genuine question because i keep going back and forth on this. cracked an arm on my tpuframe last month, printed a replacement arm no problem. but now the main plate has a hairline crack running from one of the stack mount holes almost to the edge and im not sure if i trust it or not. its not fully through, i can barely feel it with my nail.

i know carbon fiber can delaminate weirdly and a crack that looks small can be structurally compromised way more than it looks. but also replacement main plates arent cheap and the rest of the build is solid. ive been flying it anyway if im being honest and it hasnt gotten worse in like 6 flights but i keep thinking about it

how do you guys make the call? is there some kind of rule of thumb or do you just eyeball it and hope

yeah dont fly that. i know that sounds harsh but a crack near a stack mount hole is basically a stress concentration point and carbon doesnt give you a lot of warning before it just goes. it wont slowly get worse and then fail gracefully, it'll be fine fine fine then suddenly your quad is in pieces mid-air. ive seen it happen. the plate is probably like 15-20 bucks to replace and its genuinely not worth the risk especially if youre flying anywhere near people or expensive stuff

tbh ive been in this exact situation and i just kept flying it for a while too so not judging lol. what i eventually did was put a tiny drop of thin CA glue into the crack, let it wick in, then hit it with accelerator. it wont make it stronger than new but it kind of stabilizes it and you can watch if it grows. that said the other reply isnt wrong, stack mount area is the worst place for a crack. if it was on a less critical part of the plate id say ride it out but there... id probably just order the replacement and use the cracked one for a static bench queen or parts donor