 06:25 PM   #9
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There is a Japanese sites that sells a machined pitch plate for the Protos...
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