I think I've realized that the greatest risk of damage to the Crazyflie in a crash is that contact between the edges of the pcb and motor cans. After many crashes and manual deformations to try to remove dents, I've had to replace 2 motors from that so far. Those repairs put the main board at risk given the soldering operation that is now required.
Even with Paulo's great 3d printed frames, the force of an impact in the X-Y plane is still transferred to the motors which will propagate through that same point of contact. Over many such collisions, damage to that thin metal can seems inevitable.
Some kind of damper is needed there. I find no "stop" separating the pcb and motor and feel the gap in the plastic would have to be filled in, making it necessary to route the motor leads differently. In bigger quads such forces are much better distributed.
I notice that the way the pcb and motor mount slide on each other is similar to the inner and outer parts of a hydraulic cylinder. Given the shape of the motor mounts and pcb at the end nearer the circuitry, I was wondering if anyone considered springs around each arm of the pcb to keep the two parts separated.
In a crash, the motor mount would slide down the arm a bit, encounter the spring, anr transfer energy to the rest of the assembly. Naturally this would have to be a short, stiff spring, maybe slightly conical to distibute load to the pcb.
Just a thought!
Rich
Suggestion regards motor dents
Suggestion regards motor dents
VGer's v1.7.1 frame, 10DOF Crazyflie, Wireless Xbox360 Controller, Virtual Machine on VMware/Windows 7
Re: Suggestion regards motor dents
We really appriciate you input Rich!
The motor mount is accually not working completely as designed. There is supposed to be a bit of plastic between the motor and the PCB arm but the tollerances of the mould was to big and the cylider part of the motor mount ended up a bit tight. This makes the cylinder expand a bit too much so the PCB arm can reach the motor. Changing the mould to fix this doesn't seem doable either
. The best workaround right now is to put something between the PCB arm and the motor or to glue it in place, with a little hit glue maybe (or not to crash 
).
Other ideas?
The motor mount is accually not working completely as designed. There is supposed to be a bit of plastic between the motor and the PCB arm but the tollerances of the mould was to big and the cylider part of the motor mount ended up a bit tight. This makes the cylinder expand a bit too much so the PCB arm can reach the motor. Changing the mould to fix this doesn't seem doable either
. The best workaround right now is to put something between the PCB arm and the motor or to glue it in place, with a little hit glue maybe (or not to crash ).Other ideas?
Re: Suggestion regards motor dents
As said here my solution is a comination of nerf darts and what tobias said.
1. Make sure before you start (and after each crash!!!) that the word "crazyflie" on each arm is fully readable and preferable also the first mark on the arm is visible. This gives the arm always a bit of room to slide into the arm in case of a crash, which absorbs the energy by friction. This protects the motor and also the electronics, especially the accelerometer with lower jerks and shocks.
2. Push some foam between the arm and the motor-mount (e.g. nerf dart foam).. this works like a airbag.
Works realy great (so far) for me.
1. Make sure before you start (and after each crash!!!) that the word "crazyflie" on each arm is fully readable and preferable also the first mark on the arm is visible. This gives the arm always a bit of room to slide into the arm in case of a crash, which absorbs the energy by friction. This protects the motor and also the electronics, especially the accelerometer with lower jerks and shocks.
2. Push some foam between the arm and the motor-mount (e.g. nerf dart foam).. this works like a airbag.
Works realy great (so far) for me.