A Turntable For Model Railroads

Way back when, before diesel-electric locomotives were a thing, trains weren’t really able to go backwards too well. Also it’s sometimes necessary to turn carriages around in a small space. For that, the railway turntable was invented. If you want to implement one on a model layout, this project from DIY & Digital Railworld is for you.

The project is at an early stage – thus far, laying out how to set up an Arduino Uno using a potentiometer to control the speed of a stepper motor, which rotates the turntable. The turntable itself is a 3D printed part sourced from Thingiverse, designed to suit the specific stepper motor used.

This has the easy part sorted – rotating a piece of track through 360 degrees to orient a train properly. However, there’s significant work ahead. Power needs to be hooked up to the rails, and a system for accurately aligning the turntable with outgoing tracks needs to be devised. This is particularly relevant for N-gauge setups, where tolerances are everything.

We’d love to know how you’d tackle the various issues to build a working model turntable in the comments. We’ve seen some serious model railroad builds before around these parts. Video after the break.

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The Arduino Hits The Rails

Certain hobbies come in clusters. It isn’t uncommon to see, for example, ham radio operators that are private pilots. Programmers who are musicians. Electronics people who build model trains. This last seems like a great fit since you can do lots of interesting things with simple electronics and small-scale trains. [Jimmy] at the aptly-named DIY and Digital Railroad channel has several videos on integrating railroad setups with Arduino. These range from building a DCC system for about $45 (see below) to a crossing signal.

There are actually quite a few basic Arduino videos on the channel, although most of them are aimed at beginners. However, the DCC — Digital Command and Control — might be new to you if you are a train neophyte. DCC is a standard defined by the National Model Railroad Association.

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Retrotechtacular: Operation Smash Hit

Judging by the number of compilations that have been put online, one of the not-so-secret vices of the YouTube generation must be the watching of crash videos. Whether it is British drivers chancing their luck on level crossings, Russians losing it at speed on packed snow, or Americans driving tall trucks under low bridges, these films exert a compelling fascination upon the viewing public intent on deriving entertainment from the misfortunes of others. The footage is often peripheral or grainy, having inevitably been captured by a dashcam or a security camera rather than centre-stage on a broadcast quality system with professional operation. You can’t predict when such things will happen.

There was one moment, back in 1984, when predicting a major crash was exactly what you could do. It was a national event, all over the TV screens, and one which was watched by millions. The operators of British nuclear power stations wished to stage a public demonstration of how robust their transport flasks for spent nuclear fuel rods were, so after all the lab tests they could throw at one they placed it on a railway test track and crashed a 100mph express train into it.

Water escaping during drop test.

This was as much a PR stunt as it was a scientific endeavour, and they lost no time in promoting it across all media. The film below the break was part of this effort, and takes us through the manufacture of the flask forged in one piece from huge billets of steel, before showing us the tests to which it was subjected. The toughest of these, a drop-test onto a corner of a fully laden flask, resulted in a small escape of the water contained within it. It was thus decided to conduct the ultimate test to ensure full public confidence in nuclear transport.

The Old Dalby test track is a section of a closed-to-passengers line in the English Midlands that was retained by British Railways as a proving ground for new locomotives. In the ultimate test of rail transport for nuclear waste, a flask was placed on its side across a piece of the track, and a train formed of a withdrawn 1960s locomotive and a short rake of 1950s carriages was accelerated without a driver over several miles to 100mph.

An instant before impact, we see the underside of the derailed car. The flask is between it and the locomotive.

[Nigel Harris] for Rail magazine wrote an almost funerial description of the destruction of locomotive 46009 25 years later in 2009, and as he reported the flask survived with only superficial damage and a tiny loss in pressure. The event was hailed as a success by the nuclear industry, before fading from the public consciousness as nuclear power station operators prefer to remain out of the news.

It is questionable how much the Old Dalby crash was for the cameras and the public, and how much it was for the scientists and engineers. But such destructive tests do serve as a means to gain vital test data that could not be harvested any other way, and have been performed more than once in the aviation industry. Later in the same year a Boeing 720 was crashed for science in the USA, while more recently in 2012 a Boeing 727 was crashed in Mexico.

Crashing an express train into a nuclear flask is something not likely to be seen again, it was a one-off event. But one thing’s for sure, our inability to turn away from watching a train wreck is nothing new. YouTube and ubiquitous cameras certainly make crashes available with a few keystrokes. But from the 1984 cask crash test, to the the spectacle of Crush, Texas back in 1896, the sheer power shown in these crashes seems to have a siren song effect on us.

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This Coin Cell Can Move That Train!

[Mike Rigsby] has moved a train with a coin cell. A CR2477 cell to be exact, which is to say one of the slightly more chunky examples, and the train in question isn’t the full size variety but a model railroad surrounding a Christmas tree, but nevertheless, the train moved.

A coin cell on its own will not move a model locomotive designed to run on twelve volts. So [Mark] used a boost converter to turn three volts into twelve. The coin cell has a high internal resistance, though, so first the coin cell was discharged into a couple of supercapacitors which would feed the boost converter. As his supercaps were charging, he meticulously logged the voltage over time, and found that the first one took 18 hours to charge while the second required 51 hours.

This is important and useful data for entrants to our Coin Cell Challenge, several of whom are also going for a supercap approach to provide a one-off power boost. We suspect though that he might have drawn a little more from the cell, had he selected a dedicated supercap charger circuit.

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Retrotechtacular: How To Repair A Steam Locomotive

Steam locomotives, as a technological product of the 19th century, are not what you would imagine as fragile machines. The engineering involved is not inconsequential, there is little about them that is in any way flimsy. They need to be made in this way, because the huge energy transfer required to move a typical train would destroy lesser construction. It would however be foolish to imagine a locomotive as indestructible, placing that kind of constant strain on even the heaviest of engineering is likely to cause wear, or component failure.

A typical railway company in the steam age would therefore maintain a repair facility in which locomotives would be overhauled on a regular basis, and we are lucky enough to have a 1930s film of one for you today courtesy of the British London Midland and Scottish railway. In it we follow one locomotive from first inspection through complete dismantling, lifting of the frame from the wheels, detaching of the boiler, inspection of parts, replacement, and repair, to final reassembly.

We see steps in detail such as the set-up of a steam engine’s valve gear, and it is impressed upon us how much the factory runs on a tight time schedule. Each activity fits within its own time window, and like a modern car factory all the parts are brought to the locomotive at their allotted times. When the completed locomotive is ready to leave the factory it is taken to the paint shop to emerge almost as a new machine, ready for what seems like a short service life for a locomotive, a mere 130 thousand miles.

The video, which we’ve placed below the break, is a fascinating glimpse into the world of a steam locomotive servicing facility. Most Hackaday readers will never strip down a locomotive, but that does not stop many of them from having some interest in the process. Indeed, keen viewers may wish to compare this film with “A Study in Steel“, another film from the LMS railway showing the construction of a locomotive.

LMS Jubilee class number 5605, “Cyprus”, the featured locomotive in this film, was built in 1935, and eventually scrapped in 1964 as part of the phasing out of steam traction on British railways.

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Tiniest Control Board Fits Inside an N-Gauge Model Train

[kodera2t] discovered the VL53L0X Time of Flight sensor and thought it would make a great way to control the operation of a model train without touching it. He explains it in his own words in the demo video.

The sensor was small enough for an N-gauge train, which translates to 1:148 scale or about 9mm from rail to rail. His idea was to build a tiny control board that could fit inside the locomotive: 10mm by 40mm. His board consists of the ToF sensor, an ATMega328P-MMH, USB-serial, and a Texas Instruments DRV8830 motor driver. he powers the board via the 6V running through the track.

Right now [kodera2t]’s using the ToF as sort of a gestural controller to get the train to start rolling, but one could imagine the sensor could be incorporated into more advanced programming, like having the train speed up on straightaways and slow down on a curve, based on the height of the bridge over it.

We’ve published a bunch of [kodera2t]’s tiny circuit board projects here on Hackaday, including the smallest basic computer, his minimal frequency counter, and his VFD amplifier.

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And the Grandfather of the Year Award Goes to…

Hacker dads often have great plans for all the fun projects they’ll build for their kids. Reality often intrudes, though, creating opportunities for hacker grandfathers who might have more time and resources to tackle the truly epic kid hacks. Take, for instance, [rwreagan] and the quarter-scale model railroad he built for his granddaughter.

Taking inspiration from a 1965 issue of Popular Mechanics, grandpa hit this one out of the park. Attention to detail and craftsmanship are evident from the cowcatcher to the rear coupler of this 4-2-0 steam engine replica, and everywhere along the 275 feet of wooden track — that’s almost a quarter-mile at scale. The locomotive runs on composite wood and metal flanged wheels powered by pair of 350-watt motors and some 12-volt batteries; alas, no steam. The loco winds around [rwreagan]’s yard through a right-of-way cut into the woods and into a custom-built engine house that’ll make a great playhouse. And there are even Arduino-controlled crossbucks at the grade crossing he uses for his tractor on lawn mowing days.

The only question here is: will his granddaughter have as much fun using it as he had building it? We’ll guess yes because it looks like a blast all around. Other awesome dad builds we’ve covered include this backyard roller coaster and a rocketship treehouse.

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