Thank you, John, I agree with your point. In fact, I have a customer he want to drill a hole for making a pen, but he complained he couldn't drilled the hole accurately, because the center was different height. (it is about 0.30mm difference) So, the hole of another side will go beyond the center a little bit. I goggle many about making a pen courses from network, some turner drilled a hole first, then using a pen-kits through the hole. Even the hole was oblique, they could hold both side of kit by spur center, and then turning the wood. The finish product seemed good, and the hole was in the center after turn out the rough part of wood piece. Do you think it is possible to do that? Because I don't have this kind of kit for making a pen, so I appreciated someone who has ever used this kind of kit could give me some opinions.