Great that it is holding up!
One thought is to design a 3D printable part that would strengthen the arm or could be used to repair it. The Shapeways strong and flexible material is pretty good as we used it for our previous motor mounts.
The current arms are pretty strong and elastic which protects the sensors for high g force as well as the soldering. Making it to stiff and we will just move the problem else where. That's why making the motor mount the weak part I think is the way to go. It could be as simple as cutting the PCB arms 10mm shorter and having the motor mount hanging a bit. Another idea to make it stronger is to tie a fishing line between the arms. That would make the construction strong, flexible and light.
As soon as I have time a will do some experimenting. I have some old prototypes I can use as crash dummies.
san84 wrote:I managed to repair the arm. I did some careful flights with some small crashes and it holds. I still have to see if it also holds in a bigger crash. I used "Bison Kombi Snel" a 2 component epoxy glue and aluminium household foil. I cut a strip of foil and applied glue to the not shiny side and wrapped it as tight as possible around the fracture to strengthen it. I had to shorten the motor mount and glue it because it was not really press fit anymore.
Fixed arm.jpg
What are you using on your motors as shock absorber? The purple things? Thanks!
The purple things I use as shock absorbers I salvaged a long time ago from a broken CD-ROM player. They are hollow and there is a hole in the middle where a screw went through. In the CD-ROM player it was also some kind of shock/vibration absorber. They work great but sometimes my Crazyflie will bounce up and land on it's back.
I just quickly wanted to explain my theory. Still a lot of testing left to be done. The pictures should be pretty self explanatory but the idea is to make the motor mount the weak/flexible part by moving the motor mount out a bit.
Attachments
Motor mount flex up.png (377.78 KiB) Viewed 10438 times
Motor mount flex side.png (314.49 KiB) Viewed 10438 times
Motor mount flex down.png (376.6 KiB) Viewed 10438 times
Motor mount flex attachment.png (326.01 KiB) Viewed 10438 times
Hmmm. Interesting idea Tobias. One could then wrap that arm end with the fishing line, you mentioned above, to strengthen the member so that the flex is not too soft. The combination of flexible motor mount and wrapped fishing line would add dampening from vibrations and absorb the shock on impacts.
mine broke also the second flight test exactly the same spot. all in all this is clearly the weakest spot. actually i exepected a better product and honestly i would not buy it, if i knew. and support from bitcraze to fix this or provide a solution is inexistent. also refund does not seem to be an option. so, actually i dont recommend buying a crazyflie at current state, as its simply not worth the money.
toastbrot wrote:and support from bitcraze to fix this or provide a solution is inexistent.
I wont bite to the rest of the trolly stuff in your post but I wouldn't say that it's inexistent. This was linked in the post above yours and there's some other stuff in this thread aswell.
