Unexplained broken folding arm Mini 2

[mpa]

Hi all
so my folding arm on my mini2 has broken. has this happened to anyone before?
I only had a total of 2 hours flight time from brand new, Ive had it in storage for a about 18 months and opened it up to find it like this as i folded it out.
ive owned a mavic pro before for years so i have a bit of flight time under my belt and Im pretty certain i haven't hit anything,
im just wondering if this is just a weakness in the design?
keen to hear if anyone else has had this problem.

 

[slup]

That damage isn't just something happening while stored, pieces are missing... that's coming from some kind of rough handling (not necessarily from you or intentionally).

 

[mpa]

That damage isn't just something happening while stored, pieces are missing... that's coming from some kind of rough handling (not necessarily from you or intentionally).

the pieces are still there just not in the photo, it fell out as i opened it up.
im thinking the spring mechanism pushing on the plastics over time weakening the frame maybe?

 

[Cafguy]

How many guilty looking Family members do you have living with you! I agree with Slup. unless you stored it somewhere the area fluctuates wildly between extreme heat and cold. then Maybe- But I think somebody Messed with it and Broke the arm.

 

[Yorkshire_Pud]

My guess would be that the one way that could done is if the pivot seized and the arm was the forcibly rotated but something has exerted a lot of force to do that and no I haven't seen anything like that before.
But even then, the alignment of the base plate relative to the arm is not quite correct for the pivot to be in the storage position.
I would see if you can twist the pivot base relative to the arm.
The Mavic Mini is designed in the same way and my most used Mavic Mini has a LOT of arm foldings and unfoldings under its belt and there is no sign of anything like that happening.
It's coming up on DAT number 1,000 so at a guess probably at least 700 unfoldings.
The drone needs a new middle and top shell and possible pivot and arm but if you are handy and can solder its a fairly simple dimantling and rebuild. The trickiest bit is peeling the gimbal ribbon cable and its extensions off the old shell ( heat might help ) and then lining it / them up in the new shell.

When opening and closing the arms control their swing the whole way through their travel, don't let them spring open or shut against their stops.

 

[msinger]

Ive had it in storage for a about 18 months

Where was it stored?

 

[mpa]

Where was it stored?

in a locked filing cabinet, in the flymore carry bag

 

[msinger]

What's the environment like where the filing cabinet is located?

 

[mpa]

What's the environment like where the filing cabinet is located?

not overly too exciting, its my home office, it gets to 38 maybe 40 some days can get to as low as 10 degrees C.

 

[msinger]

Storing drone equipment (especially batteries) inside of a filing cabinet at 40 C (104 F) is not ideal. However, I'm sure you're not the first person to have done something like that. I've never seen anyone post damage like this from a drone that was in storage.

The plastic on Mini models (especially the Mini 1 and Mini 2) is definitely more brittle/lightweight than other DJI drone models. And with the stress that is placed on that section of the arms, that would be a likely location for cracks to appear if the plastic was somehow compromised by the environment.

This reminds me of the cracks that commonly appear in the thin plastic top of Phantom 4 batteries:

 

[mpa]

Storing drone equipment (especially batteries) inside of a filing cabinet at 40 C (104 F) is not ideal. However, I'm sure you're not the first person to have done something like that. I've never seen anyone post damage like this from a drone that was in storage.

The plastic on Mini models (especially the Mini 1 and Mini 2) is definitely more brittle/lightweight than other DJI drone models. And with the stress that is placed on that section of the arms, that would be a likely location for cracks to appear if the plastic was somehow compromised by the environment.

This reminds me of the cracks that commonly appear in the thin plastic top of Phantom 4 batteries:

View attachment 172040

i think you would be pleased to know the 3 batteries were stored elsewhere, along with my other lipos

 

[mpa]

My guess would be that the one way that could done is if the pivot seized and the arm was the forcibly rotated but something has exerted a lot of force to do that and no I haven't seen anything like that before.
But even then, the alignment of the base plate relative to the arm is not quite correct for the pivot to be in the storage position.
I would see if you can twist the pivot base relative to the arm.
The Mavic Mini is designed in the same way and my most used Mavic Mini has a LOT of arm foldings and unfoldings under its belt and there is no sign of anything like that happening.
It's coming up on DAT number 1,000 so at a guess probably at least 700 unfoldings.
The drone needs a new middle and top shell and possible pivot and arm but if you are handy and can solder its a fairly simple dimantling and rebuild. The trickiest bit is peeling the gimbal ribbon cable and its extensions off the old shell ( heat might help ) and then lining it / them up in the new shell.

When opening and closing the arms control their swing the whole way through their travel, don't let them spring open or shut against their stops.

Thanks mate, already have the top and mid shell on order, do you know of any good guide to get this job done?

 

[Starz]

Information.

 

[Yorkshire_Pud]

I don't remember the one I used sorry but it was almost certainly a youtube video, try a google for mini 2 and teardown or dismantle and watch several videos, NOT just one. Some are by hamfisted folk who shouldn't be allowed near a bull dozer.

Tips,
1) heat is likely to be your friend when dealing with CAREFULLY peeling ribbon cables off the old drone AND removing blobs of glue that DJI use in various places.
2) PHOTOgraph cable routings and soldered connections so that you have a record of how and where things go.
3) The front arm pivots can be awkward beep beeps. Removal, slowly open the good arm until it reaches the tipping point between spring open and spring closed, leave the arm in that position and then remove the pivot, this removes the torque that the pivot would exert in anyother position and makes the pivot removal and especially the refitting much easier. See How to swap engine/motor on rear arms?
4) patience is a virtue, if you find yourself getting annoyed put the drone down and go and have a cup of tea or something.
5) depending on your eyes a head mounted magnifier with built in lighting might be a good idea.

 

[Crash Gibby]

Information.

I know if mine breaks it will go to the recycle bin. Way too many parts for me to fix. Great video thou. Thanks for posting it.

 

[Starz]

go to the recycle bin

AKA eBay. Thats where a lot of crash parts end up.

 

[mpa]

Thanks everyone for your replies,

Heres an update, ive ordered genuine replacement top cover and mid body for around 60 Australian Rubles. Ive manage to disassemble the entire drone (which I vowel not do to ever again because it’s a pain!) and started to populate the new frame. While disassembling the old frame the other front arm crumbled in the same way and throughout the disassembly there were bits a pieces breaking off.
my conclusion so far
I think to make the drone 249g, DJI put the mini on an extreme diet so there are bits of the frame that are super thin, the plastics appear to age very quicky and therefore breaking prematurely ( the type of breakdown in the plastics reminds me of car keys that crumble after about 10 years). The folding mechanism requires a considerable amount of force to reposition during reassembly and the constant force particularly higher torque load on such a tiny footprint on the mount bracket is probably what is causing the plastic to break over time in my case.

 

[Yorkshire_Pud]

The folding mechanism requires a considerable amount of force to reposition during reassembly

Did you read post 14, in particular point 3) and the accompanying link ?

and the constant force particularly higher torque load on such a tiny footprint on the mount bracket

My most used Mavic Mini is coming up on DAT number 800, my most used Mini 2 is coming up on DAT number 300, both those numbers are accurate as I activated both drones.
With my usage that means that the arms have been opened nearly as many times as the DAT number plus a similar number of closings.
I have not noticed any problems with either drone.
My third Mini 2 is a complete rebuild into a second hand frame and its DAT number is at least 178, given that my records start at DAT 25 for that drone then I have probably opened its arms in excess of 140 times and I have no idea how many times the replacement shell had been used before it was stripped for parts.

Honestly I think that something 'odd' has happened to your drone.
Maybe the spring strength in the pivot was greatly increased at some point and I have weaker springs, or, is there any possibility the shell has been exposed to chemicals or chemical vapour or, when opening and closing the arms, do/did you allow the arms to snap open and closed ?

Anyway, congratulations on the rebuild.