Stress Cracks

[KachemakDiver]

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[italiandrone]

This is exactly what I would have said. Shortly, it doesn't matter too much. Of course if you think they are getting worse or risky , best option is to replace shell or fix with epoxid. For your convenience, keep in mind that stress cracks are often due to "over tightned" or too long screws. Strange but true, the engineering of these almost-perfect phantoms fails because of the using of those ultra tightned and too-big screws. But don't worry too much!

I have a couple Phantoms. My Phantom 3 Pro has had stress cracks for over a year now and I fly it regularly haven't had any issues with it. There's a couple ways you could fix this. I'm not saying this is how you have to do it but this is just what I done. First I bought some covers for it. They sell machined aluminum covers that go on like the bottom the replaced with the factory screws underneath the plastic. Just recently I took those off and I used plastic epoxy( made by jb- weld) on all four arms underneath where the motors are and basically it put a protective layer of plastic coating and it seems to work Flawless and I have absolutely no issues. When I get home later I'll try to upload some pictures. Obviously if the cracks get too bad you may want to think about getting the new plastic for your drone top and bottom. My P3 Pro is my backup drone but like I said I fly it a lot and it's no big deal. Unless like I said they're really really bad.

 

[dronesky]

Hi all,
I have been using the cnc aluminum mount plates on every Phantom 3 I own for quite some time now. I put them on whether there are stress cracks or not. The ones that have cracks are not getting any worse. The ones that are crack free, are still crack free. I have flown them with and without the plates attached. In my humble opinion, there is no affect in performance by having them on. I personally like the look of them,, and they are a lot easier to install than replacing a new shell, and less money also. And, after you have replaced the shell, you eventually have another phantom with stress cracks! My opinion.

You make a couple good points the plates are cheaper and easier than replacing shell and new shell can crack to so could be a never ending cycle

 

[italiandrone]

A new shell WILL CRACKS. it's simply a matter of time.

You make a couple good points the plates are cheaper and easier than replacing shell and new shell can crack to so could be a never ending cycle

 

[italiandrone]

These small cracks AREN'T risky...imho.
You can fly decades. I wd not replace the shell until they get worse.

Right on. Appreciate the knowledge. Pretty much what i figured. Amd if your out there flying in alaska lol they must be up to the challenge.. the new shell is already shipped unfortunately. And i want to replace it anyway. The landing gear are bent too and think the whole shell is a little out of whack so ill def add the motor mounts for sure either when i replace it or a few days after as soon as i can muster up the cash just bought all these little goodies to go with the new shell heres my cracks.. i put a little jb plastic weld to hold her for a couple days until the new shell.comes

 

[PhoenixOne]

These small cracks AREN'T risky...imho.
You can fly decades. I wd not replace the shell until they get worse.

You don't think so? Im no expert for sure but you don't know what this bird means to me.. lol I can't lose it. I only paid 20 bucks for the whole shell and landing gear. So i dont feel like im losing much. I also dont want to lose my new cf props or anything else i upgraded.. The reason i want to change it is for looks number one. I be using it for a part 107 until i upgrade to a newer drone. I dont want her looking all glued together..Number 2. When the drone is hovering eye level you can see one of the props i believe the front left is misaligned with the back prop so the tips arent level. So it seems one motor or mount or the shell is bent. Something is causing one prop to look off kilter a bit... could be a bent prop but dont think so because that would more than likely cause vibration issues. Ill have to check the alignment with the new props.

 

[Shoot4fun]

The cnc bolster plates are effective for preventing cracks, as well as for keeping already cracked housings together. My second P3s came with them installed although there were no cracks, and I immediately purchased a set for P3s #1, which had one small hairline crack forming under one motor. The latest purchase, a P4pro, will also be getting some type of reinforcement plates as well. It's very cheap insurance.

 

[Shoot4fun]

Awesome yeah ive had quite a few smaller ones apart and have some build experience with soldering skills so I think ill be alright if intake my time like you said. Thanks for the support. And now the question is to paint the shell before i put it on?? I have a good flat black thats chip resistant. Uv fade resistant and industrial strength. Ive ised it on my grill and bumber for my truck.. turned out amazing. And never a rock chip. The added weight of a couple coats shouldn't bother the bird to much I wouldn't think. Im very ocd so it will hopefully come out looking pretty decent. Or should I go with the flat olive green or miltary green? Choices

That's a personal preference, my man! Mine is getting a new skin upgrade shortly...

 

[cheddarman]

Cheddar man whats your opinion on dji brand carbon fiber props? I did a quick test flight a quick hover and throttle punch and they dont seem to be out of balance much if at all but I'm no expert. Should i buy a balancer and balance them properly? Or assume they are somewhere near the right tolerance and keep flying. I noticed one stress crack i didnt see before after the flight but its a good possibility it was there before hand. After i put the new shell on in a couple days I want to make sure she is in top shape flying the best she can be. Thanks for any input

I've never used anything but the white plastic props. All props should be balanced as received but I always check mine.
Start the motors and feel (pick it up by the legs) and see if you feel any obvious vibration, put a finger tip against the side of each motor.
Accelerate the motors (be careful needless to say) and see if you again feel any vibration.
All rotating masses have a "critical speed". This is when the rotational speed equals the resonant frequency of the rotating object. At this speed all rotating mass will exhibit vibration. I would think that the resonant frequency of these props is well above its operating speed (it's called a rigid rotor) so you shouldn't get any noticeable change in vibration when accelerating.
I use a TRU-SPIN PRO BALANCER and have made a steel shaft which is a snug fit into the propeller locating hole as the props do not have a hole right through them. Works well.

 

[PhoenixOne]

I've never used anything but the white plastic props. All props should be balanced as received but I always check mine.
Start the motors and feel (pick it up by the legs) and see if you feel any obvious vibration, put a finger tip against the side of each motor.
Accelerate the motors (be careful needless to say) and see if you again feel any vibration.
All rotating masses have a "critical speed". This is when the rotational speed equals the resonant frequency of the rotating object. At this speed all rotating mass will exhibit vibration. I would think that the resonant frequency of these props is well above its operating speed (it's called a rigid rotor) so you shouldn't get any noticeable change in vibration when accelerating.
I use a TRU-SPIN PRO BALANCER and have made a steel shaft which is a snug fit into the propeller locating hole as the props do not have a hole right through them. Works well.

Thanks cheddarman! You know your stuff for sure. I kinda thought the same thing. ill get a balancer shortly and try the motor touch first as risky as it sounds lol. I like the risk! Jk! are you into other aviation as well or just a drone pilot? Seems like your very knowledgeable.

 

[PhoenixOne]

That's a personal preference, my man! Mine is getting a new skin upgrade shortly...

Sweet skin. Yeah i was thinking of getting one instead but i know ill fail horribly when I try to put it on. I like the paint idea cause i can cover everything but the camera and motors. I even have access to real automotive paint and was gonna go with a crazy color or some pearl white. But i wondered if primer base and clear would add more weight than i want. I know that seems like a small addition but I'm trying to stay in the air as long as possible. I like the black cause it comes in spray can and is only 5 bucks and its strong and coats so easy and comes out smooth and chip resistant and industrial strong might add a little rigidity to the shell. I talk too much.. haha

 

[Capt KO]

Are the CNC cut shells the ones with the longer screws that kill the motors? Read about that problem somewhere that short screws are needed.

 

[PhoenixOne]

Are the CNC cut shells the ones with the longer screws that kill the motors? Read about that problem somewhere that short screws are needed.

Yeah I heard somebody say that too. And thats what weve been talking about yes Though they claim the cnc mounts help with heat sink. If you had the right screws you could.
make the plates out of alot of material. 3d printer or laser engraver which i have..

 

[Deleted member 120647]

With regard to bolt on reinforcing has any one also glued the reinforcing to the shell?

 

[PhoenixOne]

With regard to bolt on reinforcing has any one also glued the reinforcing to the shell?

With only glue or screws and the glue one of the guys said he used some JB Weld or plastic Weld between the mounts which is what I have on my stress cracks and only that. That's a good question though I wonder if only glue would eventually break or shake loose it would have to be some really strong glue

 

[dronesky]

The longer screws are to be used with propeller guards & reinforcement plates only if you take them off Don't use the screws when tightened down without guards/plates the screw goes into the windings of the motor destroying the motor

 

[Deleted member 120647]

"That's a good question though I wonder if only glue would eventually break or shake loose it would have to be some really strong glue"
I was thinking more along the lines of screws and a semi flexible glue or, having seen the seemingly double sided sticking tape DJI use to stick down rbbon cables extending that idea to double sided tape

One thing about the reinforcements I have had alook at is that they appear to change the way the motor mounts are clamped to the shell. Originally it is the 'drilled' disc of material at the end of the screw hole that is clamped between the bolt head and the motor mount. With reinforcement plates it looks to me as if it is the walls of those screw hole recesses that are 'squashed' onto the above disc. I wonder if the change has any significant effect.

 

[PhoenixOne]

H

"That's a good question though I wonder if only glue would eventually break or shake loose it would have to be some really strong glue"
I was thinking more along the lines of screws and a semi flexible glue or, having seen the seemingly double sided sticking tape DJI use to stick down rbbon cables extending that idea to double sided tape

One thing about the reinforcements I have had alook at is that they appear to change the way the motor mounts are clamped to the shell. Originally it is the 'drilled' disc of material at the end of the screw hole that is clamped between the bolt head and the motor mount. With reinforcement plates it looks to me as if it is the walls of those screw hole recesses that are 'squashed' onto the above disc. I wonder if the change has any significant effect.
[/QUOTE Hhmm. Thats interesting. I agree with maybe a light soft glue but the double sided tape might add too much squishy between the two surfaces and nullify its effects? Possibly. And yeah idk but that sounds kinda sketchy if it messes or alters the way the motors go in or the shell aligns or weakens the integrity anywhere else i might just pass and make sure I don't over tighten my screws and maybe a little loctite to make sure they dont back out from being lightly turned. I notice replacing my yaw arm that over tightening any screw on a dji will more than likely have adverse effects or is it affects? Doh..

 

[dronesky]

Please do!! I have a 3d printer. And a laser i could cut something similar out of a different material if i could find the design online. But im hesitant because i dont want to use too weak of a material or use a design that could possibly add more stress to the shell. Cause they are rounded and curved a bit. Or if i should just let it ride with the new shell cause well its a new shell. Just maybe dont over tighten anything?

Got the plates put one on my only cracked arm motor spun free thought I'd power up see if there was any problems & the motor with plate just twitchs without spinning at this point I'm worried my motor has been damaged so took plate off put old screws back in & tried it again ? it works with no apparent damage so guess will try the gluing method and keep track of the cracks don't really want to replace shell afraid it wont fly like it does now it's the best flyer i've had

 

[PhoenixOne]

Got the plates put one on my only cracked arm motor spun free thought I'd power up see if there was any problems & the motor with plate just twitchs without spinning at this point I'm worried my motor has been damaged so took plate off put old screws back in & tried it again ? it works with no apparent damage so guess will try the gluing method and keep track of the cracks don't really want to replace shell afraid it wont fly like it does now it's the best flyer i've had

Man thats crazy! Thats no good! We definitely need to figure out a different solution. My new shell came today and I have some interesting news it seems to have the lines right were the cracks would form. Like light scratches it looks like from the molding process or something. Almost like predetermined cracks like im scared to put this thing on and now im scared to order the motor mount plates... what to do. They might be nothing . Sorry they messed your motor up even for a second. I know that is stressful. Which brings me to this question if your flying part 107. And you know your craft has stress cracks and do a preflight check are you in the wrong if you let it fly with stress cracks? Or only wrong if something unfortunate happens? Or are you guilty just putting it in the air? Heres the pics btw