Bill:
I held the prop in a press clamp, used a drill press, and used 4 bits to reach 7/16's. I did not clamp the holder to the press and align with current bit size. I will next time. Got a Bolly 20X10 coming and don't want to mess it up.

To answer your question on vibration, it is on the low end, roughly at a very high idle. All the control surfaces really vibrate. I was told this was normal for a gasser but I don't like it. I think I can see at the hub where it meets the prop (no spinner yet) and see some miss-alignment when it turns. That is why I think maybe I did not get the hole true. However, I did balance it using razor blades and a hand held balancer. (to heavy for my normal magnet balancer)

One word of caution! I used graphite rods and titanium 4/40 ends that I got from Central Hobbies. They recommended using quick setting JB weld which I got from them. 2 of the rods came loose after 4 flight. Fortunately, when I was flying it, it noticed the trim was changing on me so I quickly landed it. The ends were loose and would move, causing the trim change. I removed all rods, replaced, and used 30 minute epoxy. I think the JB weld set to fast for any penetration and will never use it again......

Thanks,
Paul