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Other › 700MX broken shafts
06-03-2012 12:43 AM  6 years agoPost 1
danwr

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Maineville, OH

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I put together a Rave ENV with a 700MX, castle 120HV2, AR7200BX, Align servos powered by a Hyperion 2S life RX pack. All parts used except life pack and AR7200BX which are new. On about the 10th flight the power cut. I was low and was able to flip it upright but it landed hard and broke a landing skid. Repaired. Read about problems with auto bearing lining so I removed/cleaned and properly replaced. Took motor shaft out and reinstalled to make sure it hadn't slipped. Resoldered all wires to make sure joints good. Took the Rave out and after a few easy flights I was near the deck again and the exact same scenario. Power loss and I flipped it upright but landed harder. Broke struts, blades gone and main shaft. Get it home and I found out the 700MX ashaft had broken near where the pinion bolts on. Order all the parts including shaft and repair it again. Take it out again flying really high and just loops/rolls/tumbles. 3rd battery and same thing, power cuts. I auto in without damage and find that the motor shaft I just installed is broken.

How could this be happening? 1975 headspeed and relatively gentle flying.

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06-03-2012 04:53 AM  6 years agoPost 2
flyride

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Salt Lake City UT

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That is crazy!!! Did it just snap off?

and the blonde said "RECTUM, Hell damn near killed em!!"

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06-03-2012 04:56 AM  6 years agoPost 3
danwr

rrApprentice

Maineville, OH

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Yep. 5th flight or so after repair. Suddenly no power. Auto and find shaft broke.

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06-03-2012 02:43 PM  6 years agoPost 4
VKGT

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Sanford, NC

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That is crazy. I've never heard of this happening before? I'd contact Align and see if they would replace it

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06-03-2012 04:39 PM  6 years agoPost 5
misskimo

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Alaska 17 years, before mississippi for 31y

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T

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06-03-2012 05:18 PM  6 years agoPost 6
WrenFlyer

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Mississippi

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Align can't seem to get past this....a video from 4 years ago.

Watch at YouTube

Mr. Haney

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06-03-2012 05:46 PM  6 years agoPost 7
misskimo

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Alaska 17 years, before mississippi for 31y

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06-03-2012 05:51 PM  6 years agoPost 8
4cyclic

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Montreal, Can. and northern Vermont

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tight mesh ? also you're running a support bearing on the ENV ?

Life is meaningful flying helis.

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06-06-2012 08:29 PM  6 years agoPost 9
Rob43

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Midland, MI USA

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Have a pic of a failed one? Where did it fracture? I'd like to see what the fracture site looks like. It could failre in torsion, bending, or a combination.

Rob

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06-06-2012 10:06 PM  6 years agoPost 10
misskimo

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Alaska 17 years, before mississippi for 31y

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06-07-2012 04:15 AM  6 years agoPost 11
Rob43

rrKey Veteran

Midland, MI USA

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True, especially if there is not a counterbearing support. It's almost a guarantee it will fracture from bending stress with the stress riser at the diameter step. I don't believe there is a concave in the step on my 700MX. Since it is intended to rest in a 700e with counterbearing, they would not expect deflection from bending. Without deflection, you would not get the bending fatigue. That is why I wanted to see a pic. Origination marks will tell the story.

Rob

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06-07-2012 04:33 AM  6 years agoPost 12
danwr

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Maineville, OH

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It broke right above the cutout for the pinion.

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06-07-2012 05:06 AM  6 years agoPost 13
BladeStrikes

rrElite Veteran

Shelby TWP,Mi

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Looks like the shaft is dark (hot spot) where the break is..Maybe a bearing or something not lined up correct.Ive seen all kinds of different motor shafts snap (NEU,Scorpion,Align ect..) because it wasn't installed correct (motor not lined up/binding,mesh too tight,pinion slipping heating up the shaft ect..).If your not even beating on it like you said,something isn't right with the install.Really can't see 2 shafts snapping during 10 or so easy flights..

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06-07-2012 05:46 AM  6 years agoPost 14
misskimo

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Alaska 17 years, before mississippi for 31y

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06-07-2012 06:38 AM  6 years agoPost 15
BladeStrikes

rrElite Veteran

Shelby TWP,Mi

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Yeh! Motor is porely made by the looks of it. Wonder if you can slap a stronger shaft on it?
How can it be poorly made when people beat the living snot out of them without issues?
But I don't use cheap motors either
Your post is more of a brand fan post and no help to the OP because even high dollar motors had shafts snap because the install wasn't correct..

If his 700MX snapped the shaft with 10 easy flights like he said,this one shouldn't have made it through half this flight if it was poorly made like you said.He has something going on making the shaft snap

Watch at YouTube

When you get dark areas around the shaft like in his pic,its because something wasn't lined up right or mesh could be too tight..When metal bends over and over,it weakens where the dark area is and lets go..
Bend a metal clothes hanger a few times,the color changes dark where the bend is..If you keep bending it,it snaps easy..

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06-07-2012 03:25 PM  6 years agoPost 16
Rob43

rrKey Veteran

Midland, MI USA

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The pic is not nearly clear enough to get too scientific. However, the origination site appears to be on the surface of the shaft. Most likely bending fatigue. My guess is there's either not a counter bearing, or if there is, the motor is misaligned to it. If it were torsional, we'd expect eveyone to be snapping them...not just the OP.

Rob

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06-07-2012 08:21 PM  6 years agoPost 17
Richardmid1

rrProfessor

Leeds, England

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Surely the rave has a support bearing?

60% of the time, it works every time!

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06-07-2012 08:22 PM  6 years agoPost 18
danwr

rrApprentice

Maineville, OH

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It does have a support bearing. At this point I feel confident that I misaligned or diddn't handle mesh properly.

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06-10-2012 04:55 AM  6 years agoPost 19
ragtop

rrVeteran

salt lake city, utah, usa

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i broke a 700mx 530 kv in my gaui x7 doing aileron tictocs.

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06-10-2012 07:09 PM  6 years agoPost 20
GetToDaChopper

rrElite Veteran

Las Vegas , NV

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if it's discolored (Dark blue) then there's your real problem..... i said if........

and that comes from very high heat.....

    ▲
  ▲ ▲
▲ ▲ ▲ One of a Kind !!!

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