Ore Bridge Model – Chapter 7

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Building An Operating Clamshell Bucket

Since I am still waiting on the delivery of some engraved gusset plates, I decided to focus on something not bolted to the bridge structure: the clamshell bucket.

One modeler who has already built an animated ore bridge model mentioned that his greatest challenge was to construct an operating clamshell bucket, so I wanted to finish this sub-task as soon as I could.

The concept seems simple enough. Two cables carry and control the bucket: One to close the bucket around a load and hoist it upward (I'll call this the "close/up" line), and the other to draw the two halves apart, release the load, and lower the open bucket back down for another load (the "open/down" line). The last time I checked, there were a few brass HO scale clamshell buckets commercially available; so I believe my friend's dilemma was developing a remotely-controlled, tram-mounted mechanism to control the two cables. Since I have committed to laying 99% of the track on my new layout before attempting to animate the ore bridge, I'll sweep that little problem under the rug for now. But I still need a bucket of the proper shape and size that will open and close reliably, so that is the focus of this 'blog chapter.

The prototype I chose to base my bucket model upon is on a bridge in Superior, Wisconsin; the photos are from a book titled "End Of An Era" by David Plowden, about the few remaining steam-powered lake freighters. [ Since the pictures are copyrighted, I cannot display them here. ]

I opted to build the bucket from scratch, using K&S^® brass sheet and 1/16-inch square rod. The sections would swivel on 5 separate Ives^® miniature brass hinges; the major components were to be soldered, then joined to each other via 1/8-inch size '2-56' bolts.

Since I was unsure of whether my planned approach would be successful, I did not shoot any photos until after the work was completed. If I ever write a how-to article, I'll redo the process and take extra pictures at that time. But, for what it's worth, here are the snapshots that I DO have, showing various stages of completion:

1. Sheet brass with cutting outlines for the side walls. I shot this photo before I discovered that the bottoms are linear, NOT rounded - the correct cut lines are superimposed.
2. Some source materials left over at the end, with precision tools for tapping and driving the miniature bolts.
3. Two halves of the bottom section joined by a hinge, with another two hinges soldered onto either end, with excess material cut away before attaching plates.
4. Bottom section after plates soldered-on, showing how center holes were tapped-out to accept a 2-56 bolt.
5. Underside view of top hinges, joined by a 1/32-inch thick piece of brass strip, with a hole drilled into the center to accommodate the "close/up" cable.
6. Overhead view of top hinges alongside the two vertical frames.
7. The assembled bucket
8. Mock-up test of close/up cable functionality.
9. Mock-up test of open/down cable functionality.

(Further detailing of the vertical frames will be added later.)

...and that's all for this first week of 2004!

-KJL

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