Sunday, 2 December 2012

Magnetic Couplings - Important Information

IMPORTANT INFORMATION

One of the best ways to kill a good idea is to not define standards early on, so that everyone does it slightly differently, and no two systems can work together. Examples include VHS & Betamax, mobile phone chargers, and many more. There is one critical parameter of the McBogle (also known as DOGRF) Mk.2 coupling that I haven't yet defined and will now attempt to do so. For two couplings to mate correctly, they must both have their N and S poles in the same orientation, so that on mating, N attracts S and S attracts N. Having made about a dozen of these couplings now to an arbitrary standard, I have measured which are the N and S poles and will define this as the McBogle Mk.2 magnetic coupling standard. In that way, any couplings you make should work with anyone else's, and vice versa.

The tools you need are an ordinary magnetic compass (and no, a GPS receiver won't work unless it includes a magnetic compass), and a bar magnet (one of the magnets you are using for the coupling will do). Glue your magnet to the end of a non-magnetic stick with the line between N and S in line with the stick. (If you are using the same magnets I did, then one of the two flat faces is glued to the end of the stick.)

Point the magnet end of the stick at the compass, and move it all the way round the compass. If the red (N) end of the compass needle points to your stick, then we will say that your stick ends in a N pole. (I'm not sure whether this is the normal convention, but that doesn't matter provided that everybody follows the method exactly as I have described it.) If the red (N) end of the compass needle points away from your stick, then your stick ends in a S pole. Mark your stick with either S or N at the magnet end, and the opposite at the other end. You can now use the magnet end of your stick to check the polarity of any coupling or magnet, bearing in mind that N and S are attracted, and N and N or S and S are repelled. Couplings can also be checked by ensuring they mate correctly with a known good one. A known good one can also be used to hold a new pair of magnets in position while they are glued to their "pipes". I will try to add some photos to make this clearer.

And which way round should the coupling magnets be? When looking at the end of a vehicle on the rails with a coupling fitted, the mating face of the right-hand coupling magnet should have its N pole toward you.

Finally, a VERY IMPORTANT SAFETY WARNING. If you bought your magnets from a reputable dealer, you will have been given some dire warnings. It is worth reiterating that these tiny magnets can cause life-threatening injuries if accidentally swallowed. So keep them in their original packaging until assembled, and don't leave them laying on the work bench. And don't fit them to anything that could be used by children. If you pass them to anyone else, also pass on the warnings too. It's all common sense really, but so easy to forget or ignore, with potentially serious consequences.

Friday, 30 November 2012

Magnetic Coupling Trials

I spent a couple of hours today, despite the freezing weather, preparing a length of garden track and running a 12-coach test train round the reverse curves on a 1 in 50 gradient. This was the first fully "live" trial of the "McBogle (or DOGRF) Magnetic Coupling" (see previous post). The couplings between coaches 1, 2, 3, 4, 5 and 6 were to the Mk.1 design using a single 3mm x 2mm magnet on each coupling. The couplings between the loco and the first coach, which were taking the greatest load, were Mk.2, with an opposite-polarity pair of 2mm x 2mm magnets. None of the couplings failed during the trials, which comprised several low-speed runs up and down the test track. (Higher speeds were not possible this time because of undiagnosed limitations in the control or  power distribution equipment, i.e. it couldn't supply enough current for a Hornby class 50 pulling 12 coaches up 1 in 50 at more than a scale 20mph.)







Conclusions
  1. Both the Mk.1 and the Mk.2 magnetic couplings have a more than adequate holding force for a 12-coach train of 160g coaches on a 1 in 50 gradient with reverse curves of radius 4ft and greater. Tests were carried out at scale speeds of 20mph and lower.
  2. The Mk.2 is easier to use, as identical couplings wll mate with each other. Before the start of the trial it was necessary to change the Mk.1 couplings between the loco and first coach for Mk.2 because one of the Mk.1s was the wrong polarity.
  3. Further tests are needed to assess the long-term reliability of the adhesive joint holding the magnet to the "pipe", with the stress of regular coupling and uncoupling.
  4. (Not related to couplings.) An unexplained gap between two lengths of track on a reverse curve has now grown to about 5mm (it was about 3mm in the summer). It is now causing regular derailment and needs investigating.
  5. (Not related to couplings.) A rail joiner near the top of Quarry Bank has no wire jumper and is not making good contact.

Thursday, 29 November 2012

Magnetic couplings.

An important decision that all railway modellers must make is which types of coupling to use between vehicles. There can be many factors affecting the decision; cost, time, realism, ease of coupling and uncoupling, .....

For my own set of priorities, I came up with the following guidelines:
  • Front of locos to be as realistic as possible, with all pipes, and hook-and-screw-link coupling.
  • Rear of locos to be as realistic as possible, while retaining a working hook-and-chain coupling and an NEM pocket to allow fitting of a coach-compatible coupling.
  • Pre-1970ish freight stock to have working chain-and-hook or instanter couplings
  • Passenger stock to be as close-coupled as possible, but I hadn't found the ideal system.
The locos and freight stock were therefore largely properly equipped, but the passenger coaches were fitted with a selection of couplings including all variants of the industry-standard "Triang" tension-link couplings (both NEM-fitted and non-NEM), Hornby/Seuthe close couplers, and the recent Bachmann "Vacuum-pipe" fixed close couplings. Interchangeability was achieved with some difficulty by retaining a selection of spares of each type and moving them around the NEM-pocketed coaches as necessary. Others had been tried and rejected.

A thread appeared recently in the "00 Garden Railways" forum entitled "Bachmann Coaches - Close Coupling System". This referred to an article in issue 204 of "Traction" magazine proposing the use of high-strength Neodymium magnets to make the Bachmann "Vacuum-pipe" couplings more readily seperable, and describing the writer's own experiments with the technique. For me, this sounded ideal for the coaches; all the advantages of the Bachmann "pipes", without the need to invert the entire train to uncouple!

I had previously carried out tests and calculations to establish the force required to pull trains up the 1 in 50 gradients on my railway, which showed that the horizontal force required from the locomotive for 12 coaches of average weight 150g up a 1 in 50 gradient is about 46g. This is beyond most RTR 00 steam locos, but for modern RTR diesels it is no problem. Using 2mm dia x 2mm Neodymium magnets from Magnet Expert, I lifted gradually increasing weights, and 55g was the highest that held reliably. This was with a sheet of gummed paper between the magnets to attach one to the weights, while the other was glued to the end of a shunter's pole.

So with a straight pull, 12 coaches up 1 in 50 is feasible. In practice, there will be misalignment, shear forces, and shock loads to contend with, so a stronger magnet would be desirable. But it was close enough that I resolved to carry out further experiments.

I acquired some 3mm dia x 2mm neodymium magnets with a specified 250g in-line parting force and 50g shear parting force. I found some 4mm heatshrink tubing and some Loctite 406 adhesive (for plastic & rubber), and bodged together a pair of magnetic couplers. They were badly made, and the magnets didn't make good face-to-face contact, but I tried them anyway. One went on a loco, the other on a coach, and they were coupled together. The other end of the coach had a cord attached, which ran over a pulley to a hanging weight tray. The weight was increased up to 87g, which is equivalent to pulling 25 150g coaches up a 1 in 50 gradient. I shook the coach and the weights to give a bit of shock loading, and still the magnets held.

I was now more than confident that the technique would work with plenty in reserve, providing I could find a successful method of attaching the magnet to the remainder of the coupling, which would hold when the couplings are repeatedly pulled apart to separate the coaches. The following technique seems to work. I first glue the magnet and pipe together using fast-acting cyanoacrylate adhesive, followed when that is dry with something thicker and more reslient such as Loctite 480. When that has cured, I slide a 5mm length of 3mm ID 3:1 heatshrink sleeve over the joint. Shrink the sleeve, squeeze in a little superglue, and hey presto! It's done! There's a picture below of a pair of coaches coupled up.
 
 

I measured the pull-apart force of a randomly-selected pair of couplings fitted to a loco and a coach. At 180g, it was still holding. That's equivalent to about 56 coaches up a slope of 1 in 50, and is much more than any of my locos could pull, quite apart from any other considerations!
 
There is one other minor matter to consider when making and using these couplings. To have a pair of magnets attracting each other, one must have the N pole of the magnet outward from the coach end, and the other must have the S pole outward. So we need to make equal numbers of each type of coupling (which will happen automatically if made in joined pairs), and make sure they are fitted in the appropriate places. Those who wants their coaches in a certain order in the train and pointing in a certain direction, may need to swap round some of the couplings to remarshall a train. Maybe not a problem, depending on how you use your coaches.
 
To resolve this N/S pole issue, I tried a variation on the design using two smaller magnets (2mm dia x 2mm) of opposite polarities side by side. In this way, the couplings at each end of a vehicle are identical, so the vehicles can be coupled in any orientation without changing couplings. I've tested a pair of double-magnet couplings, and they were still holding strongly at a pull-apart force of 190g! That's almost twice what my strongest loco can pull before the wheels start to slip. (Note that 190g is the horizontal force in line with the loco, or the weight it could lift or support using a horizontal cord running over a pulley. It is not the total weight of the train it could pull, which is much greater.) I'll post a full report when I have some pictures.

The advantages of this design (which I have designated Mk.2) over the single-magnet version (Mk.1)are:

- All couplings are identical and interchangeable
- Smaller magnets - looks neater in side view

I have also devised a simple production method which automatically holds the pairs of magnets in exactly the right orientation for assembly, without the need for any special jigs. Again, a report will follow when I have some pictures.

Further developments? Well, a better design variant is still needed for fitting to locos, and for use on vehicles without an NEM pocket. And it's possible that an even smaller magnet (2mm dia x 1mm) would still give enough strength for our purposes, while still retaining Mk.2 compatibility but requiring less force to pull apart. Watch this space!

Monday, 19 November 2012

... and In the Open

A few engines have been in the workshop recently for painting, weathering, numbering, detailing, performance optimisation, etc. The two closest to completion needed a test run on a longer track than I have indoors, so here they are!

The "Standard 5" 73054 has been modelled on photographs taken on the day she hauled me (and others) from Evercreech Junction to Bournemouth (West) (see previous post). She still has a few jobs awaiting, including fitting the front steps.

The diesel unit, known as a "class 121", has just been fitted with new wheels, as the flanges on the original wheels were so deep that they rattled along the rail chairs.

BR standard class 5 4-6-0 no. 73054 runs down the railway straight.

73054 further along the railway straight.

A diesel unit, cascaded from Paddington suburban services, on the quarry bank.

Friday, 16 November 2012

In the Paint Shop

I have spent a few hours this week working on nice, shiny, ex-works model engines and making them look scruffy. Am I going mad? Well, maybe, but my excuse is that this is how they really looked in service. Take the example pictured below. This sticks in my memory (assisted by my photographic records) as the engine that pulled me and some friends from Evercreech Junction to Bournemouth West on 27th March 1965. What made this engine memorable was that it was exceptionally clean and shiny, and it had a multi-tone "chime" whistle. However, looking now at the pictures taken that day, although most of the green paintwork had been cleaned, the rest of the engine still had a thick coating of grime and rust.

73054 on the work-bench during detailing and "weathering".


73054 at Evercreech Junction, 27/3/1965.

Saturday, 3 November 2012

Trials

Today the weather was reasonably dry, the railway was covered in leaves that needed removing before they turned into compost, and I needed some fresh air and exercise. I also had a few things to test on the garden railway which couldn't be done with the facilities I have indoors.
  • Move the wi-fi network extender to the summer-house and use it as a local-only network with a stronger signal everywhere on the railway.
  • Try out an old ipod given to me to use as a second walk-about controller with WiThrottle.
  • See how well Tornado performs after modifications to improve on its original 3 coach limit up the 1 in 50.
The trials were all successful. A train can now be controlled from anywhere on the railway, with no dead spots. The ipod controlled trains - for five minutes after which the battery gave up. At least I now know it's worth considering whether to spend the £59 needed to fit a new battery. And Tornado romped up the 1 in 50 quarry bank with eight coaches.

Tornado romps up the Quarry Bank, watched by the local wild-life.

Tornado, about to enter the tunnel. (Photo with permission of the railway authorities.)
As can be seen from the first picture, the trackside ground-cover plants are doing reasonably well - especially since some of them were not planted until the end of the summer. The fourth green patch from the camera is the most interesting; it's self-set moss, and it seems to be spreading nicely.

Having said that Tornado managed 8 coaches up the 1 in 50; it did twice, then the air suddenly got colder and damper as dusk approached, and from then on the engine started to slip as soon as it got a couple of coaches onto the bank, even when I reduced the train to 7 coaches. I can only assume that a thin film of water was condensing from the air onto the cold rails, and reducing the adhesion. Bachmann don't yet fit their engines with working sanders!

Thursday, 27 September 2012

Double-Heading.

It's an afternoon in early September, and everything is quiet at the lineside above Stoke Gurney. Suddenly, the silence is broken by the sound of a train appearing out of a cutting, its two locomotives working hard against the stiff 1 in 50 gradient. This is one of the last holiday trains of the season, bringing families from the midlands to south coast resorts. The sound reaches a crescendo as the train crosses the viaduct and whistles a warning for the short cutting to the quarry siding.

A double-headed holiday train climbs the 1 in 50 over the viaduct.
 
After a stretch of level track through the station, the two locos dig their heels in again for the final 1 in 50 climb past the quarry to the tunnel and the summit.



The two engines thunder up the quarry bank with their train.
 
As the train passes, the loco crews can be seen on their footplates, the fireman of the pilot engine still working hard to maintain a good head of steam. His work is nearly over though; after the tunnel, it's mainly downhill until they reach their destination.

The fireman of the pilot engine is working hard to keep a good fire
 
Another burst on the whistle , and the train disappears into the tunnel. Silence returns to the valley.
 
 ----------------
 
In reality, this was a test of some new facilities on the garden railway. The name Stoke Gurney was made up as I wrote, and will probably never be used again. The two engines did pull the train up the bank however, as can be seen at http://www.youtube.com/watch?v=ERe_CYS_4Tw&feature=youtube_gdata.
 
My reasons for the running session were:
 
  • To try the DCC controller in the garden after receiving a replacement power supply unit.
  • To test on something longer than the workbench test track these two ancient engines after fitting DCC decoders. The train engine was an Airfix model, bought by my father in the 1970s or early 80s. The pilot engine was a Hornby model bought through ebay as a wreck, the necessary repairs including new cab steps and a replacement mechanism salvaged from another Airfix 4F.
  • To try double-heading with DCC control and its new power supply. I didn't mess around with "consisting"; the two engines were driven with two independent "throttles" on a single ipad screen using the "iThrottle" application.
  • .. and while I was at it, to enjoy the sight of the train snaking up the reverse curves, over the viaduct, and through the tunnel, and record it for future reference.
     
 
 


Friday, 14 September 2012

Track Construction for a 00 Garden Railway.

(DRAFT)

 

Overview

 
General approach: Concrete or brick or building blocks, then a layer of rubbercrete, then roofing felt primer, then 3mm closed-cell foam, then peco flexible track pinned down on curves, then stone ballast held in place with diluted waterproof PVA and enclosing the foam. The straight section up to the tunnel misses out the rubbercrete as pinning was not thought necessary. I have tried other types of ballast and they don’t work and are waiting to be re-done. A of the early ballast, which was not stone, or was fixed with too weak a mix of PVA, came away over the winter. This year, I have been using Pledge "Klear" floor polish instead of the diluted PVA, and it seems so far to have worked. 
 
Not the only way to do it, and probably not the best, but it’s a starting point.

 

Rubbercrete

 
I derived the rubbercrete recipe by trial and error:
  • 1 part by vol ordinary portland cement
  • 0.5 part fine sand
  • 2.5 part rubber granules
  • 0.2 part SBR
  • water to taste

Don’t make too much at once as it goes off in about 5 min. Lay it as accurately as possible; my latest section uses plasticine as shuttering. The tunnel is rubbercrete in cut gutter down-pipe.
 
I got my rubber from http://www.artificialgrass.org.uk/shop/product_details.asp?xp=24 but I’m sure there are other suppliers. If you can find cork granules too (I couldn’t) it might make a better mix. Yes, that’s the SBR http://www.antel-uk.co.uk/tds/sbr-waterproof-bonding-agent.html?gclid=CIWr8pmOmrACFUUhtAodBi7QZw. I got it from B&Q.


Track base and Ballast


I use closed-cell foam as the final track base. It's similar to the material used for camping sleep-mats, and is sold by Exactoscale. I have used several methods of sticking it down. I started by using roofing-felt adhesive. It works well but is messy. I then tried using the roofing-felt adhesive primer only, but this is also messy. (The problem is that you really need to lay the track while the adhesive is still wet, to keep the base as level as possible. Inevitably the adhesive gets all over your hands, particularly if you are forming flexitrack into curves!) For my most recent length of track, I used builder's waterproof PVA adhesive, but it hasn't been down long enough yet for me to be able to say whether it's a success.

Other materials may also work as well, or better. Your best bet is to try it! I would lay a few test lengths, one using PVA, another using roofing felt adhesive (if it dosn't melt the material), and leave them outside. A crucial decision is how you will hold the curves in shape. For long straight track sections, I glued lengths of the foam, pre-cut to shape, to the concrete base, and glued the track to the foam, lining it up with a sraight-edge while the glue sets. For the curving sections I have a layer of rubbercrete under the foam so that I can use track pins. If you used pre-formed curves or used curve templates to keep the curve while the glue dries, the rubbercrete could be dispensed with. In all cases, I have finished with real stone ballast and diluted waterproof PVA. The sections done this way have lasted a year so far, the sections using synthetic ballast or ordinary PVA are now bare. If done properly, the finished ballast also helps keep the track in place.

One feature of a foam underlay is that it can reduce track noise as the train runs over it. However, the addition of a coating of stone ballast and dry PVA reverses this effect with a vengance, and the track noise becomes very obvious. This can of course be a good thing if the track sounds are realistic, and the stretches where I have cut notchs in the rail every 60' sound rather good.

The ballast is real granite bought from peco or other suppliers. I have found that real stone is the only material with any chance of staying in place when the glue is applied, and the only material to survive a winter. There are several schools of thought on the correct size for the ballast. This is partly because different sizes are correct for different types of track and different eras. Look at some photos from the location and era you are modelling. Peco supply "00" and "N" sized ballast. I have even used fine sand for sidings and mineral lines. The ballast is applied with a small spoon and adjusted with a paint-brush, keeping it level with or just below the tops of the sleepers, and providing a realistic shoulder over the edge of the foam.  Again, check some photographs of real track to see how it should look. Take care not to apply too much ballast, remembering that it is easier to add one more later than to take some away!

 



A Removable Crossover Module

One of the greatest difficulties I have found in running a 00 garden railway is keeping the track clean enough for good electrical continuity, and the worst problems are in the turnouts (points). I have therefore designed my latest group of turnouts, in the form of a crossover, as an easily-removable module which can be kept safely indoors when not in use.

The crossover temporarily in place, before it became a removable module.
The removable crossover has been tested in situ, and works well. It's currently electrofrog, wired for DC with the feed from the bottom right track and both frogs switched by the blade. However, all connections are brought to the edge of the PCB, so a change to external frog switching or DCC should be relatively easy, and is currently in progress.

I'll give it a bit more use before I waterproof the circuit board with several layers of suitable varnish, and apply the ballast. The single track from the tunnel comes in from bottom right, and reverts to double track. The spur at top right will be a freight-only branch to the top corner of the garden, and will require a severe gradient, probably about 1 in 15.

The removable bit is everything on the rubberised cork base with the veroboard inlays. The veroboard is connected to the rails by short wires soldered unobtrusively to rails, or the Peco-fitted wires where available. The red lines on the veroboard indicate the position of the used conductors on the underside.


The crossover during construction. (Image inverted compared with others on this page.)
 
The crossover in its initial working state, manually operated.

The assembly seems to be rigid enough for careful handling, though I normally keep it on an offcut of board when not in use. When fitted, it sits on a flat base which would normally be the base for the 3mm foam underlay. The rubberised cork is 3mm thick and the veroboard 1.6mm + solder joint. A larger assembly would become difficult to handle, but this one is fine.
It is currently connected to the tracks either side by sliding rail joiners. I use Gaugemaster, as they have a notch each side at one end, ideal for gripping with fingernails or fine-nosed pliers. This system has worked fine for a year for the viaduct. The intention long-term is to provide a connector or terminal block to the power and control bus wires.

Sunday, 9 September 2012

DCC Dabbling

The garden railway has now extended significantly in both directions, and from the only control point, which is roughly in the centre, it is not possible to see both ends. This makes operation difficult and detracts from the enjoyment of "watching the trains". I considered several solutions, and decided that the best solution would be one providing wireless controllers capable of operation along the full present and future route of the railway.

The "preferred solution" selected for trials was DCC, using the NCE Powercab controller with USB interface to a computer running JMRI Panel Pro software, and communicating wirelessly with a mobile device running WiThrottle software.

The first picture below shows the set-up in the summer-house. The Powercab and its power distribution panel are on the left, the laptop computer is running JMRI, and is hiding the small USB interface card. The three software packages (the USB driver, the JMRI control software and the WiThrottle application) were all downloaded free of charge via the internet.

For my existing DC control system, the summer-house is home for a mains transformer with a 16V AC outpot. This is taken by buried cable to a weatherproof box on a tree, containing a DIN socket compatible with Gaugemaster DC controllers, the 0-12V output going back down the tree to the track. For the DCC trial, the cable was unplugged from the transformer and connected to the DCC controller track output. A DIN plug was made up with two links to link the summerhouse cable to the track cable, and plugged in to the weatherproof box. Using this approach, the railway can switch between DC and DCC control with the minimum of effort.

The Power-cab controller and laptop running JMRI.
The WiThrottle user interface on an ipad.
 
 
The WiThrottle application can be run on the Apple iPod, iPhone or iPad, and probably other manufacturers' mobile devices. There is a free version which provides all the necessary functions; and a full version for £6.99 which provides some extra useful features. The picture above shows the two-loco controller from the full version, running on an iPad.

For communication between the mobile device and the main computer, a WiFi signal is necessary. As our railway is at the far end of a long garden, a WiFi extender was needed. This is a simple device which sits in a bedroom window overlooking the garden, receives the current home WiFi signals, and re-transmits them across the garden.

For the trial, two DCC-fitted locos were used, a Bachmann N class and a Bachmann sound-fitted class 37 diesel. The trials procedure was to "play trains", and see what happened!

A DCC-fitted N class. (The smoke was added later.)

A class 37 fitted with DCC and sound.

The trial continued into the night!
The main observations were:
  • It works!!!! "Playing trains" is now much more fun!
  • The WiFi signal suffers local nulls where control is temporarily lost. The effect of this can be minimised by remembering the weak-signal spots (usually behind trees or sheds), keeping the mobile device moving, and not leaving commands to the last monent.
  • Getting all the devices to talk to each other is trouble-free when switching on from cold. It's not so straightforward to regain control if it is lost in the course of the day. But it gets easier with experience!
  • Note that only certain functions of the fixed and mobile computers are used, so it may be possible to use "broken" equipment which would otherwise be destined for scrap.
  • The horn on the sound-fitted loco only works if the loco is moving slowly or not at all. Otherwise, it makes a long broken sound, during which the loco slows down dramatically. Sounds as if horn + engine sound + motor = more than controller's current capacity, but it shouldn't be. I need to investigate.


Monday, 30 July 2012

Cassettes

One of the tasks defined for phase 2 of the Garden railway was to " provide a method for easily loading and unloading trains from the railway. This should allow for trains of up to 12 coaches and two locos, though a train of this length may need to be split."

Some time ago, I purchased some 3/4" L-section aluminium and some 1/2" MDF. From these materials I fashioned two trial cassettes, one about 18" long and the other 4'. The current abrupt "end of the line" was given the necessary facilities to allow this cassette to be used.

The preliminary trial with the short cassett and a lashed-up support showed that alignment with the rails and successful transfer is possible.

Preliminary trials with a short cassette.

The initial trial with the 4' cassette and a "pre-production" support was also successful, showing that the cassette could be loaded on  the workbench with a train up to 4' long, carried without mishap to the railway, the cassette manually aligned and electrically connected, and the train driven away. An incoming train could be stopped on the cassette, which could be turned round and the train despatched back up the line. The cassette could also be left in place with no electrical connection, so that trains running on to it would stop automatically. This is particularly useful when young children (or forgetful adults) are driving.

A full cassette waiting to be uploaded onto the railway.

The cassette in place, ready to upload.

The cassete-to-railway interface, showing the electrical connection bulldog clips.

... and the train is driven onto the railway.



(more photos and text to come)

Saturday, 21 July 2012

The garden railway in context.

Here are a few pictures of the railway and the garden around it.

The lowest point of the current line is at the foot of the pond, beside the bean wigwam. Here, a train starts the ascent of the 1 in 50 bank, passing the Head Gardener at work behind the wigwam.


The train continues past the site of the garden seat, which has been temporarily removed by the civil engineers to improve access for track laying. A severe speed restriction is in force until this section is ballasted!


Just before the start of the single track section at the viaduct, our train passes a track-cleaning unit propelled by a class 59 diesel.

 
This is the view from above the quarry, looking over the tunnel to the construction site for the southeast extension. Behind the fence on the right, in a deep cutting, is the real railway.

Extension work beyond the tunnel.

... and this is the view from above the quarry, looking along the wall, with the line from the quarry curving in across the viaduct and down a series of reverse curves towards the bean wigwam and the lawn. Every curve on the railway has a reason; for example the curve of the viaduct and beyond is to clear the circular level area reserved for our hexagonal gazebo, used as the bar at the annual garden party!

The railway along the line of the wall.
 

Tuesday, 17 July 2012

To the End of the Line.

Here's today's progress on the Garden Railway.

The new section of track is almost complete; the cant (superelevation) on some of the curves needs increasing, and when we have a few consecutive days of good weather, the track needs ballasting. Most of the curves are of 7' radius, a few lengths are 5', and there is a short length of 4' radius. The picture below shows why the reverse curves are needed. To the right of the trackbed in the foreground is a path, to the right of which is a 5ft high earth "hump" between two trees, then the pond. The trackbed (and path) then has to get round the step in the fence, and be in the correct place at each end of the garden seat to allow the seat to stay parallel with the fence, before the track curves right again to avoid the vegetable bed and arrive at the lawn.

An elderly 3F has been taken off shunting duties to assist 34067 up the 1 in 50. The pacific can only manage 7 unassisted.
My interim scheme for "installing" trains on the railway is to use "cassettes". The design I have chosen is a strip of MDF with two strips of aluminium angle attached 16.5mm apart. The second picture shows a cassette on a trial lashup to keep it at the correct height. The "production" version should look a bit more professonal!

The cassette in the photograph uses "Tardis" technology to save space, and as you can see, although it is only about 18" long, it is in the process of unloading a 10-coach train with two locos.
;)

A trial lash-up to support a train cassette at the lawn end of the current line.

Saturday, 14 July 2012

More Progress

I've made some more progress in the gaps between the showers. Another 9' of track is laid, electrically connected, and test-run. All this section now needs is a few tweaks to the superelevation of the curves as a result of the testing, and ballasting.

A test train, ready to run over the newest section of track, not yet ballasted.

A test train runs down the new track (not yet ballasted) over the reverse curves.

In the first picture above, the continuing trackbed is just visible, protected from the rain by green plastic sheeting and wooden offcuts. To the left of the loco, and to the left of the first rain sheet, two concrete rectangles are visible on the ground. These are the bases for the back legs of a garden seat (temporarily removed during tracklaying), under which the track will run. This, along with the "kink" in our garden boundary at this point, is the reason for the fairly complex series of reverse curves in the area.

I now only have another 9' of track to lay to reach the lawn, which marks the end of permanent trackwork at this end of the line. From here, there will ultimately be a removable section across the lawn, then the permanent trackbed will continue up the other side of the garden to complete a circuit.

BREAKING NEWS 15/7/12: A dry, sunny day provided the opportunity to lay the final 9' of track to the lawn, adjust the cant (superelevation), and run a test loco over it. I still have to solder the electrical connections on this section, and ballast all of the latest 18' of track. I can then either do the reballasting necessary on Quarry Bank, or continue work on the extension at the other end of the line. Or both. I just need some dry weather.

While I was working between rain-showers on the new track, the previously completed trackwork was good and wet, and made an ideal thoroughfare for the numerous gastropods with which we share the garden. If any gastropod is reading this, please be advised that trespassing on the railway is dangerous and can result in death or serious injury. As soon as I find someone who speaks Sluggish, I will get some warning signs put up.


A trespasser on the main line.

Snail-Rail?

If you wonder what I do while it's raining and I can't lay tracks, one option is to watch the real trains at the end of the garden. I must admit that it's an option I don't often take up, but last Monday was the 45th anniversary of the last steam-hauled public-service train on the Waterloo to Weymouth line, and an excursion train was run over the route "in memoriam".

35028 "Clan Line" on a Cathedrals Express excursion to Weymouth, 9.7.12.

35030 "Elder Dempster Lines" leaves Dorchester with the last steam train to Waterloo, 9.7.67

If anyone from Network Rail is reading this, please note from the above picture that the undergrowth on your land is getting out of hand again, and is starting to intrude on my photographs!



And finally ....


The fireman of a 3F mops his brow after a gruelling ascent of the Mendip hills.



Saturday, 30 June 2012

Back to Work

After an enforced break in all but the lightest of my modelling activities, I now have permission to step up a grade in the constructon work. So for the past two days I have been extending the garden railway trackbed past the pond.

The trackbed under construction. The pond is to the right in the middle distance.

The concrete embankment was laid some months ago, and the plasticine shuttering was in place for the closest metre in the picture. This was repaired where it had been chewed by a fox, and extended past the site of the seat (temporarily removed to improve access), to the furthest point visible in the picture, which is at the edge of the lawn. The rubbercrete trackbed was extended by about 2 metres, as shown in the picture, but then I ran out of materials. Before I can go any further I will need to procure some more cement and SBR for the rubbercrete.

I am particularly pleased with the effect of the reverse curves; it should look superb with the double track in place and a double-headed 12-coach train snaking round the curves. Although the curves appear sharp, in fact the sharpest is a radius of 5ft.

When the track is laid on this section, it will be as far as I intend to go at this end of the line, until the next phase of work. A removeable support will be provided to allow cassettes (strips of board fitted with a length of track) to be physically aligned and electrically connected. These will allow trains to be "loaded" onto and "unloaded" from the railway.

In another month or two, when I am able to lift heavy loads again, work can restart on extending the other end of the line, at the foot of the garden by the railway fence!

A pack of modelling clay, as used for shuttering the rubbercrete.

Wednesday, 25 April 2012

Couplings

You can call me a masochist, and you might be right. Because I am one of those strange people who choose to use three-link couplings on their railway models.

I made this decision many, many years ago on the basis that most of the proprietary auto-couplers make a lovingly-constructed and decorated model look more like a toy. And in my early modelling days, construction was mainly from kits, for display and photography, so auto-couplers provided little benefit.

The difficulty was finding a three-link coupling which looked correct and worked reliably. I have a box filled with examples from every conceivable manufacturer, many of who have long since gone out of business. All have one thing in common; they fail to meet one or both of these requirements.

Over the years, experience has softened my resolve a little. Freight stock must have realistic couplings. Passenger coaches with gangway connections are less critical. Firstly, they are usually connected semi-permanently into sets. Secondly, the gangway connection largely hides the coupling. Thirdly, the same gangway connections make coupling up a three-link coupling all but impossible. So an alternative is needed, with an added requirement for realistically close coupling.

So, where do I find suitable couplings. Well, the only three-link couplings to have come close to meeting my requirements are those supplied by Exactoscale. They look right, are made to tight tolerances which so far have been consistent, are not too difficult to assemble, and work reliably if care is taken in fitting to keep a constant and pre-refined dimension between buffer face and hook. You need to work out this dimension for yourself, based on the smallest radius track curve you want to cater for, the length and wheel-spacing of the vehicle, and whether or not the coupling hook and/or buffers are sprung. It needs to allow the coupled vehicles to get round your worst curves without the buffer binding, but not be further apart than necessary at other times.

Exactoscale provide instanter links as well as standard links, and the first picture shows one of these fitted to a Bachmann 9' wheelbase wagon.


A Bachmann wagon with instanter-link coupling chain and hook by Exactoscale.

Given that most proprietary models are now to at least as high a standard as most kits, and not very different in price, wouldn't it be nice if they were already fitted with a scale coupling hook? Well, Bachmann have achieved this on some of their recent models. The next picture shows Exactoscale coupling chain on the original hook of a Bachmann 16T mineral wagon. All that was required was to ease the two chain apertures slightly to ensure free movement, and it works perfectly. Don't get too excited though, as most Bachmann hooks are too thick or the wrong shape.

A Bachmann wagon with Exactoscale chain on original Bachmann hook.

As you've probably noticed, I have so far avoided the thorny subject of screw couplings. I solve the problem on freight stock by using instanter links on "XP" rated vehicles. On locos, I use Hornby screw couplings. They are the best-looking I have found, and the hook works well with the Exactocale links from other vehicles. However, I regard the Hornby chain as cosmetic only (and they are sold as such), so I only fit them to locos. If I want to couple two locos together, I use a set of loose links.

A Bachmann loco with Hornby dummy screw-link coupling.

Finally coaches. I don't have one single solution for coaches. To date I have used the supplied tension-lock coupling, but they require between 1 and 2mm of slack to operate, so can never by their design  provide really close coupling. The best solution so far has been the alternative couplings supplied with some Hornby coaches. These fit into a clever mechanism under the coach which increases the gap when the vehicle goes round a curve, so on the straight they can actually have buffers and/or corridor gangway connections touching between coaches. Unfortunately, the manufacturers don't seem yet to have confidence in this mechanism, and still provide couplings which are longer than necessary. This can be circumvented on Bachmann Mk1 coaches by using the Hornby couplings (see next picture), which are just the right length when coupled and have minimal slack. In fact thay are too close to couple by pushing the coaches together, and you need to gently push the coupling under the coach with a screw-driver or similar, until it clicks.

Compatible couplings are made by Roco, and are slightly shorter. They are ideal for the Hornby Maunsell coaches, with the same caveats as above. I haven't experimented with any other coach classes. You will also find that coupling a Maunsell to a Mk1 may be unreliable, as the NEM pocket on the Bachmann Mk1 is not at the NEM specified height, and the supplied tension-lock couplings have a joggled arm to correct this.

A Bachmann Mk1 coach with Hornby Roco-type coupling.

How do I go about coupling and uncoupling our vehicles? The coaches, whenever practical can be kept together in sets. It helps if they can be stored on "cassettes". The three-link couplings I always make with a magnetic bottom link (Exactoscale supply these). This allows a magnetic pole to be used, available commercially from a number of sources, or made with a tiny magnet, a brass pole, and a miniature LED torch, all held together with epoxy adhesive.

I haven't mentioned cost yet. None of the solutions offered here is cheap. However, I have spent so much time and effort in the past on items that ended up being of little use, that I now just pay the money at the expense of some other item in the modelling budget, and don't worry too much about it.

This review still leaves some questions unanswered; for example, how to connect the loco and coaches. I am still looking for a consistent solution here, and in the meantime I assess each case separately, usually using a vehicle with a different coupling at each end as an interface. If you have any better ideas, let me know!


Supplies:


Three link coupling parts: Exactoscale Ltd 4CP D01A, 4CP 303A, 4CP 312A, 4CP 311A, available from www.wizardmodels.co.uk

Cosmetic screw coupling: Hornby X5069 available from www.hornbyspares.com

Coach coupling: Hornby X8220 available from http://www.hornby.com/shop/rolling-stock/rolling-stock-accessories/r8220-nem-hornby-couplings/ or Roco 40270 available from www.gaugemaster.com

Magnetic coupling pole: available from www.lanarkshiremodels.com


Micro magnets: available from www.magnetexpert.co.uk.


Tuesday, 24 April 2012

April Showers

The garden railway hasn't had much use lately. After a warm, dry March we are now almost at the end of a very wet April, not ideal for garden running. I did find one gap in the rain to test-run an N class 2-6-0, which looked fine climbing the 1 in 50 to the tunnel.

A fresh out-of-the box Bachmann N class 2-6-0.