Sunday, February 26, 2017

Track Permanently Down at Gunnedah

It’s been a little over three months since my last update, and I am happy to once again report that there has been a degree of progress on the layout. Having a quick look back through this blog, December 3, 2008, was the first post that outlined my desire to model Gunnedah, and here we are a mere eight years and a couple of months later, and there is finally track and points down permanently in what is a slightly condensed representation of Gunnedah yard.

Of course out of that eight years, actual layout construction only began roughly twelve months ago, so under the circumstances of this build and the amount of work that has been done, I am overall very happy.

Unfortunately the past twelve months has also seen a steady progression with my motor neuron disease, the past three or four months seeing my legs affected to the point where walking has gone from being slightly challenging to basically impossible. I can only stand if I am seated on something no lower than about 62 cm high, and even then can only stand for about 30 seconds or take about half a dozen steps before my legs basically give out. This has made it very difficult to even get down to the train room, and while there are modifications being made with various ramps, and equipment being ordered to help get down there, it is nonetheless extremely difficult.

However, with the help of family and friends, I still hope to be able to keep going with the layout and get as much done as possible within whatever time period I have.

Anyway, I digress slightly, so back to the actual progress.

My Dad spent about a week with me in December, and during this time we concentrated on getting some track stuck down to the foam underlay in preparation for it being stuck down to the modules. Point motors were also attached to each set of points as well as the foam underlay stuck to each set of points. With about twenty-four sets of points in the Gunnedah yard section of the layout, that task alone was a substantial one, taking into account that my Dad is not a modeller in any way, shape or form, so there is a fair degree of explanation in how everything works. Coupled with the fact that some of the things I am doing are slightly less than conventional means that I am experimenting as well, so it is a bit of a task at times!

Starting with the approach to Gunnedah, which on my layout is a single line of curved track with a radius of about 28 inch, and a single set of points on a corner module, track and points were permanently attached. As the foam is less dense than timber/plywood, using track pins is not an option, but after hearing a few other people using the method successfully, I am using Parfix silicon sealant to attach the underlay to the track and to the foam module. A smear of silicon is all that is needed, and once dry provides a firm bond.

It might seem like a very small step, but seeing that first meter and a half or so of track and a set of points permanently attached was quite emotional for me. The decision in the beginning to get the majority of the layout construction finished before laying any track has paid dividends in a lot of ways, but it has been a long twelve months or so waiting for track to permanently begin to be laid so that trains will be able to be run in some form.

After a small break over Christmas my Dad came up again for another visit later in January, and this time with some extra help. After discussing what we were doing with an old friend of his, his friend said that he would be interested in seeing what we were doing and lending a hand. Whilst not necessarily knowing a lot about model trains, he has vast experience in repairing electronic products specifically used in the music industry, wiring up recording studios etc, and also has a drafting and mechanical engineering background, so is someone well suited to solving some of the technical challenges that building a functional layout sometimes present.

The first solution he came up with was in relation to mounting the lightbulbs which are a visual form of short circuit protection and detection. I had not put too much thought into the actual design as until that visit not all of the lightbulbs had even been added to the main bus wiring. After his visit he emailed me a drawing of what he had in mind, a rather elegant and practical design that was also simple to make, cheap, adjustable and robust. It is no more complicated than a length of coathanger wire (or similar), formed into the appropriate shape which simply wraps around the bulb holder, and then with two small holes drilled into the timber section that runs around the front of the layout that the bus wiring is mounted upon.

Once installed in place, the lightbulb bracket is held firmly but is still easily able to be slid forwards and backwards, so that once the layout fascia panels go back into place with an appropriately sized hole for the lightbulb to poke through, the lightbulb position can be adjusted so that they all poke through the fascia panels by the same amount, I’m thinking the tip of the bulb will sit about 4-5mm proud of the fascia panel, enough to be seen easily from any angle when lit but not enough to be easily bumped or be too obvious.

The January visit also saw track and points go down permanently on the corner module at the opposite end of Gunnedah yard, which has about five sets of points as opposed to a single set at the other end, and a pair of these points which form a crossover will need to operate together at the push of a single button. I will go into more details on the point motors and their activation at another time.

With track and points permanently attached to the two corner modules, it was time to begin the wiring on the underside of the modules. This is where the modular construction really starts to show its benefits. Being able to lift each module down and lay the track upon it on a bench in the centre of the room was much easier than having to lay it in position on the layout, but the ability to flip modules upside down and work on the wiring at a comfortable height with it all facing upwards was so much easier than working upside down at an inconvenient height.

All of the track and points have had red and black dropper wires (and a green wire off the point frogs) soldered to them prior to being stuck down, and it was a simple matter of poking a screwdriver through the foam base to make an appropriate sized hole, and pushing the dropper wires through. With the module flipped upside down all of the dropper wires are poking through ready to be joined to the module bus wiring.

With the dropper wires and point motors poking through, it was a simple matter of running the heavy red and black bus wires in a convenient position and then soldering the dropper wires to them. The heavy red and black wires are also brought through the timber frame at the front of the module with a two pin connector that joints up to the connector on the main bus which runs around the layout. This system allows for simple electrical connection to each individual module when they are placed into position on the layout.

I have been very careful to stick to a wiring convention where all module to bus wiring plugs are wired identically, so that for any testing any module can be plugged up to any convenient part of the main bus wiring and it will work.

Whilst track wiring is relatively simple as it is basically red and black wiring, the point motors introduce a slightly greater degree of difficulty. I am using the Cobalt iP Analog point motors from DCC Concepts in Western Australia. They essentially use a five wire system, two wires for the DC switching to move the points left and right, the red and black dropper wires from the track go to two other positions, with a green wire that comes from the point frog going to the fifth position. As the points are switched from left to right the polarity of the frog is changed accordingly.

As Gunnedah yard has a large number of points, I wanted to be able to identify the trigger wiring for switching points easily, and as a few sets of points form crossovers were a pair of points will always be switched together, it made sense to use a combination of wire colours to identify a particular set based on their orientation and being a single set or a pair forming a crossover.

Essentially each set of points is identified as being left-hand clockwise, right-hand clockwise, left-hand anti clockwise and right-hand anticlockwise. This gives four combinations, all of which are noted in an exercise book I have which clearly identifies all wiring, plugs, transformers etc for future reference, troubleshooting etc.

Each point motor is also identified depending on which module it is on and its number, so once the trigger wires are run from the point motors in their various colour combinations, they are also marked with what points they are coming from. In theory this should mean when it comes time to plug all of these wires up to the boards that handle the point activation, it should be very simple to identify which is which.

For the time being whilst the modules can be tested to make sure everything is working properly, the wiring has been temporarily held in place with masking tape. Once a degree of testing has been completed and I am confident there are no issues a more elegant and permanent solution will be used to retain the wiring in place.

Following January’s visit, my Dad came up for another visit in February and his mate also came up for a couple of days, this visit saw about 80% of the track in the middle section of Gunnedah yard permanently attached, and about 60% of the wiring underneath the module completed. This centre module contains the bulk amount of track and points, and will be by far the most time-consuming part of the layout to get operational. Hopefully further visits will see this part of the layout completed, at least as far as track work goes, which can then be tested and trains run finally.