Does anyone know how the math works out now for constructing? I tried the formula Bishop posted, but it didn't work out that way.
I tried to const a TL70 Const-mission with Dex 22, Int 25 and Cst 100.
According to the formula 22*0,1 + 25*0,2 + 100*0,7 = 77,2 I should be able to const it without failing. But I did.

So, is the "rule": skill should be 2 times the tech level of the item still the best way to avoid getting failures?