MELGAR posted:Picture shows the scratch-built trestle and through-truss bridge on my 10'-by-5' layout that is the subject of an article in OGR Run 304. Both bridges are 24 inches in length, constructed from basswood, and easily removable from the layout. I made an accurate sketch of the truss on a sheet of graph paper, determined the geometry and dimensions needed for construction, marked and cut all truss members with a razor saw/miter box, and filed or sanded until the fit between the upper and lower horizontal main truss beams was just about perfect. Assembled the trusses on a glass plate (covered by waxed paper) to maintain flatness using masking tape and weights to hold pieces in position until the yellow carpenter's glue dried. Similar process was used to establish geometry of trestle bents. Since the bents were small, I marked a thin sheet of basswood with locations of the "vertical" beams, taped and weighted the pieces down flat and glued them to the top and bottom cross members. Could have made a small jig for the trestle bents but did not think it was necessary. Then inverted the bents and glued them to the longitudinal members with spacing 1-1/4 inches (same as rails). When all bents were in place, carefully turned assembly upright and installed diagonal/horizontal braces. The longitudinal rail support members rest upon "stone" abutments at each end. Truss bridge members - all cross sections 3/8-inch wide with depths of 3/16, 1/4 and 3/8 inches. Trestle bent "vertical" members and longitudinal members supporting rails (both bridges) are 1/4 inch square cross section. Used a steel rule and small 90-degree triangle to assure perpendicularity of all members on both bridges.
MELGAR
Wow - really cool!
