I shoot carbon ex predator2 @29"(9.7gr) with 4"vanes
My broad heads are 100gr. I can add up to this point, but how much does the knock, and vanes add on to total my arrow weight?

Nocks usually weigh about 12 grains. Vanes can vary from about 5.5 gr for Blazers with most 4" vanes weighing about 8.5 grains each.

I think you will find the weight being more than stated on vanes. The blazers that I had weighed in at 7.2grs and the killer vanes were 12grs each. The vane tec 2" come in at 7grs each. Or my scale is off!
Pat