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        Discussion Blade CX lower rotorhead reassembly: careful with the upper set screws

#1 cbiffle Feb 04, 2007 04:49 PM

Blade CX lower rotorhead reassembly: careful with the upper set screws
 
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Just a note for the CX/CX2 owners out there.

When reassembling your CX, do not tighten the lower rotorhead's upper set screws all the way. They're long enough that, thanks to the alignment hole in the outer shaft, they can actually reach the inner shaft.

This will couple the motion of the inner and outer shaft, eating away your horsepower with friction, reducing thrust, and greatly increasing wear. If you've recently reassembled the lower rotor head and have noticed that it takes more stick to hover, that your motors are getting hotter, or that your battery life is mysteriously lowered, this is worth checking out.

I've been doing freelance tuning of CXes in my area, and I've found telltale scoring on a couple inner shafts. Picture attached.

#2 Twidget II Feb 04, 2007 06:44 PM

Thanks for the heads up!

#3 thomasora Feb 04, 2007 09:38 PM

i suspect that this would be the case on a Lama v3 too?
thanks!

#4 Lou Feb 04, 2007 10:08 PM

Quote:

Originally Posted by thomasora
i suspect that this would be the case on a Lama v3 too?
thanks!


Yes, these are know issues with the inner and outer shafts for both the Lama and BCX.

If the Inner shaft has a bend/curvature to it the effect is more noticable. Sometimes the two lower screws on the lower rotor head will score the outer shaft, this generally happens when the 2 upper screws have lost their purchase to the holes in the outer shaft.

Often what you will here is a metallic squeal or a rapid thump. All you can do is back the screws out a bit and make sure the inner shaft is not bent.

#5 N429EM Feb 05, 2007 11:32 AM

If you back out the screws, does this in essence loosen them and they can fall out? Or, do they not seat against a shoulder or something? Would it be advantageous to shorten/grind the end of the screws, so they don't protrude in so far?

My BCX should be on its way shortly. And, I'm trying to get as much heads up as possible.

Thanks,
E J

#6 cbiffle Feb 05, 2007 11:46 AM

EJ,

The screws tap into an alignment hole on the outer shaft, which is how they enter it and reach the inner shaft. If you back them out to clear the inner shaft, they still seat against the wall of the outer shaft.

(They ship this way -- E-Flite's quality control for the CXes seems good. This is only an issue if you reassemble the lower rotor head yourself.)

I'm not sure if grinding down the screws is a good idea; right now, all four lower-rotor screws are identical and interchangeable, which is awfully nice.

You're wise to gather info before the CX arrives. I think a lot of folks are down on the CX (and, likely, other micro helis) because they didn't take the time to learn it.

73

#7 N429EM Feb 05, 2007 11:58 AM

Thanks, cbiffle.
Anxiously awaiting my BCX.

E J

#8 thomasora Feb 05, 2007 12:43 PM

hey EJ,

where in silicon valley are you in? i am in san jose... was just wondering: if there are any LHS around that have esky parts? i own a lama v3 and couldn't find anything for it in south bay....

thanks
tom

#9 N429EM Feb 05, 2007 02:09 PM

Hi, Tom.
Uh, location is Sarpy County, Nebraska.
I'd say that's a ways from silicon valley. :eek:

Have a safe flight day,
E J

#10 thomasora Feb 05, 2007 02:22 PM

oh sorry EJ.

i guess i am asking the question to a wrong person....
but EJ, how's the weather in Nebraska now? any outdoor flying opportunity at all?

and, 73, where in silicon valley are you in? know of any LHS around? Thanks!
Tom

#11 N429EM Feb 05, 2007 02:47 PM

No, prob. Jus' playin'.

Anyway, it's :censored: cold. Haven't seen above freezing for over a week.
And, this Saturday is our Winterfest. Take-off, 360 degree maneuver of some kind, and land. Done. My daughter is gonna be sorry, she's the Winterfest Queen.

hehe

No biggee. It's a lot of fun.

E J


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