Twinwoods & Bedford

Twinwoods & Bedford - 02 - Table Design

The track layout has round shapes. We like the tables to follow these rounds. This means a lot of saw work, with good accuracy.

The plan is to first draw the table lines on the wooden plates such that it’s easy to follow them with a jigsaw. We’ll first make a drawing with the correct dimensions in Fusion 360. Using a 10 cm grid we can transfer the table coordinates at the grid intersections to the wooden plates, on which we first also place the grid dots. Then we play ‘connect the dots' and we'll have the real size drawing on the wood.

The plus of using Fusion 360 is that once we have a drawing we can simply turn it into 3D shapes and get a good feel for how it’s going to look.

Another option could be to print the layout in real size via SCARM. But then to accurately place all A4 sheets on the wood and transfer them to saw lines is still a challenge.

We’re curious what other methods have been used to transfer the layout to the table and create accurate saw lines?

This is a link to video Twinwoods & Bedford - 02 - Table Design

It's interesting to see a design that's operationally all about train movements. (I guess the models used will represent passenger services operated by multiple unit type trains?) Operation is my primary interest, though in a locomotive hauled scenario; and the scenery is minimal, it's all about timetable operation of the trains.

Ruud Boer said:

• We like to have a lot of rails
• It doesn’t have to resemble real world
• We like to be able to drive around on a loop
• We also like to drive dead end to dead end

Click to expand...

You have all that in the plan. And it is very suggestive of a well known UK railway operation if that matters to you at all! What is amusing from my perspective is that the East midlands station names make a 'false connection', yet there is a location in the UK where such a very dense MU operated network exists. If names like Addiscombe, Brixton, Croydon, Dartford, Epsom, were used, that immediately suggests the appropriate location. South of the river Thames on the densest MU operated network anywhere in the UK. Whatever, your choices are your own to enjoy.

Have fun building it, I have not a clue of how to map that onto the plywood for accurate cutting, being an L girder afficianado, with free hand cutting of the track bed...

Twinwoods & Bedford - 03 - Widen the Aisle

We had performed tests to investigate if we’d be able to pass through a narrow space of 30 cm. The tests were performed with two desks spaced 30 cm apart. The tests were positive, as in ‘it’s doable’, but deks are only 74 cm haigh, which means you pass them below your bum, with your legs. Yesterday we were able to perform similar tests with tables at the intended height of 110 cm … that’s a whole other matter. Now you pass the tables above your bum, with your belly. How come that does not fit nicely anymore? I have no idea.

Conclusion of the test was that we need to modify the layout. To create more aisle space we had to give up our criterion of a minimum curve diameter of 120 cm, we made the inner curve around Bletchley station 100 cm and we also created a small bend just after the turnouts into Bletchley. This had the desired result … we now have a 50 cm aisle width.

In the process the idea popped up to extend Bletchley station over the curve, creating a tunnel. This helps make the layout somewhat more interesting. It’s not decided yet … let’s say this has an 80% probability.

This is a link to video Twinwoods & Bedford - 03 - Widen the Aisle

Twinwoods & Bedford - 04 - Simulation with EEP

Before putting the saw into the wood, constructing tables and laying track we planned to do two simulations, one in Traincontroller and one in the very nice EEP 3D (model)railway simulator, which this video is about.

Any possible issues found in this stage will be much easier to resolve than after the tables are mounted and track has been laid. Besides … it’s just fun to create a layout in EEP and have trains run fully automatic, thanks to the additional software that was created in a joint cooperation with German hobby friend Frank Buchholz.

So … what are we looking for? Well, mainly if the layout looks nice … in our eyes that is, some will think there’s too much track and too little scenery, but that’s how we like it . We also want to check if train flow is smooth, varied, and without any traffic jams or hiccups, or opposite to see if there are any tracks that are never/seldom used.

This is the link to video Twinwoods & Bedford - 04 - Simulation with EEP

For those who like to try out EEP:

This is a link to EEP on Steam.
This is a link to the free EEP Automatic Train Control software.
This is a series of videos on EEP automation

Twinwoods & Bedford - 05 - TrainController


The second test before sawing the tables is to try the layout in TrainController. TC is a Windows program for control and automation of digital model railways. It has a simulator mode which makes it possible to already test a layout before it is physically there.

TC uses block control. Every block has an entry sensor. These can be reed switches operated via a magnet under the train, or current measurement, or other. The sensors tell TC when a train runs into a block. If it has to stop in this block, the brake marker is the point where the train starts to slow down, until it reaches the stop marker. Distances between the sensor and the brake- and stop marker are user specified.

Once the layout has been divided into blocks, ‘Schedules’ can be defined. These specify which trains should drive where. Once the train reaches the end point of the Schedule, TC selects a new Schedule from a list of ‘successors’. This way fully automatic traffic is created, while it still is possible to drive trains manually, in between the automatic traffic.

The test is performed to see if traffic keeps flowing, if there are no hiccups, or deadlocks, or if there are blocks where no train ever comes. All went well … so … it’s time to start sawing the tables!

This is the link to video Twinwoods & Bedford - 05 - TrainController

Twinwoods & Bedford - 06 - Sawing the Table

The two simulations (EEP video 4, TrainController video 5) showed us that this layout can have an interesting train traffic flow. This gave us the confidence to now start sawing the wooden plates for the table.

The challenge was to transfer the drawing from the PC to the boards to have the lines to saw along. We did this by first placing a grid of boards over the layout drawing. This enabled us to read out the x,y coordinates of strategic points per board. Two points are needed for a straight line, three for a curve. We used a bendable plastic strip to draw smooth curved lines on the board.

This is the link to video Twinwoods & Bedford - 06 - Sawing the Tbale

Twinwoods & Bedford - 07 - Mounting the Table

After having sawn the 9mm wooden plates in their respective shapes the tables can be mounted.

Along the wall the plates rest on a full length beam. The peninsula and the aisle side of the tables rest on legs, connected via beams to create a support frame. All legs have height adjustable feet.

In the meantime the lower and upper tables and the peninsula are mostly done. What’s left are the two ramps. These will be sawn out of 3mm board because they need to be flexible. The ramps are curved and need to be twisted some to mount them flat to the surface at both sides.

This is the link to video Twinwoods & Bedford - 07 - Mounting the Table

Twinwoods & Bedford - 08 - The Table is Ready!

This week a hardware milestone has been reached: the woodwork for the table is finished.

The bridge that can be opened at the room entrance has been mounted with two hinges on one side and a sliding lock at the other.

The two ramps are height adjusted and supported to the mm. One has a 2% inclination, the other 3%, we trust trains will be able to drive OK on these.

A few pieces of cork layer still have to be placed and then … let the track laying begin!

This is the link to video Twinwoods & Bedford - 08 - The Table is Ready!

Twinwoods & Bedford - 10 - Turnout Servo Drive

This video shows the servo drive we use on the layout in more detail. The servo motor is an SG90 180°. It fits snugly in a 15mm aluminum U profile, in which two screw holes are drilled as well as a 1mm hole that serves as the pivot point for the pin that moves the turnout. The pin is an unfolded paper clip.

We use Arduino for DCC control, loaded with the MARDEC software that can be downloaded for free from www.arcomora.com. This software is a DCC servo- and accessory decoder and it’s also used to tune the required servo angles for the two turnout positions.

This is the link to video Twinwoods & Bedford - 10 - Turnout Servo Drive

Twinwoods & Bedford - 11 - Laying Flex Track

We use Peco HO 75 track, which consists solely of flex tracks. To lay the flex track we use a couple of helpers like:

• A carton, cut in a circle of the desired radius, to lay circles
• A wire connected to a center pin, to lay circles
• A flexible plastic strip, to mark non circular curves
• A 15mm aluminum U strip, to lay straight track
• Different lengths of hardwood, to lay shorter pieces of straight track
• Track spacing jigs, to lay multi track stretches with high accuracy constant spacing

This is the link to video Twinwoods & Bedford - 11 - Laying Flex Track