Crack Repair Kit On Amazon

most cracks Ive seen appear on top, so I doubt these would help at all. And yeah, they will reduce flight time, though likely hardly noticeable.
 
most cracks Ive seen appear on top, so I doubt these would help at all. And yeah, they will reduce flight time, though likely hardly noticeable.

I think what it's doing is adding a thin metal plate below the arm attached right to the rotor. Basically it's making the plastic area holding the rotor no longer load bearing.

Since I'm out of warranty, this seems like a much more economical way to do this repair instead of sending it to DJI.


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The only problem with the product shown by the original poster is that reinforcement plate if flat. You REALLY want the ones that have the built-in inserts, see below.
They will fit better and provide more strength. It is IMPORTANT to not over-tighten any of these screws.The longer two (not the motor mounts) are going into a molded-in threaded insert that will break loose from the plastic if any force is put on them.

upload_2016-8-22_18-47-8.png
 
The only problem with the product shown by the original poster is that reinforcement plate if flat. You REALLY want the ones that have the built-in inserts, see below.
They will fit better and provide more strength. It is IMPORTANT to not over-tighten any of these screws.The longer two (not the motor mounts) are going into a molded-in threaded insert that will break loose from the plastic if any force is put on them.

View attachment 62899
Where does one get these plates? Pretty slick
 
The only problem with the product shown by the original poster is that reinforcement plate if flat. You REALLY want the ones that have the built-in inserts, see below.
They will fit better and provide more strength. It is IMPORTANT to not over-tighten any of these screws.The longer two (not the motor mounts) are going into a molded-in threaded insert that will break loose from the plastic if any force is put on them.

View attachment 62899
The ones the OP posted have the standoffs. The picture you posted has them sitting over the holes. Look at his link again and you will see the posts next to the screws. It also uses countersunk screws. The idea is to take the pressure off of the screws on the plastic and have the screws holding the metal to the plastic.
 
Initially there were tons of complaints for cracks, DJI started replacing free, they also controlled shell material and forming process. On the other side people started using strengthening plates. Crack complaints drastically reduced on forums.

What actually finally reduced the complaints is not known but it's true strengthening plates will reduce chances of developing cracks.


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This is what reduced my cracks!!! After 8 shell replacements!!
 

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The ones the OP posted have the standoffs. The picture you posted has them sitting over the holes. Look at his link again and you will see the posts next to the screws. It also uses countersunk screws. The idea is to take the pressure off of the screws on the plastic and have the screws holding the metal to the plastic.


Nope, you're totally mistaken. The OP has a FLAT mounting surface where the motor screws are and SEPARATE BUSHINGS for the other 2 mounting holes. The units I endorsed have integrated sleeves on ALL 6 MOUNTING HOLES. There's a huge difference, look again.

Without the integrated sleeves they can neither fit as well nor disburse load as well.
 
The strong arms don't work!!I still got cracks I have used carbon fibre and the alloy...still cracks on my shell!!! Got rid of them!!

They pretty much cant work. They may "work" if the root cause is over tightening the bolts, but in all other cases, its the weight of the quad that is being pulled by the motors. Imagine the shell was made of soft rubber, now lift it by the motors, and you can imagine where it will bend first: there where its thinnest.

You can add steel reinforced concrete blocks under the motors if you want, but those arms are still going to need to cope with the weight and vibrations of the quad and those reinforcements will do absolutely nothing IMO. You'd probably get better results from tying some kevlar wire around the arms, and then cross them below the frame and tighten the wires.
 
My experience is very positive for supporting plates under motors.
I ordered the quick connect prop guards the same time as I got my p3a and installed the mounts before my first flight. What I noticed was how thin the wall is where the original screws seat in the plastic. What the blocks did for me was give that seating area a much thicker base and move the pressure evenly around the back while totally removing it from the original plastic countersunk areas.
After a year and a half of many flights l have zero stress cracks. This is the reason I left the mounts on even though I'm rarely using the guards. I'm not sure if this will help much with previously cracked arms but goes a long way in keeping the motors in place if things go bad.
I like both designs that are on this thread but since I'm a machinist by trade I prefer the CNC machined ones rather than the cast ones.
They look very professional.



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Nope, you're totally mistaken. The OP has a FLAT mounting surface where the motor screws are and SEPARATE BUSHINGS for the other 2 mounting holes. The units I endorsed have integrated sleeves on ALL 6 MOUNTING HOLES. There's a huge difference, look again.

Without the integrated sleeves they can neither fit as well nor disburse load as well.
Those other stand offs make no difference as the plates rest flush against the arm at those points, the sleeves on those four holes do not rest on anything, they just slightly go into the screw holes. They do nothing. The reason for the rear standoffs is because the arm bends at that point and the plates are not flush. These stand offs rest in the screw holes of the same plastic that cracks. So there is no strength gain there either....but think what you want. Users of these plates still get cracks. The plastic is brittle, being in the sun probably accelerates the break down, plates or not.
 

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