Monday, 22 May 2017

Latching Fiddle Yard Mechanism - A Prototype

The Sussex Downs 009 group are building a new layout, and discussion at the last meeting came to how we'd build the fiddle yards. The design calls for two turn-tables each with 4 tracks, that are able to quickly change between trains and turn them without handling. This is far from a new idea, the traditional design uses a sliding bolt (as seen on doors and gates) to provide both mechanical alignment and electrical contact to each track. A simple idea that works well enough, but in the smaller scales, the need for precise alignment conflicts with the need for the bolt to slide and engage easily, which can mean they can be stiff or fiddly to use.

I saw an idea posted on a forum some time back that used a pivoted lever with a notch that engaged on metal edges aligned with and underneath the tracks, all that was needed was to depress the lever to release the engagement and move the deck until the next one engaged. The problem was it was bulky and required a lot of space below the deck, which the club layout design didn't allow. I felt the concept was sound though, and after some thought I came up with way that a similar idea could work in much less space, and be constructed with minimal need for accuracy and without special tools or skills.

Ideas are all well and good, but the only way to be sure it works in practice is to try it out. So I raided the garage for leftover bits of wood and PVC foam-board, and with literally no expense spared incurred, built a mock-up over a couple of spare hours at the weekend. The size was dictated by the materials to hand - the deck is about 18" long and 9" wide, long enough to demonstrate it - while construction is somewhat crude. I've added other ideas too like the handle/gate. Now, let me show you the idea...

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An over-view with the deck turned to the front track. On the deck are three pieces of PCB to which tracks would be attached, and through them the top of a brass tube/pin protrudes and is soldered. The handle we’ll come to later. To the left is the release mechanism – push the wooden lever to the left to unlock the deck to turn. The lever was an afterthought "improvement" - initially I just pushed the wing-nut (which could have been a nice wooden knob) to the right, but the lever is nicer to use. I guess that's the point of the mock-up!

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Under the deck you can see a brass “latch” (triangular with a notch at the top) attached to a pivoted lever, the free end of which is moved by the release knob (bolt) - and now the lever too (fitted after I took this photo). The support for the deck is shaped for a particular reason.

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From underneath you can see the three location pins (brass tubes) protruding down through the deck, and the latch arm locking mechanism which pivots on the lower wooden block, the other end slides on the upper wooden block.

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The latch arm close up, the bottom is the pivot, the top rotates as per the arrows, and is pushed by the bottom of the wooden lever. The high-tech tension device (rubber band in this mock-up, but a spring would be better!) pulls on back the latch arm. The bass latch can be seen with a wire from it, and against one of the slopes a location pin can be seen from the deck. As the deck is rotated this slides up the brass latch by pushing against the lever until it drops into the vee shaped notch, holding it securely and making electrical contact between the brass latch and the PCB above.

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The location pins only protrude about 5 mm below the deck so clear the frame of the board – the foamboard is 5 mm thick - and at the top, protrude just far enough to be soldered to the PCB, and not foul locos passing over them. The rest of the mechanism is contained within the frame. This makes it reasonably straightforward to build this mechanism, and contain it within a conventional design and depth of baseboard.

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Back to the handle. In the up position the tracks are clear, but when pushed right over the bottom of the handle uprights contact the supporting board below stopping excess movement. With the handle folded down the deck is free to rotate beyond the last track – i.e. can turn right around - as seen here.

Operation is simple: simply push the lever  to disengage the pin and rotate the deck, once the lever is released the deck latches at the next track that it aligns with. As the brass pins are round, and the notch is vee shaped (with rounded entry), alignment is actually very precise - as the pin reliably self-centres in the vee. No effort is required by the user to achieve this, the deck is simply rotated until the pin clicks into place. Electrical contact is also made connecting the aligned PCB (i.e. table track) to the fixed track.

This system would be just as useful on a traverser or sector plate as a turn-table, and had I thought of it a couple of years back, I'd have used it on my "exhibition" fiddle yard for Awngate instead of the micro-switches. Some of the construction details could be improved from my quick mock-up, but overall I'm happy to say the concept works well.

Wednesday, 10 May 2017

Decoding the Wiring Enigma

I don't do a wiring diagram, but I do plan out the wiring before I start. The key is the track plan, with track feeds marked, and a "code" given to each feed, point, and indeed each wire. The wires are connected from switches to track and point motors, via terminal blocks, following the codes to label each wire.

Hexworthy has just four points, I've labelled A to D. Each has a feed to it's frog (in this case, the wire dropper from the PECO points) which is switched by the point motor, and I've labelled them Af, Bf, etc. There are 5 switched track sections labelled 1-5, I put the feed into the rear rail (as the wire is less visible) and only gap that rail, so fewer "common return" feeds (labelled R) are required. Because of the live frog points breaks are required in both rails of both joins between the red and green sections.

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The switch wiring schedule is pretty straightforward, the table above shows the wire codes for the input and output of each switch. "T" is the controller track output, and "P" is the point motor power from the capacitor discharge unit (CDU). Note that the sections may be fed from the adjacent track, so for example section 5 is only live if section 4 is switched on and point C is set to the siding, as well as switch 5 being on.

Wiring to and from the switches is via screw terminal blocks that make the wiring easier to follow, make joining wires easier, and providing a point to de-bug if needed. There are terminal blocks for the incoming power supplies (from a 6-pin DIN socket), the connections to the panel, and as shown previously - one for each point motor which includes the frog switching as well as the motor connections. From the track plan it can be seen which rails are being switched, so the inputs come from the section, return, or previous frog feed - this saves extra wires to the rails. Example terminal block connections are shown above, the colours indicate the wire colour used.

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This is the result with all the wiring in place - surprisingly complex for such a simple track plan! At the top of the picture the control panel is lifted out to access the switches at the rear, below it the terminal block feeding the switches can be seen. On the right are the connections to the power socket, note that the return wires are linked over two terminals to make room for multiple connections. Below and left can be seen two of the point motor connections. All terminals are labelled with the wire code denoting the connection to switch, point motor, or track, so wiring up is simply joining the dots.

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The other end of the board is a little less busy. All that remains is to tidy the cables, bundling together with tie wraps or a twist of wire, and securing where necessary.

You can see I've cut a slot in the foam-core, that's a hand-hole. I was finding it difficult to find places to grip when moving the layout around!

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Up top the markings for the feed wires can be seen - and if you look closely, the wires can be seen soldered to the rails. I feed the wire through a hole in the board and form the end into a "7" shape, tin the end, and hold it against the rail web while pressing a soldering iron against it until the solder flows - hopefully giving a neat and secure join.

The loco is on a test run. I'm pleased to report it all worked first time! The careful planning has paid off.

Monday, 8 May 2017

Panel Games

Before wiring can commence I needed to finish the control panel, which had been mounted into the front fascia of the baseboard. The schematic is laid out on the computer - I use Word, which has simple drawing tools that allows objects to be drawn to a measured size so the printed size is known. The drawing is duplicated, one has the switches drawn in place - ensuring there is space between them, and marking the centres. This print-out is stuck on the aluminium panel, and the centres of the switches punched.

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I then took the panel into work and used a pillar drill for the switch holes, and not forgetting the screw holes in each corner. These took a bit of cleaning up with various files.

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On the back of the panel I also drilled a small hole part-way through above each hole, this is to locate the tab on the keyed washer that stops the switch from rotating. The second print-out (without the switches drawn on) is cut to fit, including switch holes, as is a piece of clear plastic. I used a piece of packaging, but anything clear, stiff, and about 10 thou thick will do. The switches are mounted through the three layers.

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With the panel screwed in place the result is a neat, easy to follow panel for surprisingly little effort. Recessing the panel means the edge of the plastic and paper layers aren't seen or vulnerable. I've added coloured rubber grips to the section switches to match the diagram, while point motor switches are left silver.

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Wednesday, 3 May 2017

Fitting Point Motors

I gave some thought as to which point motors to use. Slow-acting motors have become popular, and we're using Tortoise motors on the latest club layout, which seem well designed and made. However they are very deep, and even the 3.5" depth of the Hexworthy base-board is insufficient, so they don't suit shelf layouts. They are also pricey, and I've heard mixed reviews of cheaper versions, even though I only need four I find it tricky to justify £10-20 per point. The thing is, I don't really see the need for slow acting motors - whenever I've seen a real point move it's with a "clang" that takes less than a second. OK, so solenoids go faster and with a "Thunk", is that worse than a 2-3 second "whrrrrrr"? It's never bothered me...

Servos have started to become popular in recent years. They are cheap, but need a mounting arrangement, and a circuit to drive them - while there are various options for this (including from PECO) they do push the cost up and they aren't simple. I've also heard reports of them "jittering" or moving due to voltage spikes or noise from motors.

Solenoids are relatively cheap, reliable, and simple. My choice are SEEP motors, they are easy to fit under the baseboard with no extra fittings, and have the necessary built in switch for frog polarity switching. Those on Awngate were salvaged from a previous layout and so are probably over 20 years old, I admit they're not used intensively but I've only ever had one failure - and that was repaired. I already have the Capacitor Discharge Unit (CDU) in my power-pack to drive them, and a simple passing contact switch or push button is all that's needed to operate them.

The one problem I have had is that the motor requires enough movement to switch the switch properly, but on Awngate with a 6mm baseboard the movement of the 009 point tie-bar was barely enough, requiring some careful set-up. It struck me that the motor can travel further than the tie bar as the pin invariably flexes a little, so if the motor was further from the point the excess movement could be increased, and the need to site the motor perfectly would be reduced.

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Firstly a ruler was set along the tie-bar and a pin pushed through the foam an inch or two from either end. Underneath the board the pin holes were joined with a pencil line marking the line of the tie-bar, the point motor should align with this to work effectively. Next the hole for the actuator pin was opened up from below with a scalpel, wider at the underside than above, ensuring the pin cannot foul on the foam-core (which is double-thickness, so 10mm deep here) even if the motor travels further than the point tie-bar. The hole was later painted black. Note the wire in the centre of the picture, which is the dropper from the point crossing vee/frog.

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Previously I've glued the SEEP point motor base directly to the underside of the baseboard. I figured it would make them easier to change in the event of a failure if they were screwed in place, so I made some mounts from 9 mm ply. The big hole clears the actuator pin and the motor is attached with a couple of small screws, a couple of pencil lines mark the centre-lines. You'll note the motor is now about 19 mm below the point.

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From above the points were wedged to the centre position with a couple of strips of plastic behind each blade, I think they were about 30 thou but it was whatever fitted. The blu-tak holds the wedges while I invert the baseboard.

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The motors were held centrally by a piece of plastic cut to fit between the coils, and a hole for the pin. The pin was pushed into the tie-bar hole and the ply stuck in place (PVA is fine), aligning the centre-lines as it sets. After the glue is dry the plastic pieces are removed, the excess pin is marked, the screws were removed to release the motor, and the pin cut down. They're tough steel so a slitting disc in a mini-drill is best for the job.

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While the motors were out I soldered wire tails to the contacts - much easier on the bench. I've added these the same to all the motors, long enough to reach a 6-way terminal block connector, which you will note is sited so that the wire dropper from the point frog connects straight in. The grey wire is the switched (frog) output, the white pair are for the stock rails, the green pair are the switched motor feeds to the solenoids, and the black is the return from the solenoids.

In theory I'll be able to change a motor with 8 screws - two holding it, and 6 wires - provided it has the same length pin and wires pre-attached, so I may prepare a spare for exhibitions. Now though I need to finish the wiring and check they all work.

Sunday, 30 April 2017

Historic Futuristic Travel

Looking for an interesting day out with the kids over the Easter break I spotted an offer with Hovertravel for cheap day returns to the Isle of Wight. Now I think Hovercraft are a pretty fascinating form of transport - technically, they are flying rather than sailing - and there isn't anywhere else you can ride one as a scheduled passenger service.

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Hovertravel run a service connecting Southsea (with a big car-park) to Ryde in just 10 minutes, which is used by a lot of commuters in both directions. How about that for a journey to work? They are, I think, quite majestic as they roar across the see, swoosh over sand, shingle, and concrete, and relax onto the ground with a sigh of the engines. Quick, and quite civilised, if a little noisy!

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It seems a futuristic way to travel except that they've been around since the late 1950's and don't seem to have caught on more widely, the cross-channel service stopped in 2000 and the craft we travelled on is around 30 years old. Hovertravel see a future though, having invested in new Hovercraft built in Southampton, but sadly the new arrival seems to be sitting in disgrace, with transmission trouble.

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I do hope it's sorted and secures a future for Hovercraft, but while the new model looks more sleek, I think I prefer the old one - it has more windows, and what use is travelling so fast if you can't see that you are?

The Isle of Wight has figured out integrated transport. Outside the hover terminal is the railway station - which continues down the pier to connect with the newer but slower catamaran service - and the bus station. We chose the train, which runs a frequent and reasonably priced service down to Shanklin over electrified lines. That sounds modern and efficient, but visitors may be surprised by the train they find...

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Yes, that's an underground train. In fact it's a 1938 London Underground train - which, if you think about it, makes it older than most of the carriages seen on preserved railways across the UK. And yet this is part of Britain's national rail network, operated by SouthWest Trains! By some quirks of history a small fleet of these trains have been found ideal to run this short line, making for an interesting journey with the varnished wood and springy seats inside. Mind you the seats need to be soft as the ride at 40+mph is quite alarming, bouncing and swaying quite violently. As the guard (yes, they still have them) commented, it's as good as any fairground ride.

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So, a day out to the Isle of Wight. We went back in time and travelled into the future.

Saturday, 22 April 2017

Two shows in one day

I was rather spoilt for choice today, with several shows within striking distance, but I couldn't visit all of them. I did work out that I could make time for two if they were in the same direction, so I started with a long trip up to the M25 to the 7mm NG Association Surrey Group show in Merstham.

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It was nice to see Cranbrook Town again after a good few years, it has real character that has survived several changes of ownership and is now owned by Paul Davies.

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Totherend (Roger Jones) was new to me, with a quirky layout and working standard-gauge wagon transporters it offers something a little different. Nice locos too.

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Morton Stanley was recently featured in Railway Modeller, and shows how an interesting layout in this scale need not take up great space or expense. It may be the last time I see it though, as builders Chris Ford and Nigel Hill have it up for sale - if you are interested!

These, along with most of the 11 layouts were O-16.5. More photos from the event can be found here. There was also the 7mm NGA sales stand and a few specialist traders, plus some familiar faces to catch up with.

A short while later I was at the Crawley MRS exhibition - confusingly, in Horsham. This is one of the larger club shows and has a good number of layouts and traders, and was of more interest to my son. And I always find something I need at the Squires stand. Now I do find many of the traditional club layouts (big ovals with a station) a bit, well, lacking in interest to be honest, but there were some layouts that caught my eye.

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Narrow Gauge is always of interest and Theobald’s yard (Orpington and District Model Railway Society) mixes 7mm SG with 16.5mm gauge with some remarkable track-work and quirky trains.

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The World's End is a well-known OO layout with some superb buildings and scenic work. OK, the trains just trundle through, though they are prototypical, but it is the modelling that makes the layout worth studying.

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More modelling worth studying was found on Newhurst, a 7mm SG layout. Oh, the trains were nice too, but the scenery made it stand out.

More photos from Horsham here.

Thursday, 20 April 2017

Track Down

Over the weekend I'd popped over to Gaugemaster to buy some track. Since my last few 009 layouts had used "recycled" points from an earlier layout it's many years since I bought track - and I have to confess I was surprised how much four points and three yards of track (the new "mainline" 009 type) costs! Anyway, time off this week means a chance to lay the track, between playing with the kids.

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Track laying started at the join to the fiddle yard - which I connected with the split hinges. A piece of copper-clad PCB was stuck firmly down and the rails soldered to it aligned to the FY track.

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Tools of the job. I use Xuron track cutters which are quick, quiet, and clean. Do watch for flying off-cuts though, and a file is used to clean up the end of the rail so a fish-plate fits. A razor saw is useful to mark the rails where to cut them with  the cutters, the scalpel is for trimming or separating sleepers, or opening up the chair to take a fish-plate. It's also used to cut holes in the foam-core board. The 12" radius tracksetta is a useful guide that curves are no sharper, though there are few curves on this layout, for bits that should be straight a steel ruler along the rail is a useful check.

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Track is glued down but first all the pieces are cut to size and laid "dry", held in place with track-pins beside the rails and sleepers - this is enough to hold the curves and position. You can just see the pins either side of the curves here. These pins are Gaugemaster or Hornby and are reasonably chunky - not the flimsy Peco ones. Track laying starts with the "main" line and loop, with sidings positioned later. Much time was spent carefully checking and adjusting the position of the points and curves so there is sufficient clearance, the loop is just long enough for 3 Peco L&B coaches (not that all trains will be that long), while at 5 inches the release should take any loco I anticipate.

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With the track cut and positioned holes were cut for point motor actuator rods, and for the point vee/frog wire that comes pre-attached to these new Peco points. The track was then inverted and PVA glue run along under the rails (keeping clear of moving point parts), then carefully positioned on the marks and between the pins, being weighted down (tins of beans did the job) while the glue sets. The pins can then be removed.

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While most of the track is the neater "mainline" style, the front siding uses the older "crazy" irregular track for an older less well-kept effect.

Track feeds (arrows) and rail gaps (orange lines) were marked out before sticking the track down. Where gaps were at a join - such as at the loop release point - insulating rail joiners were used. However where gaps fall in plain track I prefer to cut them later.

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I used to use a slitting disc, but having found these useful disc saws at Squires I've found that, with practice, they can make a neater cut, and with less risk of shattering. I'll probably run some epoxy glue into the gap at some point to make sure it doesn't close up if it gets warm.

Monday, 17 April 2017

A Visit to the Lavender Line, and a Visitor to the Bluebell Railway

Looking for a day out on a bank holiday we decided to visit the Lavender Line at Isfield, near Uckfield. This is a small preservation group with a nicely restored station and about a mile of track. though normally they only run on Sundays, which is rarely convenient for us.

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Trains were running every half hour, alternating between steam and diesel. The steam was this nice Bagnall, towing a single trailer car from a DMU. It looked an odd combination, but since there is no run-round loop trains are propelled back to the station with the guard in the front cab, with brake and horn to hand.

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Diesel duties were handled by a "Thumper" DEMU.

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Other stock was an ecclectic mix with some small Diesel shunters, coaches and multiple unit trailer carriages in various states of repair, a selection of wagons, and this unusual Wickham railcar from British Rail Research.

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The train ride out and back only takes about 20 minutes, but a ticket allows multiple rides (so we tried both trains), and the kids rode the miniature railway too, so we were occupied for a couple of hours. It's a very welcoming place, with kids invited onto the footplate to get close to the controls, though my daughter was rather wary of the big fire!

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Just a few miles along the road the Bluebell Railway is a much better known line, and this week has perhaps the most famous loco of them all visiting - The Flying Scotsman. We hadn't planned to visit but we happened to be passing... though the price of a platform ticket was more than a day rover ticket on the Lavender Line! Still, my Son wanted to see his favourite loco, and it turned out hundreds of other's hadn't been put off either.

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So we got up close, but decent photograph opportunities from the crowded platform were pretty limited. It didn't help that it's train was two coaches longer than the platform, and it entered the station tender first.

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In fact we found the most dramatic views were from the picnic area below the line, where we got a good view of it departing.

Saturday, 15 April 2017

Baseboard Finishing Touches

Hexworthy will need a control panel, and like Awngate, the best place seemed to be the front fascia. The layout will sit on a shelf and be front operated, and the fiddle yard adjoins the end, so other than the hassle of a separate control box, it's the only logical place. The panel is a scrap of 2mm aluminium from the guillotine at work, which happens to be an ideal size, but normally I'd fit it to the rear of the fascia for neatness. Here though there wouldn't be space for it to be removed from behind for access to the switches, so it had to go in from the front - so to maintain a neat appearance I decided to recess it into the fascia.

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Here's my piece of aluminium, with some trial printouts of the panel layout. These aren't yet final, but show it will all fit. The fascia (bottom) has had a suitable sized hole cut out, with two other layers cut too, one to the size of the panel, and one a little smaller.

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The two layers are glued behind the fascia creating a 6mm deep recess which the panel just fits, and a support which it will eventually be screwed to. These two layers also reinforce the thin ply edges so this is not a weak point. Meanwhile, the foam-core board is cut away with a knife to make space.

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Fitting it together, you can see how the foam-core structure and the timber reinforcement conspire to make access from the rear so tricky. I've also added a socket for the power connections at the same time.

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All fitted together. I need to drill the panel for the holding screws, when I drill it for the switches too. I've also cut and fitted the "wings" that frame the sides of the scene, and hide the untidy bits like split hinges and back-scene framing.

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Talking of the back-scene, I've used some offcuts of the thin timber strip to brace it. These are screwed to the lower reinforcement, glued to the ply back-scene, and stapled through from the front. The ply back-scene is much stiffer now, with no tendency to bow.

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So there we have it, one tidy looking, solid, yet surprisingly lightweight base-board. I do need to add a lighing beam - when I've decided what lighting to use - but for now I can proceed to track-laying!

Friday, 14 April 2017

The Baseboard Core

Phase 2 of the baseboard construction involved 5mm foam-core board, this is the stuff made with expanded polystyrene sheet between two layers of thin card. It's easy to cut with a knife and can be glued with PVA, or more quickly and strongly with a hot glue gun, making baseboard construction easy and flexible - and relatively quick. I've used the technique for Pen-Y-Bryn Quarry and more recently Thakeham Tiles, with the former I learned it is easily damaged so needs a protective layer, with the latter I clad it in 3mm ply which worked well. Hexworthy is a much bigger board, and the need to connect it to an existing fiddle yard led me to make the outer ply "skin" first and make the foam-board core to fit. Actually this is probably a harder way to do it...

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The first task was to mark out the "deck" including transferring the track plan from the paper plan, which was done with the highly technical method of using pins...

Now I forgot to photograph the construction phase, but it was pretty similar to that of building the board for Thakeham. Here I doubled the thickness of the foam-board under the track, not because I think it needed the strength, but to increase twist resistance and to enable cuts (e.g. drainage ditches) to be added to the top surface later. Bracing was cut and glued to the underside at about 9" intervals, interlocking where longitudinal and cross bracing met, like an egg-box. Some diagonal bracing was added too.

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A complication was the river along the front, which is set about 1" lower than the track bed, polystyrene sheet was glued in the gap to firmly join the two layers and will be cut to form the river-bank in due course. There's also a stream under the tracks, which has yet to be fully cut out but the base is ready underneath. The front will have a thin ply fascia, though this has yet to be cut and fitted, and there will be "wings" at each end which will help stiffen the end boards.

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Underneath the bracing can be seen. Due to the length of the board I was concerned about flex or twisting, so I decided to box in the rear part of the frame to make a "torsion-resistant" beam. There's little track over this part, and if I need access to wires etc I can cut access holes. Once the board was glued into the ply outer shell (with PVA) it turned out to be surprisingly stiff. The strip-wood runners along the base are more to protect the foam and bear the weight onto the supports, than to add strength.

The resulting board seems pretty strong, there's no bending and no end-to-end twist unless significant force is used. There's a little flex in the back-scene, which is unlikely to be an issue but I plan a couple of diagonal braces. It's certainly easy to move about on my own despite it's length, at around 4 kg I think. Hopefully I'll get it finished over Easter, and maybe even buy some track...