Archive for August, 2013

Missenden coaches

Posted on August 24, 2013. Filed under: Project progress |

Yet again the Missenden Summer School has given Kyle of Sutherland a shove in the right direction. In just under five days I made two basic running coaches from Comet kits.

Coaches 6 Comet LMS 1 130824       More LMS stock for Kyle of Sutherland

After my experience with Sc6735M built in some detail from an Alastair Wright kit (five or six months work), I decided on a more pragmatic approach to coach building. I’m building these two straight out of the box with as little embellishment as I can get away with. The Open Third on the left will run within a fixed rake, where the coach will only be seen in side view. The Brake Composite on the right is planned to be a good copy of the single Dornoch coach in a 1959 colour photo in a recent Steam Magazine. I’ll put more effort into the ends for this coach.

Detailed or not, exhibition coaches must run well. These coaches were bought at different times with different bogie designs. This has allowed me to have one part-compensated bogie and one bogie with secondary springing on each coach. How well will they run?

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A new servo suggestion?

Posted on August 14, 2013. Filed under: Project progress |

Locos vary in their current consumption, and in their ability to upset servos. My old Triang-motored shunter is useful for checking servo behaviour, even if it’s not reliable enough for exhibition use.

As well as checking that the exhibition locos don’t cause the signals to twitch, why not use a known twitcher to experiment with wire routing. Even a reduction in the likelihood of twitching would presumably benefit the non-twitchers, if you see what I mean.

Or am I just super-sensitive to servos?

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Postscript to incremental design

Posted on August 11, 2013. Filed under: Project progress |

Servos can be a pain! The Down Home worked fine with the new signal wires (actually a new servo with its original, non-extended servo wires) for the KoS locos (one Portescap, three Mashimas and a Bachmann motor), but not with my old Triang-motored diesel shunter on the Up line. The signal arm did not twitch, but simply moved from Off to On, and beyond, as the loco passed through the area around the switched common crossing (SCC) on the loop point.

I reasoned that the problem was that the signal servo wires were virtually surrounded by common return wires, and when the point was set to Up, the SCC was also set to common return. When I re-routed the wires looped around three sides of the servo board and moved the servo board further away from the track, the loco did not affect the signal.

I am claiming this as some sort of success, but still find it irksome to have to go through these hoops (loops?). However, it’s given me the confidence to continue with servo-operated signals, and to finish this round of wiring mods. The Up Starter will have to wait for me to produce another servo board: it’s too far to plug into the Down Home board.

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Incremental design

Posted on August 8, 2013. Filed under: Project progress |

It’s time I carried out more electrical modifications on the layout, but those twitching servos have got me worried. When I say “twitching servos” I mean the signal servos that twitched throughout Scaleforum 2012 and which I’ve not yet sorted. Something to do with the proximity and alignment of track section feeds and servo control wires.

??????????       Who knows where the wires go?

The cut-out for the Down Home is made and it’s decision time for new wiring. Where to route the electrics to add a new section between the loop point and the south cassettes, the DPDT switch to isolate or feed the new section, two new Fulgurex changeover switches, and those signal servo wires and power switches? It doesn’t help that the signal cut-out is bounded by electrical section feeds on three sides and track on the other.

This is when I wish Kyle of Sutherland were a second layout. I might then have some experience to call on, instead of continually dealing with the consequences of incremental design.

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July progress

Posted on August 1, 2013. Filed under: Monthly progress |

This last month I’ve mainly concentrated on the operational side of Kyle of Sutherland. When it next appears in public it must work smoothly, as well as be complete.

The layout can now be operated in two independent halves, and this allowed me to thoroughly test my three controllers together with my five locos. As a result, “Pictroller 193” now has a new Forwards/Backwards switch and, in combination with “Pictroller 192” and my original Pentroller, everything seems to work fine.

I still feel the operation of the Router is not sufficiently intuitive, so towards the end of the month I designed a new Router. Instead of a rotary switch for “Up” and another one for “Down” trains, the new version has a rotary switch to designate the active controller, and another switch for “Up/Down”. This involves adding further switches to the Fulgurex-operated loop point. Unless someone comes out with a reasonably priced 5P 6W rotary switch, I feel I’ve reached the limit on traditional wiring. And I’m not yet minded to move into the world of relays.

I also feel I should wire signal servo operation through point switches to emulate the interlocking on the prototype. It would be no bad thing to only pull off a signal if the point were set correctly.

And, by the by, I found that the problems with 57587’s tender were caused by not enough side play on the leading axle. Ho, hum!

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    The epic struggle to build a model railway exhibition layout at 4mm to the foot

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