With 300 feet of mainline, finding an inexpensive way of fabricating catenary led me to experimenting with common materials. The methods of construction, while economical, produces a sturdy assembly after a few sections are completed. You won't find many exact measurements in this instruction, only enough of them to make rough duplicates of sub assemblies. Unless you have long mainline straights, the dimensions will need to be tweeked to suit a tunnel, bridge, curve or switch. Because of this, you could say I'm building this by eye rather than from drawings. Having the ability to envision the finished product installed sure helps here. Any questions, hints or tips are really welcome, since I'm flying solo.
Materials:
1) Mild steel TIG rod, 1/16" X 36". The copper coating on this type welding rod also makes it ideal for soldering....and you will be doing a lot of soldering. The rod will bend but is brittle enough to break on the second or third bend. Cutting is done with side cutters, scoring the rod with a slight squeeze, then bend to create a clean break. This is the type rod I have access to...1 pound, or 34 rods cost $10.00. Well equipped automotive stores should offer a similar brand.
2) 1/4" hardwood dowels. Found some measuring 12" long at a dollar store. These are surprisingly sturdy enough that once connected together by the rods, a really solid assembly is produced.
3) Solder. Use a rosin core type...you can avoid coating with flux by using rosin core. I just happen to have a supply of 53/47 that works quickly and creates a robust bond.
Tools:
1) Wire snips/ side cutters.
2) 3', 2X4 for a jig.......I used cedar...smells good when burning under the soldering iron.
3) Soldering iron or gun
4) Favorite drill with a 1/4" and 1/16" bits.
5) Metal clamps or small vise grips.
6) no fear
Sub assemblies.
Survey the layout to figure out where best to begin. Preferably on a straight section of track, without surrounding features to interfere, while you get your construction feet wet. Decide the width need to span your track and drill 1/4" holes in your benchwork where the first 2 dowels will go.
At the bench, I take the 2X4 and transferring the width measurement, drill 2 holes, say, 11" apart. Line up 2 dowels, measure and drill 2 holes through each dowel, approximately the height of the cross bars between the poles. I choose one crossbar measurement for the entire layout ( 1 1/2" down from the dowel tops )...that way the tops of all the poles crossbars line up once installed. Drill 1/16 holes about 1" into each pole top. Insert the bottom of the poles into the 2 holes in your 2X4 jig.
Fashion 2 crossbars from the rod, roughly 11 1/2", insert through the dowels and bend at the ends. Forming an M shape from another length of rod ( these take a bit of skill ), insert the ends into the dowel tops. Ideally, the V just touches the top crossbar but overlapping is OK too.
Here's where you begin to solidify things up by soldering the crossbar tips together and the V bottom to the crossbar. I don't glue anything on these upright assemblies. Between the 2 crossbars I bridge the gap at a few places by dropping in a short piece of rod between the two and soldering all 3 together. All that remains is to drill and install angled bracing, soldering the top end of the braces to the bottom crossbar. The photos should help guide you better than any description.
The end result in the jig.....more on the jig next time
Those little metal clamps keep things aligned when a 3rd or 4th hand is inevitably needed while soldering. You'll appreciate how easy it is to solder this material, with the rigidity to avoid accidental warping or bending as with softer metals. That ability to keep it's shape really assists in producing a trolley wire that doesn't deflect under a spring loaded pantograph. No need to build in tension to the trolley wire to keep it taught. Another benefit is the rod conducts heat poorly. Many times I found I was holding the rod an inch away from what I was soldering, and no burnt pinkies. We'll get to making the trolley wire stringers next.
Bruce
