I moved into a new house and no longer have room for a practical HO layout, so I was considering building a tabletop n-scale deal. What's the tighest radius you have been able to run an engine? I figure to probably be using a 4 axle diesel. How about the tightest radius for a steam 2-8-8-2 type? I realize there are many factors if you want to get technical. I'm just looking for a rough estimate. Thanks.