Herb ground to a powdery consistency, with most vapes, is too fine. Most quality vapes are convection, where the heated air passes through the herb. Most screens are going to allow powder to pass through-not good. The Volcano is certainly not a model that would require a very fine grind. A few vapes, herbalAire and Vapolution are two that come to mind, work much better with pieces instead of ground. Both of those models would pass way too much uncooked herb beyond the bowl, and the herbalAire does such a good job, efficiency wise, that there's simply no need to grind at all.

A powdery grind is good for conduction vapes, where the herb that contacts the hot surface is the part that gets vaporized. The only good conduction model I can think of is the Magic Flight Launch Box. The screen on that one is so fine that pretty much nothing can get through.

A normal grinder will process herb just fine for a whip vape like the Easy Vape.