I have designed and built custom carbon fiber frame. The frame is composed of flat carbon fiber sheets and rolled car and fiber tubeds. Tubes are used to support A frame and dampen vibration. The tubes are joined Via high strength Apoxsee and are are threaded with Metal bolts. When I arm the motors I noticed that the bolts that are running through the carbon fiber tubes our heating up but the bolts are not touching any exposed conductive electrical wires. When I take my multimeter and touch a lead to one bolt that is running through the Carbon fiber tubes and the other lead to another bolt connected to the carbon fiber frame I am getting Conductivity to ground. Yet, again, the bolts are not touching any exposed wires.
Is conductivity through carbon fiber normal? I am concerned that this can produce a short Circuit.
Yes, carbon is very conducive
OK. So I guess the whole frame should be wired the ground?
I don’t use the frame as a ground conductor but you need to keep in mind that it is conductive and never let non-ground level conductors come in contact with it.
I must have a non-ground conductor that is in contact with my frame. I have a couple of metal bolts that are going through the frame that are not touching any wires whatsoever but yet they are getting hot to touch when the motors are armed. Also I am getting a burning odor but I can’t find out where it’s coming from. I am getting Continuity across the frame and have double checked that no wires are touching. This is driving me nuts.
Hi Mike,
Grounding everything in the frame is a good practice if you know what are you doing, it will help you shield a lot and all grounds will run smoothly.
By saying “Now what are you doing”, i mean that you took all measures for gorund loops, you measured possible ground planes for your antennas etc.
For your odor problem, the usual suspect are the motor mounting skrews, that poltrude the CF motor mount plate and slightly touch the rotor ac wires. even a single phase touching will make an arc and burn the CF hairs of the hole. beware that if thats the case then the arc could happen in a far away hole that has CF hairs to be burned and not nearby the problematic motor.
loose your motor screws one by one, arm and check
Well respected and understood.
Thank you very much. I will give it a try.
Mike