Fresh(er)water wiring completed

A weekend exhibiting Coley Park at Yeovilton followed by a weekend in Slovenia on a business trip slowed progress, but last week saw the completion of the wiring for the point operating servos to a 'temporary' switch box which will be replaced by Merg CBUS control one day. Unfortunately, two of the Merg Servo4 controller circuits I built last summer failed to respond to the setting up box. I only had 5 of the 7 points working.

However, I checked the Merg forums and it seems that there was a fault with programming the PIC microcontrollers for the kits last year (since fixed). An email to the Merg kitmaster saw a speedy response, and two new microcontrollers turned up in the post this morning. They are now fitted and working, and the two faulty ones will be returned for re-programming. Many thanks to Martin (Merg kitmaster).

The fiddle yard has one length of track laid and wired up, but that is all for now.

I have also added some more bits of wood to the underside of the baseboards to protect the wiring, servos and circuit boards during transit, and have purchased wood and bits to build the lighting gantry, but it was just too hot to do much today.

So, at the AGM, there will be plain, unballasted track and no scenery, but quite a lot going on underneath the baseboards, and hopefully trains running (analogue DC and/or DCC).

Ian Morgan.

Another milestone - trains running

This week saw the completion of the track wiring, and the successful test running of trains all over the layout. There was just one missing link wire found. Wiring up the point operating servos is still to be done. From the photos you can see one Merg Servo4 board mounted under the baseboard. Two more of these will be fitted to control the remainder of the points, and the, as yet, non-existant uncoupler magnet devices.



One inovation I have added is to allow instant switchover from analogue DC operation to DCC operation. The rails are divided up into sections, as normal. Individual lengths of rail in a section are linked up by the copper tape runs beneath the layout. The point 'frog' sections are kept as short as posible, and are fed from microswitches operated by the point mechanisms, switching between the two adjacent stock rails. Each rail 'section' is kept separate on the layout, and are fed by wires from a single multipole connector (an old Centronics parallel printer socket with 36 pins.



I then added wire links inside a plug to connect the sections together. For analogue DC, siding sections are linked to 'frog' sections so that they are isolated by the points. Another plug, for DCC operation, would link together all the left-hand rails, and all the right-hand rails, and leave the 'frog' sections unconnected.

SR Buffer Stops

At last, some spare time for modelling this weekend, so I worked on making up the lovely etched buffer stop kits I got from the 2mm Scale Association. I had started one a few weeks ago, but a good day's work today sees completion of all five required by the layout.



These kits make a form of buffer stop I was not familiar with, but I have found a very similar looking one at the eastern end of Ascot station, unfortunately not in easy reach of a camera though.

The beautiful, and cleverly designed etch is in nickel-silver. I really like using this material. The etch folds up, eventually giving 6 layers which all line up accurately for 'sweating' together with the soldering iron. The triangular gussets that attach the front 'leg' to the rail are a bit fiddley to line up and attach though.



I used real wood (recycling a coffee stirrer) for the beams rather than using the 5-layer etched beams provided. It feels more appropriate, and is electrically insulating, but proved tricky to attach using superglue. The tie-bar passing through small drilled holes in the uprights was a bristle from a large brush - also electrically insulating.



It seems my painting skills have lapsed over the long period since I last did any, and my hands seem to be not as steady as they used to be, but applying red and white paint on the ends of cocktail sticks, I managed to straighten up the lines fairly well.

Fresherwater tracklaying completed

A milestone (or is that a millstone?) has been reached. All the track is now laid, except for the buffer stops which will be the eagerly awaited etched SR kits. I have made a start on installing the dropper wires, and one point mechanism and servo is in place, so I have some way to go before proper testing of the track can start.

As can be seen from the non-painted track, there was a lot of curved track required (half track created in the jig, then the second rail being added using triangular gauges once glued in place). I had some shorting sleepers on these stretches which had to be sorted out in-situ and took some time to find and fix. This is one advantage Easitrac has over copper-clad.

I would like to get the wiring done by the end of March, but we have the Basingstoke exhibition using up one weekend (Highbury colliery will be there).

Yet Another Point Tie-Bar Mechanism - 2

Here is how the mechanism described in my previous post is fitted below the baseboard and the point. Remember, the point blades are fitted with operating wires, formed using the Easitrack bending jig, so the point has two vertical operating wires dropping down near the ends of the point blades. Two small slots are drilled and carved in the baseboard surface before gluing the point down. The slots are wide enough to allow the brass tubes from the operating mechanism to pass up through them, with enough sideways throw to allow operation of the point. This photo shows the point in position. When it is ballasted, there should be very little of the mechanism visible, I hope:



The mechanism is glued underneath the point. As it is put into position, the two operating wires dropping down from the point must be threaded into the two tubes of the mechanism. The ends of the tubes will be just below the top surface of the baseboard when located properly. Some rigid brass wire with an omega loop formed in it is hooked into the hole drilled at the end of the PCB in the mechanism. I am using servo mechanisms to operate the points. These are very cheap on Ebay. I have some MERG Servo4 electronic kits to drive them (each board will drive up to 4 servos) and the first of the MERG CBUS kits will be used to control them. More on the electronics will be in a later blog posting. I had hoped to glue the wooden blocks that the servo is mounted on to the baseboards, but the glued joint was not strong enough, so small countersunk screws have had to be added which will have to be covered by the scenery.

Yet Another Point Tie-Bar Mechanism

I purchased an Easitrack point operator and put it together, and I was impressed by the engineering, and how nicely it operated. The problem with it was, though, that my baseboard (being a hollow door) has a very thin surface and only an inch or so overall depth. I could not see how I could fix the mechanism in place, and much of the operating mechanism would be hanging below the baseboard, where it would be easily damaged in transit.

Up to now, I have used moving tiebars (copper clad glass fibre board) operated by relays from below. Although I had found them to be simple to produce, and reasonably reliable, they are a bit disappointing to look at. For Fresherwater, I wanted to try something better. The Easitrack blade wire bending jig provides an answer to my main worry over many solutions in that the wire bends and passes below the stock rails, so the blade tips cannot rise up and get caught while track cleaning. I am still worried that if the solder joint between the wire and the point blade fails, I will not be able to repair it with the track laid, but we will see if that worry is justified.

In designing a new mechanism, I had to take my notable lack of engineering skills into consideration. The mechanism had to operate with large tolerances in almost all measurements. Where I work, tea and coffee comes in pouches which hang from plastic channel 'rails'. Consequently, large numbers of these pieces of plastic end up in the bin each day, so I took it on myself to try to recycle at least some of them.

I started by cutting a length (about 2 inches) and removed some of the side pieces at the ends. It is soft flexible plastic, easily cut with a scalpal. Then I cut two rectangular slots that small brass tubes will pass through, and move lengthwise to operate the point blades. In the photo below, the channel as it comes is on the right, and the cut up piece is on the left:



I then took the L- profile pieces I had cut from the sides and glued them with epoxy resin so that they restricted the size of the channel. These are just visible in the photo. I also glued a small micro-switch in place on a piece of paxolin board:



Next I cut a strip of single sided glass fibre PCB, wide enough to pass smoothly along the inside of the channel. I cut this strip into lengths of about an inch and a half, and made some insulating gaps. I drilled the end for an operating wire, and around the centre for one of the small brass tubes. I left drilling the hole for the second tube, as that is the only critical measurement, and will depend on the point it will be attached to (the way I make them):



To the opposite end from the operating wire hole, I soldered a bent piece of rail with a 12BA nut on the end. The bolt through this nut will operate the microswitch, allowing some final adjustment once in place:





Now I needed a jig to help solder the small brass tubes in place, and here it is - a few pieces of old plywood, and a stiff wire pushed into a drilled hole. The tube sits over the wire and stands vertically while the PCB sits on the top of the ply ends, leaving the right amount of tube protruding below:





So there we are. Having created the first one, I easily made 6 more almost matching ones for the rest of the layout in one evening. How they fit, and work will be revealed in the next installment.

Ian M.

First piece of track laid

There has been a bit of a pause in progress while constructing the track required. As I only have one evening a week to allocate to modelling at the moment, it has taken longer than I would have liked. I also found a new way of slowing up progress by deciding to try filling the insulation cuts in the copper-clad sleepers with milliput (after checking the gaps were actually insulated). With a spray of primer (after washing with Cif and a finger nail brush) they really do look better for being filled.

I also built some MERG servo control boards and a tester/programmer box, as I will be using servos to operate the points and uncoupling magnets. More on these subjects will come later, I hope.

Anyway, the first length of track to be laid is across the board join to the fiddle yard. I am trying out the easytrack brass sleepers for this. Six of these sleepers were soldered in with concrete sleeper profiled copperclad, and the whole lot primed. I had to smooth out my poor carpentry by planing the surface slightly, and digging out a little to cater for the brass sleepers being fractionally thicker than the copperclad ones. The whole length was fixed down with Araldite and weighted down overnight. This morning I have sawn the rails across the gap, and sawn the brass speepers in half to restore insulation between the rails. A little more Milliput filling is required before painting the sleepers, and ballasting.



The photo also shows some foamboard being used as a basis for the river banks. The river is still tidal here, so it will have steep, deep banks.

The first point will be situated just beyond the bridge, so I now have to decide on, and build the operating mechanism, more on that next time.