Wednesday, February 11, 2015

Catenary Update: Learning from Mistakes, Advice from Wire Jedi, and Test Run Video

Catenary is mostly installed and finally resulting in successful test runs on the Dunes Junction, as seen in the quick-and-dirty YouTube video above.

There's been quite a bit of experimenting to get to get to this point, but I've got the hang of hanging catenary now. Translation: I hung, tore down, and re-planted poles and re-hung and adjusted catenary.  Others call it failing, but I call it learning, and it has been a rewarding process. And still no burnt fingers!

I actually got catenary up over the entire main line, and initial testing wasn't pretty. My MTH 800 (Little Joe) dewired regularly, and some of my other test models--a Bachmann E33 and and Atlas AEM7--fared somehat better.

Insufficient tension and too long of wire runs were the culprits. My pole distances were wrong--spaced too far apart, and not uniform. I removed and repositioned poles to achieve a uniform 19" spacing for the 20" stock Model Memories catenary sections, and also made a hidden anchor bridge from heavy brass stock that is neatly tucked behind the US 12/20 overpass to address the tension problem.

At first, the respaced poles and rehung sections worked only marginally better for the 800, with dewirements continuing. I admit, I was disheartened. So I reached out to two people I who know a thing or two about model catenary: Don Silberbauer of Model Memories, the maker of catenary components I use; and Rick Abramson, New Haven modeler extraordinaire and HO heavy electric expert who has been blogged about here previously.

Thanks are due to Don and Rick, whose heavy electric Jedi abilities include sensing a distressed fellow heavy electric modeler across vast distances.  Both of these generous gentlemen promptly got back to me with advice and encouragement.  Most importantly, Don and Rick affirmed that trial and error and an embrace of momentary failure are an essential part of the model catenary experience.

Both pointed out that the pantographs on most commercially available HO models are for show only, too tightly sprung or otherwise barely functional.  "The manufacturers never figure on the pans actually running under wire," Don wrote me via email. The excess upward force caused by the tight springs on the MTH model was at least contributing to dewirements.

Rick echoed that observation during a telephone 'pep talk' that ultimately inspired me to go back and double check my wire work. He also mentioned wire "flapping in the wind"--without appropriate tension or rigidity--as a possible problem.

I went back to my wire work and discovered that not only did I need more tension, I also needed to be more conscientious about gauging, or centering the wire over the rails. The angle and direction of my work on the wire is dictated by the fact my layout is on a shelf and is at shoulder height. Unless I take extreme care, the wire ends up to the inside of the gauge because I see the gauge blocks from the side rather than directly above, and thus I discovered a consistent bias to my wire gauging. The comparatively narrow shoe surface on the 800 pans didn't react well to the inside-leaning wire. But my recheck and fixes of the wire gauge appear to be working well with the 800 now.

So now my main line has working wire, as seen in the YouTube video above. Woo hoo! My next step is wire over the crossover, about which I am nervous. A final touch will be painting and weathering the catenary. Look for future posts on my wire progress!