Originally Posted by
noglider
@
dabac, the top spoke in the picture shows an acceptable gap. The mistake is in making it so big that the top of the spoke doesn't reach the bulging part of the nipple.
1) in that case, you shouldn't have any objections to the OP using longer nipples to finish his build, assuming the math and measurements is correct. If the spoke calc is set for a spoke to end flush with a 12mm nipple, then doing that build with a 14 mm nipple and a 3 mm short spoke should leave you with sufficient engagement.
2) The thing is that the top spoke is bottoming out on the threads. It won't go any further in. And at that, the spoke is about three turns into the bulging part of the nipple. If you want to keep some margin for future tightening, three turns of engagement is a fairly small window to shoot for with spokes generally available in 2 mm interval.