This is only the second time I’ve built a set from scratch…
Multiple calculators come up with lengths as 294.1, 295.1, 294.2, 291.6
So, 294s and 292s ok? 12mm Brass nipples.
Ta! 🙂

I’d rather have 296 for the 295.1 than 294 personally but I get that ideal length may not be available.

The substitution you’ve given will work, but you’ll not have as strong a wheel, the 294 in place of 295.1’s will be weaker at the spoke:nipple joint due to poor insertion depth.

In practice you may never notice the difference, will depend on how well tensioned the build is and how hard the wheel is ridden…

The nipple head is approximately 2mm deep and would take about 5 turns to traverse (56tpi). Assuming the calculator aims to leave the nipple flush with the slot, 1mm short is still fairly well engaged in the head portion of the nipple imho. You’re in the zone of uncertainty though. If ERD is slightly off or some other assumption of the calculator is violated then maybe you will end up closer to the “no-go” pictured below than you’d like. I’ve used about 1mm short because it allowed me to get away with using the same length on each side.

Any more than 1mm short starts to run the risk of the nipple head cracking off because it is left unsupported. There are some great photos which illustrate this in cross section.

A good alternative is to use the longer spokes with nipple washers.