What's causing this print defect?

[Geoff]

I was thinking about that too, but that wouldn't explain why there's that repetitive defect at the same area in multiple layers...

I have printed other parts with the same settings and different filaments, with similar results, and the same settings have also yielded perfect parts. I printed one other elongated part with silver and transparent red PLA, and those had almost identical defects at the same spots, but nothing severe like with that black part. Also some small cylindrical parts I printed today four at a time, resulted with one good part, and three little bit messed up parts. This is so weird...

I'm using Simplify3D, but I think I might give it a shot and try makerware or something to print some problematic piece, to see if it's hardware or software which is acting up...

I know it's a silly question, but this particular piece has been netfabbed yeah? if your STL has a hole, it will present that also if the slicing program fails to register it.