Ore Bridge Model - Chapter 4

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Last week I had installed the rails for the tram, and finished the basic frames (i.e. minus the diagonal braces) for both the main bridge and the dockside extension. The next step was to connect the two sections; in addition to some sturdy strip brass, I also needed a set of hinges which I found at my local hardware store, plus some size '2-56' specialty bolts and nuts from a hobby shop.

Wiggle Room

I knew from the outset that it would be a challenge to keep the tram rails aligned on both the main bridge and the extension, so I didn't want to solder the hinges directly. Instead, I attached some mounting plates to each section where the hinges were to be positioned. I drilled some extra-large holes through the mount plates, so that I could calibrate/realign the hinges as needed; I also made a single plate for each pair of nuts, with holes just wide enough to accommodate the '2-56' bolts:

ob_model_hinge_plates.jpg

The purpose of the 'nut' plates was to avoid having to position a wrench on the backside [to lock each nut in position] while tightening the bolts on the front end. I soldered each nut to the nut plate:

ob_model_hinge_nuts_soldered.jpg

I then bolted the hinges to the loose mount plates...

ob_model_hinges_top.jpg

...so I could hold them against the separate bridge sections and determine where the mount plates should be soldered-on. Next, I removed the hinges and soldered the mount plates in their target positions. When I reattached the hinges to the plates on each bridge section, I had to loosen one of the bolts on the extension so I could tweak the alignment.

Planning for Future Enhancements

Even though I do not plan to immediately build a fully-mechanized tram and hoist (I've still got a layout that needs to be built), I realize it is better to add the track wiring NOW than to modify the completed/painted ore bridge retroactively. So, I needed to procure some wire that was thin enough to be hidden inside the frame tubing. I was able to drill holes on the 'main' side frame [to insert the wires], but I needed to add sleeves to hide the wiring on the extension side:

ob_model_wire_sleeves.jpg

I thought about soldering the sleeves on (it would have been a lot quicker), but I decided I didn't want to risk melting the wire insulation inside, so I expoxied them instead:

ob_model_wire_sleeve_glued.jpg

Now I was satisfied that the wiring wouldn't stick out like a sore thumb. I did a final connectivity test on each track spanning both sections before moving onward. (I had hoped to borrow somebody's Northwest Shortline PDT self-powered truck to test the track power, but unfortunately my modeler friend was out of town at the time.)

Here are some closeup views of the attached extension in the UP and DOWN positions.

An interesting possibility...

As I was helping my wife tidy-up the house for expected guests, I discovered something that may be perfect for raising and lowering the clamshell bucket: a motor/gear box from my kid's K-Nex set. It would fit nicely inside a styrene enclosure, has loops for hanging underneath the tram, and has axels both parallel and perpendicular to the motor. It rotates slow enough to resemble a prototype hoist. Hmmmmmm.......

KJL