Bigben2k, that base thickness is for waterblock with straight chanell design, and it doesn't aply for every design out, I can only say one thing did you ever look at innovatek wb, check it out and you'll see that you've got things wrong, btw it outperform prabably most blocks out there (comercial) except maybe some diy blocks.
#Rotor, there is no gap between the block and the cone, I was also thinking about making chanells a little spiral, but how on earth could I do that, for something like that I would need like 5 axis cnc mill
Jessfm, that block looks awesome too, great job m8