I got my Crazyflie yesterday evening and I really love it. However my flying skills are not that good and especially in the beginning resulting in a lot of crashes. Today I was getting the hang of it and became better and better in flying. Until I hit the ceiling and the Crazyflie fell down with one arm on the edge of the table. The arm didn't survive this crash and broke off. As you can see it snapped at the point where the motor mount begins.
Broken arm1.jpg (32.44 KiB) Viewed 8940 times
Tomorrow I will try to fix it with glue and maybe something around it. I will then probably need to shorten the motor mount otherwise it will not fit around the arm. I also ordered some carbon beams of which I am going to try to build some kind of replacement frame. Maybe cutting off all the arms to reduce weight and mounting the Crazyflie on top of the carbon frame. I have no idea if that is going to work and how to mount everything yet but I will find out when the carbon beams arrive. Someone any bright ideas? BTW I also ordered another Crazyflie.
As a side note: I also had the same problem as here that my motors would start to protrude at the bottom of the mount. I think the "stop" is a little bit too small.
Last edited by san84 on Tue May 14, 2013 7:32 pm, edited 1 time in total.
Ah man. bummer. Well now we can realize the good idea and decision they made to run the motor wires to the central board instead of having traces out along the tiny arms. heck we can break all 4 arms and still whip a quick lite sturdy frame together for the motors. a little hot glue would work in a pinch
Sorry to hear about the arm! One trick that we have used in the past is to drop by a hobby-shop (or RC-shop) and pick up either a circular pipe or a square pipe (they usually have really small dimensions) and cut it to a centimeter of length. Put the pipe half way onto the PCB part, put some glue in and then insert the wing part of the PCB. This way you will create a splint for the wing and it will hold better.
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.
skube wrote:The motor mounts seem to offer natural reinforcement but perhaps they can be extended in the next iteration (CFv2 ) to a wider position on the board.
That's a good idea. The problem might be that whatever method you use to repair the wing will probably make it a bit thicker, thus stopping the motor mount from being inserted completely.
I think ultimately we want the motor mount to break instead of the PCB arms and that is something we should investigate. It might be as simple as making the PCB arms a bit shorter and to only have the motor mount the last 10mm or so. That would bend the motor mount and hopefully not the PCB arm. The construction might not be rigid enough though and it will probably require the motor mount to be glued to stay in place.
Since I expect to be doing a lot of crashing once I have my CF, I plan on waiting with flying until I have some kind of protective frame. There are a few good ideas for 3D-printers (you've probable seen this one: http://www.thingiverse.com/thing:84169) but has anyone thought about strenghtening the arms using carbon fibre? Problem is ofcourse to get more advanced shapes which, such as the linked frame, is easier using 3D printing.
After a few days of flying (and crashing) my fix still holds. Tomorrow i can collect my package with carbon fiber rods at the post office but will not use them for the moment and keep my frame as it is. If I break one of the arms again I will decide what to do. I think that strengthening the arms itself with carbon fiber is not a good idea because it might increase the stresses on the main PCB and shift the weakest point to the main PCB. I'm not sure about this so I could be wrong. The thing I'm sure of is that the motor mounts will not fit anymore.
) to a wider position on the board.