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Fen End Pit

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  1. Fen End Pit
    I'm not sure how much more by way of constructional details I can give but here goes.
     
    I started off by making the back of the fiddle yard from 6mm MDF. Two computer rack mount brackets were screwed to the wall. These were originally from Dell PowerEdge servers. If you find a friendly IT department they will probably have some spare as each server comes with new brackets but if you are replacing a server in a 19" rack the chances are there is a set in there already. You will probably find the same thing in the guts of an old filing cabinet.
     
    The MDF back was bolted to the sliding brackets and then the first shelf was stuck at the bottom, strengthened with right angle metal brackets. Foam was glued to the shelf except at the ends where the level was made up with more MDF and a piece of copper clad paxolin. Along one of end of the back a piece of aluminium angle was screwed into which holes were drilled for the bolt.
     
    There are 2 bolts made from K&S tube on each level and these carry the current to each level when selected.
     

    The second to top level is selected, you can see the supporting bolt and the two bolts carrying the power to the track and aligning the rails. The board attached to the fiddle yard is actually removable and sits on a home made right angle bracket screwed to the wall. This board is removed when the layout is not operational to give easier access through the door. The black box with LED is the distance signal for Empire Basin box.
     

    This shows the top of the rack mount bracket and the pulley arrangement for the counter-weight. A pulley wheel attached to the back of the fiddle yard, together with the pulley on the wall, results in the counter-weight moving twice the distance as the fiddle yard and applying twice the weight. The result is that the fiddle yard is still relatively easy to move even when full of stock.
     

    Here you can see the yard aligned to the bottom level. The layers were build one at a time aligning the levels from the adjoining baseboards as I went.
     
    [attachment=10540:2009-11-29 016.jpg
    With the 1st floor level aligned the N7 departs the year with a rack of 3 mk-I coaches. (must get around to fitting the sprung buffers)
     
    The current plan is that the top level will be in the form of 2 Y points joined switch ends together. This will allow me to use the top to reverse a train from UP to Down line and move locomotives around on the fiddleyard.
     
    Having got this far I wish I had been able to make it a little longer, it would have been nice to run longer trains. Even so I can split a train into two halves and use more than one level of the fiddleyard. I think ulitmately I will have some coaches which sit on the top level and join a train in alternate directions. The other intention for the layout is that a pick-up goods will arrive and be shunted into the loop before wagons are tripped down to the quayside basin for unloading. This way I get the combined enjoyment of watching the trains go by and a hidious shunting puzzle.
     
    Thanks for all the nice comments.
     
    David
  2. Fen End Pit
    Over the last few months I've been working on a cunning plan to add interlocking to my lever frame. The frame itself is from the Shropshire and Herefordshire Area Group sold through the Scalefour stores. The frame is connected to a MERG CANACE3 circuit board so that each level generates a different event on the MERG CBUS. This means that the only thing coming out of the frame to the layout is the 12v and 0v power lines and the CANH and CANL data wires of the CAN bus.
     

     
    This has been fitted with a small modification in the form of a strip of nickel silver soldered into the bottom of each lever made from scrap from the etch. This 'tail' sticks out of the bottom of the frame.
     

     
    The locking is provided by means of a small servo under each lever which is fitted with a brass collar. The collar rotates to either lock the tail of the lever on one side or the other or present a slot through which the tail can pass.
     

     
    The servos are driven using MERG CANACC8 boards configured with the new CANServo8 code. Last in the box is a MERG CAN-USB board which allows the CBUS to talk to a PC.
     

     
    The PC runs the PanelPro from the open source JMRI project. Without going into too much detail (unless people want to know more) the levers are each defined as a 'Sensor', the turnouts on the layout and the servos which control the locks are defined as 'Turnouts'. I have set the CBUS boards on the layout which drive the points and signals to respond to the events direct from the lever frame so that I don't need to connect the PC. However when the PC is connected the 'Logix' programming in JMRI is configured so that each locking servo is set depending on the state of the levers.
     
    The great virtue of this system is that I can program all the locking on the PC and change it easily if (when?) I get it wrong. In practice so far I have got about half the locks working (there is some alignment work to do between the tails and locking rings) but have demonstrated I can make the distance signal only be released when the relevant home and starters are cleared. Also I can show that clearing the distance signal locks the homes and starters clear. In simple terms each lock has two conditional actions applied, one which unlocks the lever when A normal and B normal and C reversed etc. and a second which locks the lever when A reversed or B reversed or C normal etc.
     
    I could even get silly and add some train detection by track circuiting and then interlocking with that, or even only allow the starter to be cleared when I have a line clear from the box in advance.... or may implement locking that allows me to only pull the starter once per line clear.... This way madness lies.
     
    David
  3. Fen End Pit
    Over the last week I've been experimenting with my MERG CBUS components and JMRI with a view to producing a way to make a mechanical signal box frame which is interlocked and interfaced with a PC. The requirements I've set for myself are as follows:-

    I want a mechanical lever frame, with proper chunky levers to pull. I've already build one from the Scalefour stores produced by the Shropshire & Herefordshire Area Group (######).
    I want the frame to prevent me from setting conflicting routes, basically I want prototypical interlocking of the levers.
    I'd like to be able to change the interlocking easily if I make a mistake when I define it, I'd rather not have to re-file the notches on a load of mechanical locking bars.
    I'd like to be able to run the layout without having to have a PC on, but are prepared to only have the interlocking working with a PC connected.

    The plan is to use a simple electro-mechanical locking bar on the frame which will be unlocked if the lever to be pulled should be free. In simple terms each lever features two micro-switches:
     

    The first which is off when the lever is normal and on when it is reversed.
    The second is on the catch handle of the lever and is on when the handle is pulled, indicating that this is the lever which the signalman wants to change.

    In basic operation the signalman pulls a catch handle on a lever which sends out a signal saying 'I want to pull lever no. X'. The software on the PC then works out if lever X is free based on the position of all the other levers and if appropriate removed the lock from the frame. As I'm not trying to achieve HMRI levels of safety I'm OK with the entire frame being locked/unlocked with a single bar. There is obviously a risk that the signalman pulls the catch handle on an unlocked lever, unlocks the frame and then pulls a completely different lever but I'm probably going to live with that limitation in safety.
     
     
    From my experiments with CBUS and JMRI I've now been able to make the basic idea work. I'm sure there may be other better ways to do this so I'll be interested in any feedback from experienced JMRI users. One thing I've found from playing with JMRI is that the British approach to signaling isn't necessarily the way JMRI (or certainly most of the documentation) is written. I'm hoping what I've done will make some more sense to British modellers.
     
    For my demo board I had my levers with one switch on the lever and one on the catch handle and a number of outputs which will ultimately be linked to servos. At present I haven't implemented the locking bar and am just showing a light when the frame is locked. However I'm confident that this will be relatively easy to implement.
     
    Training the CBUS boards
     
    The first step was to train the CBUS output board (CANACC8) to respond to the relevant events on the CBUS consumer board (CANACE8c). This is basically a case of selecting the output you want to train, then sending the signal which you want it to respond too. All pretty straight-forward and explained in the relevant MERG CBUS documentation. The result of this is that pulling lever 1 makes output 1 change, lever 2 makes output 2 change etc. I used 4 events on the CANACE8c to the the turnouts and 4 to be the catch handles. Ultimately the events from the catch handles don't need to have any corresponding actions on the CBUS hardware as their only use is in telling the PC which lever is trying to be pulled.
     
    Starting with JMRI
     
    Having got the test rig so that levers and catch handles on the frame made appropriate outputs on the consumer board the next step was to link it up to the PC using the CAM-USB. I download and installed JMRI and started it up, telling it that it was connected to the layout via MERG-CBUS. This worked fine and when I select CBUS console I could see events from the switches being displayed.
     

     
    The next step is to define the turnouts, adding the name of the CBUS event which changes the point and giving it a meaningful User Name, I made the User Name include the type and lever number of the for simplicity of understanding later e.g. turnout2, home1. Having selected that the turnout is a MERG controlled turnout the system code is sent for you a MTxxxxx, the format being +N{node #}E{event #}.
     

     
    You have to put an entry in the turnout table for both turnouts and signals so here we have defined that there is a signal I'm calling 'shunt4' and it is changed by sending a CBUS event node 1 event 4. The complete turnout table, with 4 levers and a 'turnout' which will be my locking bar eventually looks like this.
     

     
    Next I needed to define a signal, and this is where the American nature of some of JMRI's documentation caused me some head scratching. When adding a signal you make up a system name of the form MHxxx, I decided to make xxx the lever number on the frame for consistency.
     

     
    The User Name has to be the User Name defined in the turnout table. The completed signal table looks like this. By clicking on the 'state' button we can change our signal from red to green.
     

     
    Next I put the first two elements, home1 and turnout2 onto a simple layout diagram. (I found an icon for a home signal I liked but these are pretty straightforward to change as they are just .GIFs)
     

     
    At this stage clicking on the turnout or the signal changes the light representing it on the test rig because the PC sends out the appropriate CBUS event. The lever also changes the light but this change is NOT reflected on the diagram on the PC (and obviously changing on the PC doesn't change the lever on the test rig)
     
    In order to get the PC to see the change in state of the lever I define a sensor using the same CBUS node/event as the for the turnout table. Again I gave a User Name based on the number of the lever with the intention of hopefully keeping things consistent and easy to follow later on.
     

     
    Now what I needed to do was make a change in the sensor on a lever also change the state of the object in JMRI. A side effect of this is that the PC will then send the same CBUS event out, effectively duplicating the message to the accessory, but this doesn't appear to be a problem. The way this is done is to define 'logix' in JMRI. For each lever I define a two rules, one that says when you see the sensor on the lever go active you set the turnout to reversed and the other which puts the turnout back normal when you see the sensor for inactive.
     


     
    Having created this logic the lever on the test rig now changes the light representing the accessory and the relevant symbol on the layout diagram in JMRI. I drew some suitable GIFs to show a lever normal and reversed in various colours to match a lever frame.
     

     
    Defining some locking
     
    Now want I wanted to do was use a sensor on the lever's catch handle to workout if the locking bar could be moved. You will see on the layout diagram above a little green dot indicating the catch handle on the lever is normal (i.e. not pulled). What needs to be defined is two (or maybe three) rules that define what actions happen with the catch handle sensor.
     
    The first rule, which will be the same for all catch handles is to restore the lock after the catch is released.
     

     
    The second rule is the one which does the work, this removes the locking bar when the catch handle is pulled, but only when the other turnout/signal/sensors are set correctly.
     

     
    In this example you the locking is only removed on signal 1 if sensor 2 is inactive, in other words lever 2 reversed locks lever 1 or the home signal can only be pulled off if the turnout is set for the straight, normal, route. Obviously a matching rule to lock the point if the signal is clear needs to be applied to the catch handle on turnout2.
     

     
    Finally I used the icon for a Scissors crossover icon to show on the diagram if the locking bar is locked or unlocked (when the crossing over route is shown it means unlocked)
     


     
    The Third set of rules will be needed for levers which are locked in reverse as well as normal.
     
    Conclusions
     
    Well the basic components are there to allow me to build my electro-mechanically interlocked frame. The 'Logix' part of JMRI seems to be comprehensive enough to cope with most forms of locking. The hardest part is going from the logic you usually think of when doing locking (lever 2 locked by lever 1) in terms of what is released by what (level 1 released by 2 normal).
     
    I'm sure there must be many alternative ways of achieving what I done, I'd really like to hear your suggestions.
     
    David Barham
  4. Fen End Pit

    MERG DCC system

    By Fen End Pit,

    I thought folks might be interested in a couple of photographs of the new MERG CBUS based DCC system. This uses a CANBUS (originally developed for the automotive industry) to transmit the signals from the handset to the command station which then generates the completely standard DCC signals on the track. The advantage is that this is the same wiring bus as I using for controlling the rest of the layout using other MERG CBUS boards. Ultimately I should be able to run the whole layout with 6 to 8 wires between the boards.
    Two for the DCC signal.
    Two for the CBUS.
    Two for a 12v DC pair to power the modules.
    I'll probably end up with another pair for a 16AC as this can then be used if I need power anywhere else.

    There are three components to the DCC system, A command station which is a simple PCB costing around £25 to build, a number of handsets which are available as a kit for £38 and a soon to be released booster which will be another ~£25. Without the booster you are limited to pulling about 1.5amps in total but that is proving adequate to run a couple of trains around Empire Basin with no problems.
     
     
    The command station is pretty straight-forward to build being just a single board and convention 'through hole' mounting of components. As usually you need to take some care with your soldering and reading the instructions but it isn't beyond the skills of a beginner.
     

     
    The handset on the other hand is a good deal more complex requiring the use of surface mount components. These look a bit scary to start off with and I watched several video clips on Youtube demonstrating how to solder a chip with 20 pins down one side an inch long onto a board with trepidation before having a go. In the end I found it wasn't as bad as I feared, a combination of a circuit board covered with a solder resistant surface (except that is where you need to solder!) and the smallest soldering iron bit Maplins had did the trick. I also bought some de-soldering wick which came in handy on the occasion when I did manage to bridge a connection. In the end the little handset really does feel like a quality part and is a credit to those involved with the design. The knob is positioned nicely for the thumb and you can easily drive the loco with one hand. The push buttons are very easy to work and the typical operations of selecting a loco or turning a function on and off are all quite logically and take very little getting used to. There are a couple of limitations with the current version of the firmware around taking control of a loco already assigned to another handset but these are all developments due in forthcoming releases.
     

     
    A combination of the MERG command station, the CAN-USB interface which allows a PC to talk to the CBUS and the Java Model Railway Interface (JMRI) also allows the use of an Android phone or (if you want to sell your soul to Apple) a Iphone as a throttle. I'm tempted, but not tempted enough to want to part with the cost of a loco kit just to try it!
     
    David
  5. Fen End Pit
    Back in the early 90's I drove up into the wilds of the Fens and found a few remnants of the Wissington Railway. The photos came to light again as I was sorting out my drawers so I thought I'd share them.
     

     
    Turning off the A10 north of Southery and you could still find the remains of rails in some of the concreted field entrances.
     

     
    In other places you just had to imagine where the railway once went along the size of the drain.
     

     
    Here the railway once ran between the concreted road and the trees.
     

     
    Some of the concrete sleeps have found a new use in a farm yard.
     

     
    This bridge was at Little Ouse I believe (just up the road from Shippea Hill) and now beyond the security gates installed by the farmer giant agri-business.
     

     
    This wonderful old feedmill is on the road from Prickwillow to Shippea Hill. It was an essay in corrugated asbestos which has now been rebuilt beyond all recognition into a house.
     
    It would be incredible difficult to model the Wissington lines. Rails almost completely hidden by vegetation, ridiculously tight curves and the problem of needing to a baseboard about 200 metres square before you could find anything to use as a scenic break.
     
    Go on someone, prove me wrong.
     
    David
  6. Fen End Pit
    I've made a lot of progress with the Ruston over the weekend. I decided to build the locomotive using 'split axles' for the pick-ups.I decide to try something new here and use the delrin gear as the space to keep the two parts of the axle aligned. The gears are about 8mm wide so each end of the axle is pushed into the gear by about 4mm. A little circle punched from a piece of thin paper is enough to keep the ends electrically separate and the whole lot is flooded with loctite so hopefully it won't move. You can also see in this picture the shorting strips on the wheels which are from Brassmasters. I know the wheels are really too 'thin' for 16mm but having fitted all the rest of the stock with O gauge profile wheels, and built the point work on Fen End Pit to the same standards I have to stick with it really.
     

     
    Firstly I tried running the loco up and down just on DC power. I had to take a fibre glass brush to the wheel treads to remove most of the chemical blackening but after doing this it ran up and down. I benefits from some added weight but there is plenty of room for added lead later.
     

     
    Yesterday was spend in the not very photogenic activity of trying to fit the DCC chips, sound chip, stay-alive capacitor and speaker. The cab has a useful space, formed of a large ballast weight and a locker which gives a useful space for the chips. The speaker is set under the bonnet.
     
    The results can be judged in this youtube clip
     

     
    Today I've been adding more etched bits and some more details in plasticard. I also annealed and bent up the tractor seat, which I'm rather pleased with.
     

     

     
    Next up I have a load of work on the cab interior to do.
     
    David
  7. Fen End Pit
    I thought I'd put up a few pictures of Empire Basin, my bit of East London in P4.
     
    David
     
     

     
    This is the view from the door to the spare room. The minimum radius is down to about 40". It is rather nice to sit on the PC while trains go round and round.
     

     
    The fiddle yard is vertical but only 1 metre long. The unit moves on brackets designed for rack-mounting computers and is counter balanced by a large lump of MDF.
     

     
    The Riceworks J65 sits on the loop with a brake van in front of the Scalescene's factory.
     

     
    A Bachmann 24 hauls a train of vans on the main line.
  8. Fen End Pit
    The 1.5mm MDF I ordered arrived today, the 1mm was out of stock. 1.5mm is the same thickness as the width of a header in 4mm so this allows me to interlock the walls on the header joint. I deliberately drew the 'tab' of the header .2mm over length to get around the problem I had previously that the 'tab' was not quite long enough to lie flush with the 'slot' when the wall was put together.
     

     
    I also cut a piece of the MDF to be a sanding jig. By putting the wall through the jig I could lightly sand the ends of the 'tabs' to remove the charring from the MDF and get them exactly the right length for thickness of wall. All that is needed is a couple of strokes over some sandpaper. Obviously the MDF jig gets a bit thinner each time but I'll cut another one for the next building so it only has to be used 8 times before it is discarded.
     

     
    The resulting edge doesn't then show up as a wildly different colour to the main walls which I hope will make painting easier.
     

     
    A piece of 3mm MDF was cut to form a central core for the building. I'm hoping that 2 laminations rather than 3 won't be a problem given the sizes involved.
     

     
    Again the building slotted together perfectly and sat down into its base. This picture is without any glue holding it together which is why the tops of the walls have a slight gap.
     

     
    The 3mm inner core is cut with some larger rebates around the windows so that I can fit some glazing in later.
     

     
    Now to glue it up and paint it, must be more patient this time and apply more, thinner, layers of primer and let them harden properly before trying to get the mortar layer on with the acrylic. Mind you, it doesn't look like the weather for being in the garage with an aerosol.
     
    David
  9. Fen End Pit
    I was luck enough to have the opportunity to get hold of a pile of original Airfix 16 ton mineral wagons. Nice little kits which are worth a bit of work to bring up to modern standards. The price seems quite reasonable too!
     

     
    I wanted to use Bill Bedford sprung W-irons so first thing was to remove the plastic W-irons to just leave the spring and axle boxes. i was actually surprised that this wasn't more difficult than it proved to be. I started off with a razor saw and then finished off with a file and an emery board.
     

     
    The assembled W-iron frames were stuck on to the floor of the wagon using araldite and a Brassmasters Jig. If you don't have one of these yet and you build wagon kits get one, they are indispensable.
     

     
    This gives a nice square rolling chassis which has a smooth ride on the spring steel wire springs.
     

     
    Next up was to work on the brake gear, rather than just replace the lot with brass I decided to se what I could do to improve the original plastic castings. I filed the back of the safety loop and then stuck a piece of plasticard on the back so that it looks like a loop rather than a solid block.
     
    On a similar vein I hollowed out the brake handle catch. I started off with a drilled hole and then opened it up a piecing saw and a little work with scapel.
     

     
    Putting it all together and we have a pretty decide chassis. Next step will be to work on the bodies, and the other six I got to build!
     

     
    David
  10. Fen End Pit
    Great to have RMweb back after the Christmas downtime - thanks to Andy for seeing it through.
     
    I decided that I needed to redo the control for the lower section of Empire Basin to use servos. This is partly because I was unhappy with my attempts at wire-in-tube and the rather lashed up linkages I'd made which didn't work very well and partly because I wanted to have a test bed to demonstrate the use of servos for point control.
     
    I needed to make a proper drive mechanism for the point blades which allows for some adjustment in the blades when fitting them to the layout, I also wanted to separate the servo component from the TOU to allow for easier fitting. The use of servos makes for much easier fitting as the adjustment can be made on the servo controller rather than having to fiddle with different lengths of linkages.
     
    In the past I've made TOUs out of brass and paxolin but decided to try using plasticard for this project. The Plastruct square tube is pretty robust stuff and when stuck onto layers of 60 thou plasticard make a component which I think will be strong enough for last.
     
    I cut two lengths of plastruct tube which telescope together, the larger is 5/16th inch and the smaller 1/4 inch. These were cut 50mm and 55mm long respectively.
     

     
    Starting with the larger tube I drilled two pilot holes 16mm apart (for P4, EM or OO would be closer) and then slowly openned the holes up to 6mm in 1mm stages. The larger tube was then stuck on to a base plate made of two pieces of 60thou plasticard which gives a base almost 3mm thick. This base blade was then drilled through the same 6mm holes. At the same time I drilled some 3mm mounting holes in the base plate (only done on the front one in the picture).
     

     
    The unit connects up to the point blades via lengths of 16th inch tube which have a length of .8mm brass wire fed through them. The wire gets soldered to the point blade and the adjustment in height can be managed by moving the wire up and down in the tube. I drilled the holes in the smaller of the two plastruct tubes 1.5mm and then openned them out to be a force fit for the 16th tube. The brass tube is around 40mm long and is pushed through the smaller section plastruct once it is slid inside the larger tube. For my depth of base board and underlay I ended up with 11mm of tube protruding above the base. It is worth remembering at this stage to put a broach into the end of the brass tube to remove the burr from where it has been cut, this makes pushing the wire through later a lot easier.
     

     
    To make sure the tube doesn't move I mixed up some aruldite and pushed it into the smaller of the two plastruct tubes and around the brass tube. This should secure things but also avoids the risk of sticking the whole thing up solid which I thought might happen if I tried applying superglue from the outside.
     

     
    Finally I stuck and shaped an operating wire connection by laminating three little bits of 60thou together and sticking them into the inside of the sliding section of tube. This is drilled with a .8mm hole which will have the operating wire threaded through it. A little bit of tidying up with some sandpaper and we have a pair of complete TOUs ready for installation.
     

     
    The holder for the servo is even simpler, base plate of two 40mm square pieces of 60thou and then 'walls' of 60thou 12mm high cut to go around the servo. I drilled these walls with a pair of 2mm holes which allow the servo to be securely fastened by simply threading a short length of 2mm rod through the mounting holes on the servo case.
     

     
    The result is a unit which I can screw to the baseboard but from which the servo can be removed without too much problem. These servos are TowerPro SG-50s which cost about 3 pounds each depending on where you buy them. I got mine from 'Giantcod.co.uk'.
     

     
    So with these components ready to mount it is time to fasten them to the base board.
     
    David
  11. Fen End Pit
    Over the last week or so I've been inspired by an article in the MERG magazine to have a go with an Arduino. These little micro-controllers are ridiculously cheap and can be programmed to do all kinds of things. I've chosen to control a couple of stepper motors to make a pair of level crossing gates.
     

     
     
     
    David
  12. Fen End Pit
    Over the last few weeks I've been drawing up a laser cutting drawing for a Great Eastern Railway '1865' style building. These were built on several lines including the Stour valley line, conveniently these came in three sizes, small, medium and large. The Great Eastern Railway society publish some plans of the small version Takeley and an ancient April 1986 copy of Practical Model Railways has drawings of the Medium taken from Lavenham.
     
    I've decided to try this as an experiment on cutting using Acrylic rather than MDF. I had some white 3mm Acrylic and I obtain some .7mm Acrylic/ABS mix from HPC laser.
     

     
    Just the base here cut from 3mm Acrylic. It worked ok and the joints seem very strong with Plastic Weld. I've tried using a mitre joint on the small shed end of the building using the sanding disk in Makespace. I had to use a little model filler on the corners but I think the corners might look better than the 'interlocking' method but we'll see once it is painted.
     

     
    The building has brick adornments on the corners and around the windows and here I've tried using the .7mm material from HPC laser. This isn't listed on their website but you can ask for it if you ring them. The material cuts a lot better than pure ABS and I can see that it has potential.
     

     
    Once I stuck the quoins onto the base it does begin to look like an 1865 station building.
     
    I think I need to practice a bit with some of the strengths/speeds of the laser to get the brick engraving and cutting better but as an experiment in what the materials can do I'm happy so far.
     
    David
  13. Fen End Pit
    I made a start on the etched chassis for the Slater's simplex. The etch is quite thick material so a little filing needed to remove tabs and cusp. Very pleased with how well the parts fitted. A fair amount of heat was needed to get the solder to flow but the resulting chassis is strong and square.
     

     
    The horn guides are cleverly made from the etched parts and form a slot which allows the horn block to move vertically. Again the fit the very good just requiring a few strokes with a file to get a smooth vertical movement with no horizontal wobble.
     

     
    The parts for the brake gear also got attached at this point, the pull rod, complete with turn-buckle is just located in the castings at the moment, the instructions suggest not fitting permanently until the wheels the in place.
     

     
    Next step involves sprung plunger pickups.... I'm enjoying this.
     
    I'm starting to consider the possibility of putting a sound chip in this. Trying to find a Simplex sound is hard but what do you think to this one?
    http://www.d-i-e-t-z.de/jd/mp3/micro/klanzh.mp3
     
    David
  14. Fen End Pit
    A Bank holiday seemed like a good time to do a bit of building work and finish off the roof of the big warehouse behind the viaduct. The Brassmasters etchings made the northlight units quite rigid though cutting them all to a different length to match the profile of the backscene was a bit of a faff. I had decided that one end of the building would house the lift shaft so this got a block house on top to house the lift mechanism.
     

     
    From track level the building now looks quite impressive. I still need to add some pipework etc which will hide the joint between the front and side sections.
     

     
    David
  15. Fen End Pit
    My model of Thaxted water tower is coming on nicely. As I commented in my last blog I cut a base for the tank from 3mm acrylic (an alarming orange colour) and a pair of formers from transparent acrylic. A piece of brass the right height was then folded around the formers and stuck on with epoxy.
     
    I think the painting was much more successful than previous attempts. I had sealed the MDF with an MDF sealing paint and then sprayed on two coats of red oxide primer, leaving a good bit of drying time between the two coats. The first coat was still absorbed into the MDF in spite of the sealer but then the second actually dried to a decent surface. When really dry I used ModelMates Brick Joint Filler, leaving this to dry as per the instructions before wiping it off with a damp kitchen towel. The resulting mortar is way too white so I toned the whole thing down with some black water colour washes. I have since experimented and you can add a touch of water colour to the ModelMates paint prior to painting it on which takes the bright white look off quite well.
     

     
    I improved the corners slightly after this photograph by using some filler to fill some of the slight gabs which were present where the sides mated. This improved the fit of the corners and makes them look better. Again a wash of black/brown water colour paint was applied. The tank was primed, then sanded and filled before a second coat of primer and finally a grey enamel sprayed on. I also primed and sprayed the windows and door in what I hope is a suitable colour.
     
    The photo shows the tank placed on the base, the two long pieces of wire will get chopped off once I have fitted a piece of of transparent acrylic as the water. I think I going to paint the underside of this a dark colour rather than have you being able to see the bottom of the tank. I've also bought some plastruct angle and T section (the tiny ones ~1mm in section) which I plane to use to make some kind of internal supports around the top of the tank. If nothing else it need some kind of tie structure to stop the sides from bowing out with the weight of the water.
     

     
    To be honest I'm really rather pleased with the way this is looking, All I need now is the spare room to recover from the smell of the bottle of thinners I knocked over while painting!
     
    David
  16. Fen End Pit
    As requested a few more pictures of Fen End Pit.
     
    The drag line is scratch built based on plans from a Ruston Bucyrus works manual I was given by a friend.
     
    First up a view of the entrance to the works as a Simplex 40S arrives with a train of sand from the pit.
     

     
    This is a view of the entire unloading end showing the tipping dock, unloading conveyor and the storage silos.
     

     
    And finally a shot of the unloading hopper with a skip just tipped.
     

     
    Hope you like them.
     
    David
  17. Fen End Pit
    Having worked on repairing my Lister thoughts have  turned to building a new locomotive for Fen End Pit. I'd rather taken a fancy to the tiny battery electric locomotives built by the likes of Wingrove and Rogers and I thought that one of these engines might be worth trying to 3D print. A recent video in the 'Lawrie goes Loco'  series on Youtube also rather drove my project along.
     
     
    There are some superb plans available on Flickr from J. Tilston. I purchased a number of his drawings on CD which used to be sold under the 'Industrial Narrow Gauge Illustrated' name back in the early 2000's. I tried to contact the email address a few weeks back to see if any more were ever produced but have got no reply. Does anyone know what happened to them?
     
    The drawings allowed my to produce a, hopefully reasonably accurate, 3D model of the loco broken down into parts which I thought I could print on my resin Phrozen Sonic Mini 4K.
     

    To give you some idea of the diminutive size of this little critter the 'footplate' was designed to fold up reducing the total length of the locomotive to four feet so it could be lowered down a mine shaft. The wheelbase is the same as a gauge, 32mm in my 16mm:1' scale. The wheels match the diameter of O gauge lowmac wheels. The first attempt to print all the bits took just under 3 hours and came out pretty well - the seat failed to print because I had not really got the supports right and some minor changes were made to the model to sort out the fit and clearances.
     

     
    I painted the battery box from this batch of printing as it came out well enough to use. I'll probably make some spares of this part and also the slightly different version with a 'peaked roof'.  The main chassis is printed in a single part and includes recesses into which four 'High Level' etched hornblock guides can be installed. These were fitted after the assembly of the coupling rods and jigged using the 'rod with a taper on each end' jigs for 1/8" axles I use for Scalefour locomotive construction. I'm still undecided as to whether I'm going to need to work out a method of springing the axles or adding a compensation beam on the front axle or whether this will be unnecessary.
     

     
    The O Gauge lowmac wheels obviously don't have crank pins for coupling rods and are also rather skinny so I tried printing some overlays to go on the front of the wheels. These included a 1.75mm hole in the centre for the end of the axle and a hole into which an Alan Gibson crank pin bolt would self-tap. The actual front edge of the wheel overhangs the rail by quite a margin so I'm hoping I can stick the overlay in place, fill the gap between the overlay and the wheel itself and get away with it!
     
    The rods are just held in place by some wire insulation at the moment. 
     

     
    I've 3D printed the coupling rods and bushed the holes in them with some brass tube. I suspect that in the end I might resort to getting these etched though. They are surprisingly strong in resin but I think metal would be a better choice for long term use.
     
     
     

     
    Ultimately the crank pin bolts will be cut short, proper crank pin nuts installed and then the crank pin covers stuck over them. These covers printed rather well given that they are only  about 6mm in diameter, you can see the bolts and the grease nipple quite clearly. Again, for this test I just used a .05mm layer height, I will probably reprint at .03 for the final version.
     

     
    The wheels (or more accurately the overlays) were quartered by eye and the loco seems to roll along quite happily without binding. The plan for motorizing is to try an N20 type motor for the first time, I've got a pair of the '100 rpm' versions but I'm waiting on a slow boat from China for some bevel gears. The motor is intended to sit in a cradle built into the chassis and there is a cover which will (hopefully) hide the gears from Fen End Pit's sand and make the unit look more like the actual motor which was installed between the frames. (Picture below was version 1) of the frame print before some minor tweaks were added.
     
     
     
    Work on this project will probably pause now until the bevel gears arrive but I'm happy with the progress so far. I am still working on how to manage the power pick up as this locomotive will be powered from the rails as per the rest of Fen End Pit's locomotives. Fitting a DCC chip and stay-alive won't be an issue was the battery box is a very convenient space for them. I'm tempted to try and work out how to split the axles, I think I need to work out how to make some 1/8" internal diameter plastic 'muffs' to go around the axles. This would allow me to just connect some wires to the horn-guides and add some Brassmaster's shorting etches to the back of the wheels.
     
    For now, here are some pictures of the parts, loosely assembled into the shape of the completed locomotive.
     

     
     
     

     

     
    I will admit that I am really rather looking forward to seeing if I can actually make this run. I'm sure it will involve more work and printing - I can see the parts which don't make it being added the end of the Fen End Pit scrap siding, slowly disappearing under the undergrowth...
     
    David
     

  18. Fen End Pit
    Friday night saw the ends of the Wickham trolley assembled and then Saturday saw the roof bent to shape and the parts soldered together. At the moment everything is just resting together but you get the general idea. The wires sticking out the front are to the motor.
     

     
    The plan is to stick a DCC chip under the roof and run the four wires up the each of the corner posts, the power from the track up the rear posts and the drive back to the motor down the front ones. The seats were mighty fiddly but the effect of not having the trolley filled with mechanism is rather nice.
     
    I also did a bit of drawing, followed by some laser cutting this lunchtime. The result is a prototype under baseboard turnout operating unit. The idea of the design is that the brass tubes stick up through the baseboard and have a wire attached to the switch blade threaded through them. The drawing needs a bit of fine tuning to get the holes a nice tight fit but the basic principle seems good and very easy to put together.
     

     
    Let me know what you think..
     
    David
  19. Fen End Pit
    When Hornby announced that they were producing a J15 I was very happy. A favourite locomotive read-to-run and an excuse to get a second to go along side my kit build model Alan Gibson.
     
    Edit 16/8/19 - Work on the J15 EasiChas has now made progress see later blog entry here https://www.rmweb.co.uk/community/index.php?/blogs/entry/22523-j15-chassis-kit-design/
     

     
    Initial inspection gave the impression of a nicely made model but the more I looked at it the more I felt disappointed. What on earth made them get the handrails so wrong! Instead of the handrail knobs sticking out of the boiler at the perpendicular they were horizontal. For no apparent reason someone had decided in the design process to add completely erroneous little mounting points on the boiler and then make the handrail knobs stick out of them horizontally. I can't even see a manufacturing reason for making this design choice, why would the boiler be easier/cheaper to make with the holes horizontal? It doesn't seem to be a mistake which has occurred on other similar models in the Hornby range.
     

     
    I just couldn't satisfy myself that 'it looked alright' and so the locomotive has sat in the drawer for over a year while I wondered what to do about it. The problem was how to re-drill the holes for the knobs in the right place and at the right angle in Mazak, which is horrible material to drill. I clearly needed some kind of jig, but it would have to be a complicated shape to hold a drill at the right angle. Using a combination of measurements from the works drawing which I had from the Gibson kit and measurements from the Hornby model I came up with a shape which could be bolted over the footplate which holds a brass tube at the correct angle. The opposite side of the jig is also angled so, when you put it on the bench the hole to drill is vertical.
     

     
    The two parts are held together by a pair of M4 bolts and the 3D printed material is strong yet soft enough not to damage the foot plate when clamped together.
     

     
    The original handrail was removed carefully and it was clear that it was a very nicely made unit. The knobs are pretty much scale and it can be reused as is. It took a little effort to pull it out from the boiler but a little bit of card to protect the boiler followed by using a scalpel blade as lever go it off without damaging either the rail or the boiler. Filing off the support 'bumps' was harder as several of them are quite near detail such as the washout plugs which you want to retain.
     
    The positioning along the boiler was done with a set of vernier calipers, measuring the distance from the front of the cab to the handrail hole and the subtracting half the width of the jig.
     

     
    Drilling was horrible. The Mazak is a very hard material and I only had some nasty cheap .5mm drill bits. After several hours (and several broken bits!) I swapped to a decent Carbon Steel .45 drill bit from Eileen's Emporium and things became much easier. The hole which I'd 3D printed in the jig for the drill was sleeved with a short length of 1mm external - .5mm internal tube. Once I'd drill the initial pilot hole the piece of brass tube was removed and the holes enlarged to .75mm to take the handrail knobs. A little bit of filling was required on the original holes.
     

     

     
    With the handrail back in place I've just brush painted a little black on to cover up the work, the finish is better than the photo makes it look but I'll get the airbrush out to tone things down and blend the finishes together a bit more once the chassis has been rewheeled. To my eyes the handrail just looks so much better and I'm very pleased that it is still horizontal and in the right position vertically. (it lines up with the one on the cab side) and the boiler looks better without the extra mounting points which never existed on the prototype.
     

     
    I've purchased a conversion set from Alan Gibson to rewheel to Scalefour, There is a good guide to this on the Alan Gibson site at http://www.alangibsonworkshop.com/Hornby%20J15%20Conversion.pdf I'm not sure at the moment whether I can bush out the crankpin holes or if I would be better of drawing up and etching a new set of rods.
     
    Don't expect any rapid progress, but at least now I have the handrails sorted I can feel it is worthwhile.
     
    David
     
    Footnote - I apologise to all of you who have Hornby J15s and have been trying to convince yourselves that the handrails are ok
     
     
  20. Fen End Pit
    *This is the standing joke in my house when model railways become just too difficult.
     
    I'm in the dumps as no matter what I try I just can't get a brick finish I'm happy with, I can see now why I stuck to using Scalescenes for so long, I just can't paint brickwork.
     
    The desk is covered with dozens of little laser cut test sheds which are going to end up in the bin very soon at this rate.
     

     
    I've tried painting a brick colour in Enamel and using an Acrylic to run the mortar into the cracks. I've tried painting the whole building in a mortar colour and then painting the bricks using a sponge pad. I'm incapable of picking out individual bricks i just end up with painty blobs and I don't seem to be able to get enough of the 'mortar wash' off the surface of the bricks (using water or IPA) to bring it back to a decent colour.
     

     

     
    I'll admit to feeling right royally hacked off with it.
     
    HELP!
     
    David
     
    edit :- feeling better already
     

  21. Fen End Pit

    Fitting TOUs

    By Fen End Pit,

    I spent a few hours today fitting the TOUs and servos which I built yesterday. I'm hoping a step by step guide might be useful to some people.
     
    The first step is to drill the holes which the TOU will go through to connect to the switch blades. If you are sensible and have planned ahead you will of course have drilled these before you stuck the point down or at least before you fitted the rails! However all is not lost as you can carefully drill a couple of pilot holes in the right place about 5mm from the end of the switch blade. Having drilled these I then VERYCAREFULLY opened the holes out to 8mm in several stages, making sure that the drill bit didn't go to far and touch the rails! A decent electric drill helped here (good to know I got something useful for working with my current employer for 5 years!). Designing the bracing on the board so it won't foul the TOU is obviously a must (spot the deliberate mistake).
     

     
    The TOU and servo mount were positioned under the board, It is a bit tricky to see both sides of the board at once and I found that putting some double sided tape on the units helped me stick them to the board while then allowing me to adjust a bit. It provides enough hold to them allow me to get a pilot hole drilled prior to putting the screws in.
     

     
    Then the length of .8mm brass wire can be bent up. I usually go for a short right angle bend and then bend that slightly to one side so that the short section will sit into the web of the bull-head rail. The wire can then be threaded down through the brass tube and soldered to the rail. Once both sides are done the TOU should move the blades smoothly. There is space for a little bit of tweaking if the blades aren't quite the right distance apart, the tube will take a little bend if you need 1/2mm of extra or less movement.
     

     
    Next job is to link the TOU to the servo, and this is where the real advantage of the servo comes into play. Because you can adjust the throw so easily you don't have to fiddle about making the linkage exactly the right length. I simply made a short length of steel wire by eye the distance from the hole in the TOU operating arm to the centre of the servo drive. Then I fitted one of the smallest servo arms (the servos have a variety of shapes and sizes supplied) and threaded the wire linkage between the two units.
     

     
    The downside of servos of course is that they need some electronics to make them work, but the 4 servo unit produced by the MERG (called a Servo4) is very easy to build and cheap at GBP 5.50. This unit has 4 double-pole-double-throw switches connected to it, one pole switching the frog polarity and the other switching the input on the Servo4. To set the board up you can either build and use the purpose built programmer which the MERG sell (probably a good idea to get one to take to exhibitions if you need to do any adjustment) or use a serial cable to a PC running the ServoSet application.
     

     
    The Servoset application runs on windows (there is a java based version available I believe for linux users). The left hand side of the display shows which servo you are programming and where it is connected on the Servo4 board. In the centre are the sliders which you move up and down to set the on and off positions and the speed you want the servo to move at. Once happy you just write the data to the board and you can disconnect the PC.
     

     
    The servos make a noise if you push them too hard so it is easy to get a feel for where to set the end points, you shouldn't need so much torque that the servo buzzes. The servo controller switches off the power to the servo after 5 seconds so that they are completely silent once changed (unlike some of the alternatives which stall a motor and can hum gentle to themselves).
     
    If you are offended by a brief plug for the MERG please stop reading now!
     
    Just to finish, a few thoughts about cost. A quick internet trawl shows a typical Tortoise point motor at about GBP 14.50, a Cobalt point motor at GBP 17.50 and a typical Servo at under GBP 3 and the MERG's Servo4 board at GBP 5.50. So, four points driven by Tortoises would cost GBP 58.00 while four driven by servos comes out at GBP 17.50. I think the difference pays for the MERG membership fee several times over.
     
    David
  22. Fen End Pit
    I realized that the spring on the lever was effectively duplicating the one in the micro-switch so in the best traditions of trying to keep things simple I tried to build a version which doesn't bother using it. The revised lever arrangement is a bit simpler but it takes a little bit of adjustment to:-

    get the springing in the lever right,
    the micro-switch to change correctly as the catch handle is pulled and also
    the screw which fastens the attachment to the lever not to foul the micro-switch on the lever.


     
     
    The resulting modules fasten on the levers quite well. (though I realized after I took this picture I'd got the one on the end with the mounting bracket upside down.
     

     
    Then I thought I'd turn to the locking bar. This is very much option 1 so I'm expecting to have a load of different arrangements before I settle on the best way of working. This version using the push rods on the frame which pass through a 'key hole' shaped hole. A piece of brass tube will only go through the large part of the 'key hole'. I used a piece of square brass tube as the basis of the locking bar as it is stronger than a sheet material. I drilled 2 1.2mm holes 5mm apart for each lever and then opened both the holes out to 4mm on one side and one of them to 4mm on the other. The I joined the holes up with a piecing saw and a dremel to make the shape required.
     
    The photos below show the operating sequence.
     
    Initially all the levers are locked as the piece of tube around the push rod is trapped behind the lock in the small part of the 'key hole' shape.
     

     
    The lock moves the the left aligning the large part of the 'key hole' with the push rod.
     

     
    A lever (in this case lever 2nd from the left is reversed, pushing the piece of tube through the larger part of the 'key hole'.
     

     
    Finally the locking bar slides back to the right locking the push rods again, in this case with the piece of tube on lever 2 on the other side of the lock.
     

     
    It works in theory, I just need to try and connect a servo to the locking bar now!
     
    I think I'd like to make the locking 'spring loaded' so the servo pushes the locking off, but a spring pushes it back. That way if you release the catch handle, but the lock isn't quite aligned exactly the servo can just go back to the locked position but a spring actually does the work.
     
    Any one got any better ideas?
     
     
    David
  23. Fen End Pit
    Progress on the Simplex continues, the parts supplied with the kit fitted together superbly and getting the bearings and axles, motor, wheels, gears and delrin chain was very straight-forward.
     

    The supplied sprung pick-ups have been inserted into the frames with the wires just lose pending wiring to the DCC chip.
     
    The quality of the molded parts is excellent and the instructions have the look of a Hayne's manual. When the parts list includes 'Spark plugs' and 'Magneto' you know you are onto a good thing! (must remember to make some empty 'Champion Spark Plug' boxes to have discarded in the shed!)
     

     

    Thanks to Nigel Lawton I now have a 12v micro-motor which can drive the fan, this required a little bit of material removing from the inside of the engine block casting. The kit includes a metal pulley wheel for the radiator belt but this comes as a single turning complete with axle. Rather than try and remove the axle and drill a hole for the motor shaft, which is what Roy Link did in his model in The Review 102, I opted to order an adapter shaft from Nigel to take the 1mm up to 1.5mm and then get a replacement brass pulley wheel.
     

     
    In order to support the fan drive motor I needed a little cradle which could go on the main drive motor. This means that the fan motor can be securely held to the chassis and just project through the main 'footplate' casting. The cradle was modeled up and printed out of the FDM printer. 5 minutes of drawing and 12 minutes of printing!
     

     
    I visited the St. Neot's show yesterday, very good once we actually got in but I was having a sense of humour bypass while waiting in the over-flow car park for 40 minutes waiting for a bus. The organisers had been let down by their transport company and were having to scrabble to find alternatives. Fortunately by the time we wanted to get back the lack of buses had been sorted. While at the show I spoke to Digitrains and purchased an MX648R sound decoder with a custom 'Simplex' sound installed. I've also got a bunch of 'stay-alive' capacitors and a Zimo speaker to install. The speaker should easily fit in the hollow bottom of the fuel tank!
     
    Quite a lot of gubbins to install, but it looks like it should all go in. I wasn't so sure that I'd manage to get my usual Lenz Gold + Power-1 + Dietz SUSI sound chip in and finding that there was a custom Simplex sound project available was the clincher. I'm not too sure about connecting the fan motor to the DCC chip, my friends in the MERG seem to suggest I can just connect it directly to an accessory output and control the speed using 'dimming' functions on the chip but any other experience would be very useful to know about.
     
    David
  24. Fen End Pit
    Over the last couple of weeks I got to pretty much finish off the LBT, the most noticeable change being to clean off the etched builders plates. I then went on to make some changes to the drawings based on what I'd learnt putting it together and then laser cut the body work for the LAT. There are a few subtle changes to the frames (the LBT has a hole near the front which the LAT doesn't have) and the bonnet (which has a different shaped grill for the radiator and the sandbox fillers). The LAT had a different engine to the LBT so I had to draw, sorry 'model' (got to get used to this 3D terminology) a different shape for the engine block. It is quite distinctive with a fly-wheel with an angle edge to the fly-wheel. My etching had parts for both the LAT and LBT on it so that makes progress easier.
     

     
     
    Progress was slightly delayed by a wonderful week in the lake district. Of course this had to include the usual trip to Thelkeld and a ride up into the quarry behind Sir Tom while admiring the finest collection of drag lines and other plant in the country. A particular pleasure was being able to record a 10-RB working, I'll try to edit the sound and then use it on the MP3 player that I sometimes put under the layout.
     

     
    The Makerbot had some pretty bright green ABS in it but it will be fine once painted. I'm hoping to get the LAT finished for a outing of Fen End Pit on 30th May.
     

     
    Hope you like them.
     
    David
  25. Fen End Pit
    Taking on-board the advice from KH1 and Middlepeak I had some further goes at the brickwork on the building. Running in some very dilute acrylic white into the mortar joints worked well and then I tried just lifting the colour of the bricks using some Derwent graphic pencils. Using a couple of different colours on the brick red gets quite a nice subtle variation in my view and I hope I've toned down the quions to slightly better grey-yellow of the Cambridge white bricks.
     

     

     
    On Friday I also made a trip to the cutter and had a first go at the windows. I cut these in 1.5mm MDF and you can draw the glazing bars at about .7mm and still cut them. Careful sanding takes the depth down to about .75mm before painting and sticking onto some clear plastic.The result can been seen in this rather cruel enlargement (the actual height of this section is 50mm), at any kind of distance it looks pretty good.
     

     
    Justin1985 asked about the drawing shown on the previous post. This was the drawings of Takeley, available for purchase and download from the GERS site.
     
    thanks
    David
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