martin_wynne

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Kingussie:

Many thanks Gordon. I have updated the S4 discussion with a copy of your pic. The wiper contacts do now seem to be much better aligned to the tracks. I'm still not happy with the use of copper track for switching traction feeds. Suppose for example that a metal wheel has been left standing bridging a rail gap. Changing the points will then cause these switches to make into a dead short. If that exceeds 5 amps the DCC power foldback will probably be fast enough to prevent significant damage to the copper track. But suppose the short-circuit is only sufficient to draw 4 amps? These contacts will be damaged (Circuitron rate them for switching 1 amp max), and once damaged are unlikely ever to show zero ohms again, causing poor running over the crossings. I still regard a relay as the best solution for long-term reliability and performance. The wiper switches are fine for interlockings, signals and indicators, etc., where an over-current situation is unlikely. regards, Martin.

Hi Duncan, Very little FB track was laid before the 1950s, and most of that was experimental in nature. Having said that, the SR company did lead on track developments in the post-grouping period. Even if there was some trial FB in the Winchester area in the 1940s you can be sure that it was confined to main running lines. All branch and secondary lines, goods loops, yards and sidings would have been bullhead -- as some of them still are. Martin.

Hi Gordon, Do you mean the internal polarity switches on Tortoise motors? You may want to look at: http://www.scalefour.org/forum/viewtopic.php?p=1919#p1919 http://www.scalefour.org/forum/viewtopic.php?p=1855#p1855 http://www.scalefour.org/forum/viewtopic.php?p=1868#p1868 Whenever I have mentioned the unsatisfactory design of these internal switches it is always pooh-poohed by those who say they have used dozens of them for years and never had any problems. Nevertheless having examined the internals of several of these motors I would not myself use the internal switches for crossing polarity switching. Apart from the poor dimensional design, the basic principle of using thin copper-clad track as a switch is flawed. There is a risk that under fault conditions these contacts will be switching into a dead-short, causing the thin copper track to be burnt. After which it will display a poor high-resistance connection for the rest of its life. Especially when there is a simple and far more reliable solution -- simply slave a relay across the motor connections to provide the polarity switching. All it needs is a relay in series with a diode connected to the Tortoise motor terminals. Small sealed SPDT relays are readily available and not too expensive, and are a fit-and-forget component needing no adjustment or maintenance. Just dab them in a convenient spot under the baseboard with the glue gun: economy (for non-DCC - 5A contacts): http://uk.rs-online.com/web/p/non-latching-relays/0492907/ industrial (for DCC - 10A contacts): http://uk.rs-online.com/web/p/non-latching-relays/0351601/ Use DPDT versions if you need additional switches (e.g. for diamond-crossings). regards, Martin.

• You don't need code 75 flat-bottom rail. The correct size for the flat-bottom rail in your photo is code 82. The code 75 flat-bottom rail which Peco use is sized for H0 and is actually underscale for 00. The prototype BS-110A rail in your picture is 6.1/4" high, which scales to code 82. regards, Martin.

Hi Steve, Al, The check rail gauge is the most important gauge in the set. You could just about get away with setting the other rails by eye from the template, but not the check rails. They must be the correct distance from the opposite rail (not the rail next to them) in order for wheels to run properly through the crossings (frogs). They are set using the check rail gauges. It's preferable to have separate check rail gauges for two reasons: 1. It allows you to have some gauge-widening on sharp curves. When you widen the gauge, the check rail gap must widen by the same amount. It can't do that if it is set using a multi-slot combined gauge. 2. If there is a problem with the track, you need to be able to check it using the gauges. This is next to impossible to do with a multi-slot gauge. If it won't fit on the rails it is very difficult to say which of the rails is wrong. I've already posted this below half a dozen times in various topics on RMweb, and on other forums, but I may as well post it yet again: A is the check gauge. It is the most critical dimension in pointwork. If this dimension is too small, wheels running from left to right can hit the nose of the vee and very likely derail, or at least bump. If this dimension is too large, the wheel backs will bind or jam on the check rail. To make sure it's correct, the check rail is set using check gauge tools. For 00-SF and 00-BF this dimension should be 15.2mm. You can use the same check gauge tools for both these standards (they are both running the same wheels). B is the crossing flangeway gap. It's also important. If this dimension is too small, the wheel backs will bind or jam on the wing rail. If this dimension is too large, the gap in front of the nose of the vee will be too wide, and the wheels may drop into it with a bump. This gap is set using a small piece of metal shim called a crossing flangeway gauge shim. For 00-SF it should be 1.0mm thick. For 00-BF it should be 1.3mm thick. C is the track gauge. It shouldn't be less than the specified dimension, but it can be wider. It is often widened on sharply curved track to ease the running of long-wheelbase vehicles. The track gauge is normally set using roller gauge tools, or alternatively using a 3-point gauge tool, which automatically widens the track gauge on sharp curves. For 00-SF this dimension shouldn't be less than 16.2mm. For 00-BF it is normally 16.5mm. D is the check rail gap. The width of this gap doesn't matter a damn, providing it is wider than the wheel flanges. It's whatever you end up with after setting A and C correctly. But where the check rail is combined with a wing rail in complex formations (i.e. in parallel-wing V-crossings) it must be the same as B. p.s. Al -- Bullhead rail will fit in the chairs only one way up. That is with the thick edge on top, and the thin edge at the bottom in the chairs. This is not always intuitive for beginners. The prototype reason is so that there is extra metal on the running head to allow for wear. regards, Martin.

Hi Al, • No -- use the track gauges on the left if you don't want to make any changes to RTR wheels. It really is unfortunate that after all these years C&L still don't make it clear on their web site that their "ordinary" 00 gauges on the right are for the DOGA-Fine standard only, which requires all wheels to be widened to 14.7mm or 14.8mm Back-to-Back, and that their 00 Back-toBack gauge is also for this. This must have caused countless problems and disappointment to modellers over the years, as these gauges are also supplied in the 00 turnout kits. Especially when they now also supply the 00-SF gauges on the left -- which don't require any modifications to most RTR wheels. They ought really also to supply standard 00-BF 16.5mm gauges too -- although the 00-SF check gauge tool is applicable for both. The blame for this state of affairs lies with the former owner of the C&L business who decided to foist the specialist DOGA-Fine standard on everyone whether they wanted it or not, or understood what they were getting. But it is surely time that the present C&L business properly explained what they are selling. regards, Martin.

Two come to mind -- Charford by John Charman, and the Berrow Branch by Mac Pyrke.

Hi Al, Start with the first half-diamond and then click the tools > make diamond-crossing menu item. Templot will create the other one. I have recently made a new video about creating a single slip. You should be able to watch it directly from Templot, click here: If not, you can watch it on the Templot web site, here: http://templot.com/companion/index.html?add_slip_roads.htm regards, Martin.

Clue needed? Passengers here may be taking cake on a boat trip.

The answer lies in the socks. Thick socks -- I'm warm all over. Thin socks -- I'm cold all over. How do my hands know what I'm wearing on my feet?

The purpose of this fence is clearly to prevent anyone falling in the wrong part of the canal. Or? Martin.

Pointwork can be placed in the middle of a straight gradient, but not in the vertical curve at each end of a gradient. Even if there are no derailments, the switch blades are liable to bind and not move over cleanly. The same applies in the middle of a curved gradient, although a gentle curve on a not too severe gradient is usually ok. regards, Martin.

Hi John, Yes, 50mm centres is the 00-BF standard, similar to Peco and good down to 24" radius or maybe a bit smaller. For the crossover size everything depends on your acceptable minimum radius in the outer turnout? Toy trains traditionally go down to 15" radius but unless you will be running only old toy trains I don't think you can sensibly go that sharp. Perhaps a suitable absolute minimum would be 450mm / 18" radius? To get the easiest possible radius in the shortest turnout you need to select the non-prototype model switches in the list, and a generic type V-crossing. Using the shortest 1:24 model switch and generic 1:6 V-crossing you can get this crossover: 750mm radius in the outer double-track and 700mm in the inner double track. Generic V-crossings. The turnout radius in the outer turnout is just over the 18" limit at 464mm / 18.3". These are both Right-Hand turnouts. This seems to be about as tight as you can sensibly go with kit-built models, and even then is likely to mean carving lumps out of them for loco bogies to swing, carving behind splashers for extra side-play on wheels, wires across the buffers to prevent locking, etc. Against that the big advantage of putting the crossover on a curve is that there is no reverse curve to cause problems. regards, Martin.

That's true Keith, but I was asked to explain the principle. You can't have true concentric curves through the running lines of a curved crossover unless both turnouts are of the same hand. Which means the inner turnout will have contraflexure. And no such turnouts are available from Peco (or any other manufacturer as far as I know). Whereas for handbuilding a single click in Templot produces exactly what is wanted. But that's only any use if users know it's what they want. John said he was planning to use handbuilt track for his Minories plan. regards, Martin.

As a p.s. to my previous post, often the curving radius in the main roads is more gentle. In which case contraflexure produces a Y-turnout effect, rather than an apparent change of hand. Here is such a crossover. Both of these turnouts are left-hand, just as they would be if the main lines were straight, and would still be if the main lines were more sharply curved: linked from: http://bristol-rail.co.uk/wiki/File:Filton_Abbey_Wood92.jpg Martin.

Hi Ian, The hand of a turnout is determined by the hand of the switch. The direction of curving through the turnout is irrelevant. It is an important distinction because it controls the speed limits through the turnout. The hand of a switch means the direction of the switch deflection angle. This is a left-hand switch: Traffic traversing the main road straight ahead sees no deflection and can proceed at full line speed. Traffic traversing the diverging turnout road to the left is suddenly deflected from its path at the switch deflection angle. In a B-switch that angle is 1:32. In a C-switch it is 1:40. You can see the switch deflection angle as a sharp bend in the left-hand stock rail, called the "set". The planing of the switch blades matches the same angle. Because of the switch deflection, there is always a speed limit for traffic traversing the diverging road of a turnout, sometimes a severe limit. Crossovers between running lines are always arranged so that the switch deflection is towards the crossover road, so that there is no speed restriction for traffic on the running lines. This means that both turnouts in such a crossover are always of the same hand. Here below you can see that for the straight track, both turnouts are obviously left-hand. When the whole formation is laid into a curved track, the turnouts don't change. They are both still left hand: When the curving through a turnout goes in the opposite direction from the hand, as in the top-right turnout, it is called "contraflexure". In Templot the curving radius in the main road is shown as a negative value for contraflexure. If the turnout at top-right was changed to a right-hand turnout, traffic on the running line would see the switch deflection angle and be subject to a speed limit. regards, Martin.

Bricks and ducks:

A proper double-track crossover always has both turnouts of the same hand, even when in curved track. This is impossible to create using Peco curved turnouts (or any other ready-made track that I know of). The Peco exit angle of 12 degrees (1:4.7) is far too sharp for passenger trains, the normal limit being 1:8 for straight crossovers and then only dead slow. Curved crossovers can be created without a reverse curve, but still need a long crossing angle to keep the radius sensible. A good size for model curved crossovers is C-10. Here's a print from Templot showing that: edit: the inner turnout (but not the outer) could be changed to a B-10, saving a bit on the overall length. regards, Martin.

Hi Gordon, Well it's getting on for 30 years since I last built a platform -- these platforms on Adavoyle Junction in fact: The entire platform was first constructed from balsa wood. I'm fairly sure we used 3mm or more likely it would have been 1/8" thick in those days. But not the overhang -- the sub-surface was trimmed flush with the side walls. It was cut lengthwise, from 4" and 3" wide balsa planks. I remember cutting the framework strips from balsa on the circular saw, to provide the correct height, but I can't now remember the actual dimension -- the intention was for the balsa sub-surface to be 2mm below the finished platform top. Then the coping stones along the edge were laid using Evergreen 2mm x 6mm plastic strips, scribed to represent the individual stones and overhanging the side walls a bit. There is not much overhang on Irish platforms, see: That left a space between the coping strips 2mm deep which was first filled with 1/16" cork sheet, and finally surfaced with 10 thou plasticard to represent the slabs. The latter being scribed and pre-painted streaky grey, and then cut into strips laid individually cross-wise in order to create the staggered joints. I remember a good few evenings spent making and laying those strips. I found a couple of pics showing the layout under construction in 1986. Showing the balsa sub-base and the coping strips added: I'm not sure if all this helps you much -- it is all such a long time ago now. But I do remember the ease of fixing items onto the platform by simply pushing in thin pins. More Adavoyle Junction pics: http://templot.com/GNRI/adavoyle.htm regards, Martin. edit: link added.

Don't overlook balsa wood as a platform sub-surface. Items can be attached quite firmly with Peco track pins through their feet (people) or glued into the corners of buildings, or into the base of lamp posts, etc. The items can then be easily removed and replaced or moved at any time without needing drilling or glue. Martin.

Man and bike in Runcorn grot: https://www.flickr.com/photos/21602076@N05/4295697573/in/photostream/

If you are looking for something a bit different but not too difficult to build, how about a "Barry Slip"? Two turnouts of the same hand, reversed and overlapped. They are called Barry slips because they were a feature of the sorting sidings at Barry Docks in South Wales: Thanks to Sandy Croall for the pic. This one is at Beverley: Thanks to Mick Nicholson for the pic. Martin.

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