07-22-2009, 09:00 AM
Josh, have you got any of your freight cars built, yet? I measured an f-unit and found it to be about 2.5 inches tall. I suspect your power units will be about the same height as an f-unit. Measure your tallest car, add an inch for clearance and the thickness of the table and track and you have the amount of elevation you need to gain on each rotation of the helix. You need to have the helix base strong enough to eliminate sagging. You can't use an "L" girder type of construction because the extra thickness of the "L" would increase the distance the helix would need to go up in order to clear. If you made your helix base wider, say an extra inch to inch and 1/2 inside and outside of the tracks, you could make it like 2 upside down "L" girders, in other words a "U" channel. In that case, the base could be kept thinner and flexier because the sides would stiffen the bench work.