Hello,
do you have any proven companies that are able to cut a carbon tube of the right length and drill holes in it with high precision on both sides of the tube like on picture below?
drilling holes drastically reduces carbon tube strength. why not use a clamp of some sort?
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Not necessarily in a way that matters, I have done break tests of CF tubes with holes drilled in neutral stress or compressive stress areas with no measurable difference. And holes at the end of the tube where there is likey a large clamp around the whole area are also unlikely to have a meaningful effect.
so stress concentration does not happen in carbon fiber tubes? surprising, especially since you break through lamination layers when drilling. do you have more details?
additionally using clamps can be more practical. only need bare carbon tube, is adjustable, and you dont need a special fabricator to drill the holes…
Below is the type of foldable drone arm mount that I will use. I want to drill holes for safety. The hole is outside the clamp area, which will in no way affect the strength of the tube.
oh, it has a clamp already. the hole is to resist twist. then that should not be a problem in terms of stress. wonder if the clamp is enough to resist twist though.
I once had a situation that the bolts from the clamp loosened in flight and the propeller turned slightly in relation to the plane of the drone. This time I would not like to risk.
fair enough. overstress is not the issue with your setup, just practicality (difficult to find someone to fabricate it accurately enough).
ive been planning on building lighter frames with carbon fiber tubes, joints are the main issue. i am thinking of printing circular clamps with a layer of rubber for extra grip.
It’s a good idea to paste about 1cm2 of double-sided tape into the clamp.
did you try that? does it still not prevent tilt?
Yes, it is working very well, but for my 12kg drone I need extra safety with screws in carbon tubes
well, if you dont end up finding anyone to do it you could use an aluminum square tube as a jig for drilling the holes. 3d print square tube shims if you cant find a square tube that matches the carbon tube dimensions.