Welcome to Fenny Bridge

1:43 scale, 7mm, 'O' Gauge Modern Image Layout,

built by Keith Powell & Steve Weeks.

 

 

 

 

 

 

Board construction

Track plan

Operation

DCC control

Traction

Rolling stock

The future

Latest news

 

 

 

 

 

 

Photography by Chris Perkins

 

The Idea -

It was after Warley 2004 that Keith and I decided to build a 7mm gauge modern image layout together.  With Keith’s attention to detail and many years of modelling experience along with my DCC knowledge / Electrical background we both felt we could achieve something to be pleased with.

 

Planning Criteria -

The layout had to be of exhibition standard, be easily transportable, require no more than 4 operators, have a yard area with operational shunting independent of passenger traffic and be DCC controlled.  The overall length could be no longer than 28 feet as this is the size of Keith’s garage, where the layout would be constructed and used once built.  This would also give easy access for loading and unloading. 

 

Board Construction -

28 feet divides nicely into seven boards measuring 4’ x 18”.  The width allows the layout to be transported in a custom built rack within my van.  The boards are made of plywood frames with reinforced ends.  The bases are 1” thick pink modelfoam available from builders merchants, making them ridged but light weight.  Once complete any cracks were filled and sanded to a smooth finish.  Boards are aligned together using ply dowels and locked in place by over centre catches fitted to the sides.  All boards have tubular metal legs with flat feet which screw to the underside.  Board 4 has four legs and is the first to be erected.  Remaining boards 3,2,1 are joined to the left, 5,6,7 to the right and fitted in that order.  These have two legs only and piggy back one another.  The use of 300mm raised legs means it can be exhibited on standard tables and for use at home, sits on a kitchen worktop in the garage.

 

Track Plan -

 

The track plan, 28' x 18” is of freelance design with hand built track and point work from C & L Components. The bridges, tunnels, platform and retaining walls are scratch built and use embossed plasticard from South Eastern Finecast and Slaters ranges.  Platform and line side accessories are from Peter Clark Models.  The Colour light signals were custom built by Roger Murray (No longer available).

FB Track Diagram.tif

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Operation -

The driving of locomotives is carried out manually by the operator using DCC control, however all route setting and signalling is carried out by a computer.  This combined operation with track occupancy provides prototypical block signalling inc SPAD's, route selection and interlocking. 

 

Computer control -

Having spent many hours learning about signalling and signal box operation I wanted the front end, in our case a laptop, running Traincontroller Gold software to feel and operate very much like a modern signal box but with an early display panel.  This I feel has been achieved by using photographs of actual signal box panels in order to gain graphic representation. 

The Interface between computer and DCC system is LocoBuffer USB 2 from RR-Cirkits.

 

 

Screen shot showing route selection.

A big thank you has to go to Roger Manton for his assistance with our Signalling operations.

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DCC Control -

Both Keith and I had Digitrax systems already and as there was still nothing better in 2004 we decided to stick with it.  The layout is split into three sections called districts DCC/1 to DCC/3.  This separation will reduce in the event of a fault, complete shutdown during an exhibition.  Each district supplies accessory decoders used for the operation of colour light signals and BDL168 (Block detection, for loconet with 16 detection sections and 8 transponder zones) in order to monitor track occupancy.  This information is then fed back to the command station via loconet.   

We have one DCS 100 command station and two DB 150 boosters named Command, Booster 1, Booster 2.  Handsets are DT 400 which offer twin pots for independent control of loco’s with a shared keypad with 12 F keys giving access to functions such as lighting and sound. 

We also have a further DB 150 booster named Booster 3 which only supplies DCC power for the operation of point motors.  For this to happen we use a PM42.  (Power manager, with 4 sections, 2nd version)  This divides the booster output into four sections of which three are called P1, P2, P3.  These supply DCC information and power to DS52 modules which operate Tortoise point motors.   

In the event of a short being caused by an operator not concentrating and driving a loco into a wrongly set point the booster supplying power to the loco will shutdown.  The points however can still be operated without the need to touch the loco as they are fed from Booster 3.  Once the offending point has been operated the booster supplying power to the loco will auto reset and allow the loco to carry on.   

The 4th section is for a service lead with croc clips used mainly for wheel cleaning operations and called S1. 

All programming is carried out on the layout using a siding wired through a double pole change over switch with an ESU Lokprogrammer installed underneath board 1. 

 

Power -

The command station and boosters have a rating of 5 Amps each.  Therefore a 5 Amp transformer is required for each one.  We have used four MT10 from All Components

All DCC Wiring is rated greater than or equal to the max output of the command station or booster.  Cable runs were kept as short as possible to keep volt drop to a minimum. Therefore the cable selected is 1.0 mm squared multistrand and has a rating of 6A.    All cables are distributed from underneath board four, the central location for all power supplies and DCC command station / boosters. This has given trouble free operation.     

DC power is provided from a PC power supply and offers both 5v used for colour light signals and 12v to power the BDL 168.

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Traction -

Locomotives are from the 1980/90 era, without any definitive timeline and operate unassisted at low speed.  All are sound fitted from South West Digital ltd and have working lights.

The answer to the question we have been asked many times "how do you get your loco's to run so smooth".

Although all traction is sound fitted with volumes reduced to give localised sound this has to take 2nd place over running.  After many trials during the last 10yrs only ESU decoders are now used in 128 speed step mode with ABC gears.  This combination with plunger pick ups gives very fine, quiet unassisted control at low speed.  This is because the motor is only driving the gearbox, the gearbox is doing all the hard work.  Track, wheels and pick ups must be kept clean.  Any failure with good house keeping will result in loco's stopping and sound being interrupted. 

Loco's fitted with two motors are wired in series NOT parallel as the decoder back emf is now only controlling one load not two.  This will result in top speed being reduced but the control at the low end is superb.  Parallel wiring will give more top speed but will judder at the low end as the back emf can't control two motors.  One way to achieve both is to order 6v motors not 12v as standard and wire in series.

The above has nothing to do with choice or the cost of a DCC system.  It is all to do with choosing the right decoder for the job, decoder setup, motor / gear ratio and cleanliness.

Locomotive kits 37, 25, 20 are from JLTRT, built and painted by ABC Workshops,  DJH RTR 03, modified by ABC gears, Westdale 108 / 122, built and painted by Dave Hampson, and 31 from MMP, built and painted by Simon Varnam.

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Rolling Stock -
The Wagon & Carriage works brings operational interest with a variety of mixed traffic such as GUVs, VGAs,  Hoppers, tanks and coaches etc being brought in for service and or repair.

There are a mixture of kits mainly JLTRT built and painted by ABC Workshops but also kits from GJH Plant, PRMRP, and Parkside Dundas built and painted by Keith.  There is a rake of tanks from Skytrex and the MK1 coaches are from Easy Build, built and painted by Richard Pogson.

Many hours were spent discussing what coupling to use as shunting would be a large part of the operation and be very visible at exhibitions.  Therefore this had to be automated and very reliable.  For this purpose we chose the Dingham Autocoupler.  These were ordered from Trevor Shaw and duly fitted.  These worked very well as stock could be uncoupled on the move by electro magnet whilst being propelled.  However there were limitations when used with bogied vehicles as the coupling had no sideways movement.

We then had another look at Kadee Couplings and decided to purchase the height gauge and some couplings from      P & H Models in order to convert a few vehicles for testing.  This worked well but again we did not like the fact that each vehicle has to be stopped in order to uncouple it.

At this point in time our heads were rather low and during a moment of madness “out came the Dremel”.  We decided to remove the buck eye from it’s shank and replace it with the Dingham.  This immediately brought a smile to our faces and is now jokingly called the “Kading”.  We now have the best of both worlds with sideways movement and uncoupling on the move.

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Looking to the future -

Visual presentation is very important to us and Exhibitions are viewed like a band would a gig.  We are there to entertain the paying public in a professional manner.

Having completed our maiden voyage without any problems thanks to help from Roger Fithyan, we are recruiting a  fourth member and can now continue our ongoing attention to detail and any improvements felt necessary as they arise.  This will include adding lighting and resistor wheel sets to rolling stock etc. 

I was surprised at the level of interest in computer control form both novice and experienced modellers.  However, over the two days noticed that older people would look at the layout first and then the computer, whereas younger people would do the opposite.  The link with technology is vital, especially for the younger generation to whom the hobby must encourage to survive.

As always we have taken comments on board and in future will not only show the benefits of DCC control to operate trains around the layout, but also include the use of a large screen with a signal box view as part of our overall presentation.

References have been made within the text to companies and individuals that have helped bring Fenny Bridge to life.

We would like to say a special thank you to Caroline for her enthusiasm and putting up with the pair of us.

Steve & Keith

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Latest news -

04/01/2011

See Fenny Bridge at the Nailsea & District MRC show in March

See RM issue 61      Feb 2010 for a full review. 

The Class 20 from Tower has been sold and replaced with a JLTRT version.  Simon Varnham assures me he is well under way with the MMP CL 31, and we now have some Pressflow wagons from JLTRT. Two Heljan 47's are in the workshop along side a Bachmann 08 which is being modified by ABC Gears.

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