You can use a bench grinder to rough in the bevels. Just be doggone sure to dip them in water every few seconds to keep the material cool or you will mess up the temper of the steel. Once you have most of the bevel done on the grinding wheel your Lansky should do better.
I use the Gatco sharpener on my broadheads, similar to the Lansky, but with wider stones for more contact. Something nice about repeating the exact same angle on every stone stroke, ya know?