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Last month, I had cemented all of the inner frames to the top horizontal girders, then notched those and bent them downward at the inland (or �furnace�) end.� Shortly after that, I soldered together the bottom braces that support the tramway:
Now I was able to permanently attach the bottom [inner and outer] horizontal girders, which I did.� At this point I was ready to try the �acid test� � seeing if the existing brass material was strong enough the support 2-3 lbs of hanging weight in the exact center.� I tied half of a brick to my daughter�s shoelace and tied it around the bottom girders, and here is the result of that experiment:
It appears to me that the bridge will support an HO scale motorized tram and brass clamshell bucket when I decide to add them.
The next challenge was to attach a pair of rails to the center bottom horizontal girders, for the tram.� I dreaded the thought of trying to cement each individual rail on either side while ensuring that the two stayed perfectly parallel, so I started with something guaranteed to be properly spaced � a 36-inch section of flex track surrounded by 1/4� angle girders of identical length:
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The angle girders would fit flush against the ties; to ensure that the rails would remain perfectly straight, I used two aluminum angle rods to support the rail subassembly�.:
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�holding everything together with clamps:
Mixing up a liberal amount of J-B Weld, I poured this into the cavity between the rail and the brass L-girder on either side, making sure that the outer ends of the plastic ties were completely covered.� The following image shows a cross-section of a piece of the rail subassembly after it was cut off:
Notice how the outside edge of each rail is bonded to the J-B Weld, which is bonded on the opposite side to the angle girder.
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The end product after removing the supporting aluminum L-rods was a 3-foot section of brass-encased track�.
�which slides right into the inner bottom L girders on the bridge:
All that remains is to solder the track girders securely to the bridge girders, then cut-away the plastic ties from the center � this will be done later.
Shortly after performing the above steps, I saw another photograph of a lake-front ore bridge where the inside braces were visible, and my reaction was about the same as with somebody who has a mild toothache and hopes it will just go away, but ultimately has to get a root canal.� The �root canal� equivalent for me was having to rip out all of the �X� braces in the taller vertical frames and replace them with �X-W� configurations:
This resulted in a 1-week delay on the ore bridge project.� I placed an additional 5/32� channel piece horizontally across each frame�:
� but replaced the original brass diagonal braces with .125�-square strip styrene on the �X�s and �W�s.� The styrene fit snugly into the open channel sides of the frames, and the gusset plates � also made of styrene � bonded easily to the new diagonals.� I made extensive use of the Chopper to get the appropriate shapes:
Here is a view of the bridge after the correct inner brace configurations were installed:
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Now I was ready to complete the drawbridge-like extension for the waterfront end of the bridge.� Aside from being only ten inches in length and half the height of the main structure, the construction methods were the same, so I�ll only show two photos of the intermediate assembly process:
Before permanently attaching the track sections to the bridges, I soldered some electrical wires to each rail so that I could use a powered tram/bucket hoist in the future, should I desire one.� Then I soldered the L girders of the tracks onto the inside L girders on each bridge and cut away the centers of the ties.� I did this by first using my Dremel cutting wheel to grind a gap in the center of each tie, then using rail nippers to clip the leftover tie pieces from each side.� Why the center gap? Because without it, the pinching motion of the rail nippers will exert outward pressure on the opposing rails (probably harmless, but I didn�t want to risk any more glitches).
Here are three images of the semi-completed bridge assemblies viewed at different angles:
My next planned operation is to install the connecting hinges between the main bridge and the retractable extension.�� I�ll post those photos when ready.� �KJL
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