Some updates with 3.80:
Masterwork staff and 8 Decent staffs, got 5 Fine, 4 Decent and 1 Rough javelin.
The vanilla recipe uses COMMON with no skill modifier; so flat 50.
So there's been some rebalancing in last 3-4, 5? years.
With Carpentry 64-68, using Fine wood slats I get about 90% Fine arrows with Decent heads. Using Fine heads and Decent shafts I get about 75% Fine arrows. This character's Timbercraft is not high enough to produce Perfect boards. Using masterwork heads only yields Fine arrows, regardless if using Decent or Fine shafts. (that was expensive experimentation)
I think I need to wait for late winter, then go start a new cabin. Timbercraft should go up nicely. I'm sort of expecting to get Superior arrows with decent heads and Perfect arrow shafts. Carpentry might hit 70 over the winter, which can skew the testing results.
All arrows were tied with Fine linen yarn.
Might need another toon to test with. Higher Timbercraft, Carpentry in 40-50 range.
I have tried producing superior arrows with masterwork arrowheads, fine arrow shafts and fine yarn and i seem to be able to do so about 25% of the time