Hello
I've been able to duplicate this.
(M10, Macbook 10.9.4, 16GB. M10 is using the the higher performance of the two graphics cards NVIDIA GeForce GT 750M 2048 MB).
The kernel is quiting and leaving no messages as to why, and did not write anything to the system log.
The kernel crashes upon evaluation (not during writing the .stl), but did so only after several evaluations.
From a fresh kernel and after evaluating your code:
Do[Print[i]; Print[Timing[tmp = CurveA[i];]], {i, 1, 50}]
The kernel died at the 12th iteration, and then again at the 3rd iteration. So, it appears to be random.
This code is not using very much memory.
tmp = CurveA[18]
N@ByteCount@tmp
indicates that the result is only about 6MB (I am not seeing much of a spike in memory during the computation). The resulting .stl is also only about 6MB.
You can reduce memory usage during a Mathematica session by setting
$HistoryLength = 0 (*or some small positive integer*)
However, I don't think it will help in this particular case.
I'm guessing that this behavior indicates a bug.