mike g. posted:Hi Guys, thanks for the nice words! I feel a lot better as my mind is now clear and ready for more train work!
So here is my lunch time up date! I got my first switch mounted and worked on the airfield! From a suggestion from Paul2 I hung the end of the runway over the lower tracks ! It will have to tunnels under the airfield. But I do have a question, can someone tell me the inside dimension of a single and double porthole, say MTH or Lione it doesn't really matter I don't think!
Mike- gotta watch the over hang with tunnel portals on curves. Take your biggest loco or rolling stock and mark the clearance needed to travel the curve. I do it by holding a pencil at the widest point, usually a pilot step or cab hood on a steam engine, and draw a line on the board as you move the piece through the curve. Do the same in the center for the inside of the curve. Do this in both directions too. Geometry is a PITA 
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Once you have the lines on the board you can determine how big the portal needs to be. Make sure to add at least a 1/2" on both sides.
Bob
