Frame Construction Part I
It was the spring of 2006. The miscellaneous engine parts had all been fabricated and the boiler was being made so the next thing was to finish the frame design and construction. Five weeks volunteer teaching in Central America where there would be a lot of free time to work on the frame design was coming up in two couple weeks. The design and fabrication of those slotted stiffeners that distinguish the late Heislers filled those two weeks.
Center Stiffener: The design of the stiffener is documented in the Frame Design II page (done after the stiffener was actually built). The stiffener is too complex to machine as one piece. However, after a bit of thought it became obvious that it could be build by soldering together a bunch of relatively simple parts. If the part is small and requires a lot of machining, brass or bronze is a good choice. For larger parts, steel is cheaper and hence preferred unless considerable machining is required. Kozo Hiraoka is an expert at the technique of modeling castings by silver soldering together smaller pieces. Many of his techniques have been used to make these and other parts for both the Shay and the Heisler.
For this center stiffener, not much intricate machining is required so steel was the choice. (It also helped that all the required maternal was on hand.)
Modified Stiffeners: The basic center stiffener design was later modified with the addition of a bar (HM419) along the bottom that interfaces with the center boiler support. This modification is described in the Frame Design III page. The bars are lengths of 3/8" X 1/2" bar stock The recesses were rough cut on the band saw and finished on the mill. The lower 1/2" of three of the vertical bars were rough cut out using a rotary tool abrasive disk and then finished on the mill. A #2 FH screw into the bar from the back holds the bar in position while it is silver soldered to the rest of the assembly. This time short strips of .004" thick flat silver solder and flux were sandwiched between the bars the the rest of the assembly and then the assembly heated. The photo below shows the two stiffeners after the modification.
Note that the stiffeners are no longer identical since the added bar is off center. The left stiffener is on the left in the photo. The left stiffener will require further modification to accommodate the reversing bar rollers. The right stiffener will be modified to accommodate the lubricator. The holes to attach the stiffeners to the frame side and to attach the center boiler support to the stiffeners must also be drilled. Those issues will be dealt with later.