I acquired a Shimpo-West ring-cone popet wheel, which works well (and was an absolute blessing to get from a woman who ran the arts program at an old YWCA camp). I'm having trouble with bats. I tried drilling holes in plastic bats I already had, but I'm having trouble getting a tight fit on the wheel head since the posts are cone-shaped. I do not have the original manual, and the shifting while throwing is not working for me. Does anyone have suggestions for drilling more accurate holes, or even a source for purchasing a pre-drilled bat?