Mana curve suggestions?

You have to list cards with X is their cost in a separate category. You really need more than one copy of the key in your deck as that grindclock doesn't work too well as is. If you were able to put a counter on that grindclock AND mill the same turn would make that card remotely close to good, thus the four copies of voltaic key. You also need four copies of the grindclock because an artifact is more useful in the long run than a sorcery. Also that crab is not terribly useful if you don't have landfall in your deck because without the landfall it is too slow. If you plan on making that a big part, then you need to throw in some tap to look for a land lands, like terramorphic expanse or those expensive ones that you tap, pay a life and sac to search for one of two basic lands. So unless you want to go for the crabs and add in the land search, I would take those out and add more grindclocks and voltaic keys.