Get yourself both a 60 deg. live and dead center. The point on the standard wood lathe center is to sharp and will move around in the hole in the end of the mandrel eventually ruining it and could result in out of round pens. There is a guy over on IAP (JohnnyCNC) that makes excellent bushings for the pens. They go between the centers and a mandrel is no longer needed. They are a little more expensive but worth it if you are going to be making a lot of pens. They also have a pretty extensive library on penturning