Building laminated sub-roadbed on a flat surface
Where the shelf connects to the rest of the railroad, the completed roadbed is cantilevered from the last riser (aboveleft). The center spline on the left has been set in a groove to check the alignment
(aboveright). At this point it is apparent that the polyiso base has to be cut to the full width of the roadbed, plus the outside joint splices. A chisel was used where the foam had been glued to the support.
The completed joint (left) passes through the polyiso foam base and is supported where the bottom reaches the top of the base. The grade is six percent. Where the switch back to the reload meets the base (bottom left) meets the base, the center- line has been marked and the slot is cut with an ordinary serrated steak knife.
by cutting a slot in the foam for the center piece of spline and gluing the center piece into the slot. That is what we tried first. Because the plan called for a continuous grade through the transition from open grid to the shelf, it became apparent that this wouldn’t work. We had to cut an opening in the foam shelf wide enough to take the full, 13 piece laminated sub-roadbed, plus splice supports. The accompany- ing photos show how this was done. Next, the essential center spline was put into place. First we screwed 2″ dry wall screws into each upright on either side of the centerline. The center piece of spline was then put in place between the screws on the uprights. The result was a series of beautiful, undulating curves, with no straight sections. The secret to straightening the spline lies in hot gluing on additional pieces cut to the needed length. These will strength- en the spline and hold it straight. It takes two or three pieces on each side to keep straight spline straight. Once the straight sections are set, additional spline pieces can be laminated onto the curves to strengthen them.
The first four feet of the shelf is four
position. Then a question arose. How can we make the transition from the laminated sub-roadbed over open benchwork, to the shelf portion of the
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railroad with its laminated sub- roadbed supported by the uprights? We had previously made the transi- tion from foam base to laminated base
inches lower than the remainder. The transition takes place on a curve in the track. Once the location of the track was marked, we cut a slot wide enough to contain the whole sub-roadbed. Remember what I said about doing the upper level first? Now came the real headaches.
JUNE 2014
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