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DIY Fixing the stress crack flaw
3447 28 2015-9-9
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ctonyperry
lvl.3

United States
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So, i just logged my 51st flight last night, at just under 6 hours of flight time and I am developing the dreaded stress crack manufacturing/design flaw. No crashes, only very gentle landings, no rough handling.I decided to take it upon myself to fix the shell myself since I don't really want to rely on DJI's customer service to remedy the situation for me.  I've heard that repairs take forever and I've also heard that it's questionable that they even warranty the shell against their own defects!? If Im gonna pay for it, I might as well get a shell now and just do it myself.


So,  I was taking the screws out to disassemble the shell, 2 of the screw recess just fell right off! UGH! Turns out they weren't cracked, they were completely broken.


With the realization that I am going to be on my own with this one I ordered a replacement shell.  My plan is to reinforce all the potential weak spots before I replace the current broken shell and put it all back together.


Does anyone have any input on what should I use to do this? Would 20 minute plastic epoxy be a good choice? Should I shred up some fiber glass into it? Looking for advice to keep it light while finding a way to prevent this inherent flaw from causing me problems.This, plus the gimbal roll problem that I have chosen to just live with are really souring my experience with DJI. I've purchased Naza flight controllers and a Ronin in the past....but the P3P might be my last DJI purchase.


2015-9-9
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jaronpv
lvl.4
Flight distance : 723776 ft
United States
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I purchased these:
http://www.uavbits.net/store/p28 ... orcement_plate.html

They have good build quality, are very affordable, and they spread the force out across the entire bottom of the arm instead of just at the recessed area of the screw holes.

Shipping was also very fast.   light-weight as well!   Definitely get these for the new shell.  

As far as the epoxy, it cant hurt since it will already be apart.  But I honestly think these Strong Arm kits would be more than enough.
2015-9-9
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astrostar
lvl.4
United Kingdom
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Plast-Aid is pretty good Plast-Aid website
2015-9-9
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ctonyperry
lvl.3

United States
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Thanks for the tips! Ill definitely check out the plast-aid. Anyone know of any STL files for those reinforcements? I have access to a decent 3d printer so I think Id just as soon print off my own.
2015-9-9
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Phantom Help
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ctonyperry@gmai Posted at 2015-9-9 17:46
Thanks for the tips! Ill definitely check out the plast-aid. Anyone know of any STL files for those  ...

http://www.thingiverse.com/thing:971151





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2015-9-9
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acenothing
Second Officer
Flight distance : 112185 ft
United States
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I agree that Past-aid is the best option.
2015-9-9
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ctonyperry
lvl.3

United States
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I just watched the plast-aid video. That stuff is impressive! When the new shell arrives, I am going to reinforce all the internal screw recesses before I move the guts into the it. Exciting! I've been building multis for years and I actually kind of enjoy this stuff ;).

2015-9-9
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walky
lvl.2

Australia
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I had all 4 arms cracked, 1 quite significantly with multiple cracks between screw holes. I have no confidence in waiting for a repair, or that any repair won't have the same issue down the track, and I didn't want to keep flying because if a motor lets go, it will either be crashed into the water and gone, or in a billion pieces with no way of ever proving the issue existed before the crash.

Min had 16 flights and 2hrs 12 mins on it, never landed hard, never touched anything but air with the arms/props etc.

I sent it back for a refund and bought an Inspire.
2015-9-9
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1111
Second Officer

United States
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Bondic around the stand offs and motor holes.   It works
2015-9-9
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mark1975
lvl.4
Flight distance : 92454 ft
United Kingdom
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^^^^uavbits.net work perfect cannot praise gary enough @uav bits.net
2015-9-10
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Msa2
New

United Kingdom
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Well had my p3 for two weeks and done about 3 hours flying and I got the dreaded cracks not a happy bunny
2015-9-10
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skadar
New

United States
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walky Posted at 2015-9-9 23:44
I had all 4 arms cracked, 1 quite significantly with multiple cracks between screw holes. I have no  ...

Dang, this kills me.  For the past week I've been struggling to pull the trigger on a $2000 P3 package, but this thread is shutting it down for me.  Sigh...
2015-9-10
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SpunOne69
lvl.4

United States
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I have had mine over a month, at least 30 to 35 flights...no cracks yet
2015-9-10
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liningiv
Second Officer
Flight distance : 329409 ft
United Kingdom
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75 flights before my P3P cracked, rear black motor arm, screw between lower and upper body.
I have used my own repair which has prevented any more damage, now on 120 flights, and when I have a month or two when I plan to have a break from flying, probably Feb/March I will send it for a body replacement.  
Just be aware that if you repair it yourself using glue or epoxy resin, then you have no warranty, period.
2015-9-10
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aburkefl
First Officer
Flight distance : 78612 ft
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Phantom Help Posted at 2015-9-9 17:49
http://www.thingiverse.com/thing:971151

Looks interesting, but I didn't see any hint of the price.

Art Burke - N4PJ
Leesburg, FL
2015-9-10
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gregg1r
First Officer

United States
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liningiv Posted at 2015-9-10 15:27
75 flights before my P3P cracked, rear black motor arm, screw between lower and upper body.
I have u ...

Don't know how your warranty works in the UK, but on the USA warranty page, DJI lists the "frame" as having no warranty.  http://www.dji.com/service/warranty-period

DJI rep, Tahoe_Ed has indicated that they will cover cracks not involving crash damage. I've heard three and six months.

Don't wait too long.
2015-9-10
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walky
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Australia
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gregg1r Posted at 2015-9-11 06:54
Don't know how your warranty works in the UK, but on the USA warranty page, DJI lists the "frame"  ...

They can't get away with that crap over here. In fact, we have laws that mean even after the statutory 12 months warranty has expired, you can still claim warranty if it was meant to be an expensive high end item, sometimes depending on what the item is and how it sits among it's industry peers, that extra warranty protection is available for another couple of years.

I have the maximum spec late 2013 Macbook Pro Retina which I bought at release in 2013, and the screen gave up last month. No Applecare (Nobody needs to buy it over here) and when I walked into the Apple store to put it in for repair, the guy looked at the model, saw the machine was a max spec model and just said come back tomorrow it will be ready.
2015-9-10
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Phantom Help
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aburkefl@gmail. Posted at 2015-9-10 16:53
Looks interesting, but I didn't see any hint of the price.

Art Burke - N4PJ

It's not for sale. If you have a 3D printer, you can download that model for free and print it.





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2015-9-10
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aburkefl
First Officer
Flight distance : 78612 ft
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Phantom Help Posted at 2015-9-10 20:17
It's not for sale. If you have a 3D printer, you can download that model for free and print it.

Thanks - have to scout my "local neighborhood" and see who's got a 3D printer! I wonder how long before the 3D printing/scanning will be ubiquitous?

Art Burke - N4PJ
aburkefl@gmail.com
Leesburg, FL
2015-9-11
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mvgossman
lvl.1
United States
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jaronpv@hotmail Posted at 2015-9-9 15:02
I purchased these:
http://www.uavbits.net/store/p28/Strong_Arm_reinforcement_plate.html

What's the "Strong arm for hardshell backpack"? Is there some flaw in the backpack too or is it for a special reinforcing strong arm that fits into this back pack? I have that backpack.

Haven't had any cracks yet. I think I came across a recommendation for wrapping a cable tie (aka zip tie) around the end of the arm to ward off the cracks, is there anything to this? Certainly a cheap option.
2015-9-28
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jaronpv
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mvgossman Posted at 2015-9-28 10:15
What's the "Strong arm for hardshell backpack"? Is there some flaw in the backpack too or is it fo ...

No flaw in the backpack.  The lip that the standard strong arm kit has can keep the backpack from fully closing.  It sounds like the standard strong arm kit, with the raised lip around the edge, is stronger.  It is the one I use.  The one for hardshell pack does not have the outer lip so that it fits in the backpack.    The cracks form, in my opinion, from the arm twisting under the force of flying.  Zip ties will not keep this twisting from happening, and will then crack.  The strong arm kit disperses all of the force from the motors across the arm, instead of having the force on only the plastic that surrounds the screw.
2015-9-28
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jaronpv
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mvgossman Posted at 2015-9-28 10:15
What's the "Strong arm for hardshell backpack"? Is there some flaw in the backpack too or is it fo ...

They did address the issue of having the lip gone by adding carbon fiber . so it will be sufficiently strong.  I highly recommend ordering the strong arms.  Keep your arms from cracking in the first place.
2015-9-28
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hummingbird.uav
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Flight distance : 6928517 ft
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Canada
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If there are cracks around the motor holding screws you need to do some serious repair or shell replacement.  However if the crack is in the screw hole that holds the shell together there is a simple fix.  I used 1/2" wide scotch tape.  I noticed when the screw hole tube is cracked the arm is more easily twisted.  Adding the tape made the damaged arm just as stiff as the good ones.  (I have 214 flights and 34hrs airtime on my Phantom 3)
2015-9-28
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mvgossman
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jaronpv@hotmail Posted at 2015-9-28 11:22
No flaw in the backpack.  The lip that the standard strong arm kit has can keep the backpack from  ...

This is odd because my hardshell backpack doesn't look all that tight and the strong arm attachment looks fairly small. Mine has the foam interior, perhaps there's a model that is hard plastic inside that is less forgiving? Mine is this one:

http://amzn.com/B011T7LWQS

I'll ask the support people about the reinforcing "strong arm" and this backpack. Incidentally, I don't really recommend the case, you have to remove the props to put it inside. This makes it more compact but the fewer times I gave to remove the props the better, and it takes a little time.
2015-9-28
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CFM01
lvl.3

United Kingdom
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I have no cracks - 10 flights and about 2hrs 20mins in time.
The 3D printer ones look good but only half way through building it.
So do I go for the other ones or not? I assume they are very easy to install?
2015-9-28
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jaronpv
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mvgossman Posted at 2015-9-28 12:39
This is odd because my hardshell backpack doesn't look all that tight and the strong arm attachmen ...

If you think the standard ones would fit, go for it!  I have those ones, and I love them.  I can feel the arms are stiffer when i compare the flex with and without the kit installed.  
2015-9-28
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jaronpv
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CFM01 Posted at 2015-9-28 12:57
I have no cracks - 10 flights and about 2hrs 20mins in time.
The 3D printer ones look good but only  ...

No cracks... Glad to hear it!  I would get them anyways.  to keep cracks from forming.   cheap insurance I would say.  And yes, the install is very very easy.  They recommend checking tightness of the bolts ever 10 flights or so.  I marked all of mine with a permanent marker so that one edge of each bolt has a line that points towards the center of the bird.  This way I can visually look and make sure no bolts have backed off.  
2015-9-28
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jaronpv
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skadar Posted at 2015-9-10 09:09
Dang, this kills me.  For the past week I've been struggling to pull the trigger on a $2000 P3 pac ...

Dont let it kill you.  Buy the bird.  Check it regularly.  Install the strong arm kit from UAVbits.net, and fly the bird.  I have 150 flights on mine.   Rear arms have a stress crack in the recessed hole for the bolt.  only two spots.  Have flown with the strong arm kit for 75+ flights.  no issues.  bird is strong as ever.  I would buy one again and again with the awesome time I have had flying! not to mention the awesome scenery I have enjoyed.
2015-9-28
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kjneblett
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Flight distance : 34016 ft
United States
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Has anyone who has installed the strong arm kit from uavbits had the stress cracks happen to them after?
2015-9-29
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