You could modify it a little. Mazzer had the same problems,
and this is what they came up with.
it's an auger (like a feeder). Apparently a customer of Mazzer in the States complained the grinder would not grind the beans he roasted, after debate and analysis the problem showed to be the size of the roasted coffee. This guy managed to find and roast wee beans that were so big, that they just bounced around the top of the burr set rather than slipping and being ground. So Mazzer added this thang to their grinders a "bean cutter", something that looks like an office fan that cuts them beans up before they drop into the burr set. They found that this auger stopped this popcorn effect that troubled Mazzer grinders with a small amount of beans in the hopper, and happily also 1. ground beans at the same rate regardless of the amount of beans in the hopper, and 2. ground beans quicker. A success, if you ask me.
This is all according to Mark Prince, from a post on the coffeed.com forum, ta.