jonwvara 

I'm building a four-cross wheel and am having a lot of problems with breaking spoke nipples--in building two wheels I have probably broken 12 or 15 nipples. They don't actually break, but the threads strip out with a loud pop at what seems to me a pretty moderate amount of tension--less than what you'd expect in a finished wheel. I've been bringing the tension up gradually around the wheel a half-turn per spoke at a time, maintaining true as I go. BANG! There goes a spoke. A few spokes further, BANG! there goes another one.
I'm starting to think that the tension is actually too high. I don't have a tensionometer, so I'm guessing on tension by the sound the spokes make when plucked. They don't sound fully tensioned to me, compared to the sound of another (presumably properly tensioned) wheel. It occurs to me, though, that this comparison wheel is spoked three-cross, so it obviously has shorter spokes. This would perhaps make the spokes give off a higher tone when plucked for a given tension? So maybe I'm tensioning the longer spokes much more than I mean to judging by sound. It's also possible, I guess, that I have a bad batch of nipples, but that seems much less likely. They're new DT Swiss nipples and spokes. I haven't broken any spokes--just the nipples.