7mm Birmingham Moor Street

Discussion in 'Layout Progress' started by Focalplane, 9 April 2019.

  1. Focalplane

    Focalplane Western Thunderer

    Well, the problem has been solved. A short occurred in the first Tortoise to be wired up, that connector strip I complained about above was the problem. Everything is wired back to where it was and I have had trains crossing the scissors in all three directions.

    The irony is that the short occurred exactly as the front bogies of the Jubilee crossed the insulated gap between oval and scissor crossing, leading me to assume that it was the crossing that had the short.

    An afternoon that was heading for disaster has been rescued by a brief evening's work.

    I have just seen Martyn's post (above) - I hope that with better wiring I can avoid the extra expenditure of the frog juicers. Five Tortoises wired now (only three levers though) with plenty more to do. I am going to pre-solder up the connectors where possible and improve the insulation to avoid shorts.
    Keith Phillips, David B and 3 LINK like this.
  2. simond

    simond Western Thunderer

    Good to hear that you’ve sorted it.

    Frog juicers are an effective solution but I tend to the view that they’re a pretty massive hammer for a relatively small nut...



    (Who is just going to attach a microswitch to a Tortoise whose internal switch has died, thus leaving the frog in a Schroedinger’s cat-like state of not knowing which polarity it should be)
  3. 3 LINK

    3 LINK Western Thunderer

    But Simon, this is me you are talking about ;).

  4. simond

    simond Western Thunderer


    Have faith, you can do it!

    3 LINK likes this.
  5. Focalplane

    Focalplane Western Thunderer

    Our internet went down last night so I spent much of the morning troubleshooting and then "chatting" with Orange Telecom. An engineer needs to visit tomorrow morning and hopefully all will be back to normal. But I am tethered to my iPhone at the moment while Orange gave me 200GB additional data to "spend". This afternoon I wired up another point and have come to some conclusions:
    • The DCC Concepts levers are very good but the wiring is tortuous
    • The Tortoises can go one way or the other. Usually the direction is opposite to what I want it to be!
    • Bus bars are required to wire up the 20 plus levers to common returns. But wires can't be soldered until the polarity is tested.
    • The whole thing is going to have a Heath Robinson look about it UNDER the baseboard and BEHIND the eventual curtain.
    • And I haven't even started to think about the illuminated track diagram!
    I really can't wait to get the wiring completed but like others I find wiring tedious, boring and fraught with errors (I had a short on one of the levers which was entirely due to the small size of the connectors, one strand of wire crossed a 1 mm gap).

    Her Upstairs had a demo of the Jubilee crossing over the scissor crossing from inner circuit to outer circuit and back and was dutifully impressed!
  6. Focalplane

    Focalplane Western Thunderer

    Orange Telecom showed up this morning at 8:30 and found that the outside wire connection needed rewiring, so "not my fault" and nothing to pay. Just in time for Peaky Blinders which starts here tomorrow evening!

    To keep busy I started cleaning up my workshop, located in an annex to the garage. I am not prepared to show any photos yet, it's a mammoth job now that bench construction is over and new projects will begin soon enough. To help keep sane (!) I started to solder the connections for the DCC Concepts levers. Here is the first batch, by now I have completed them all (20+).


    My soldering technique for electrical wiring has improved no end!

    Later today I went for a walk and as usual had a think about the layout. On return I looked through my 4mm stash and found I had enough Bachmann wagon chassis to mount the traversers on them instead of the current Chinese ball bearings on brass rods. I also have some hand made OO gauge track which was destined for Shipston on Stour which can act as the actual load bearing rails while the scale rails will simply be representations of what was really there.

    I will also add a "guide rail" under each traverser to keep it from wandering (though I hope the 4mm wagon chassis will do a better job anyway). The traversers will be lighter as a result and easier to move. The undercarriage will be slightly higher than before so I plan to mount the traverser track directly on the deck with fishplates at regular intervals to help the CA glue adhesion.

    I am not sure when I will carry out all this on the layout but when I start I will be sure to document the progress.
  7. simond

    simond Western Thunderer


    You’ll not be surprised to hear that I don’t favour your traverser approach...

    I’d still recommend fitting the deck rigidly to the leadscrew carriage (ideally with three levelling screws) and keeping the scenic rails for show. The leadscrew base would need levelling screws (or shims) to ensure the tracks match at both extremes.

  8. Focalplane

    Focalplane Western Thunderer


    Give me a chance to prove you are right!

    Best, Paul
    Peter Cross likes this.
  9. simond

    simond Western Thunderer

    I’m patient....

  10. Focalplane

    Focalplane Western Thunderer

    Patience is a virtue, in this case probably essential.

    The signal box levers must take priority! So food for thought, Simon.
  11. Focalplane

    Focalplane Western Thunderer

    Today I installed pipe insulation to protect my balding bonce from further damage. And while in the process I added an incorrect "totem" to the entrance:


    Yes, its LM(R) maroon! And the sub-text hidden from view says "New Street". Who will know?
  12. Focalplane

    Focalplane Western Thunderer

    I have done some experimental work on the revised traverser design and so far the 4mm scale truck chassis(s) and 4mm scale track have provided a much better (smoother, quieter and more stable) undercarriage. With a bit more thought I am hoping that a more rigid connection between motor and traverser will eventually work out to Simon's approval.

    I am also persevering with the point motor wiring, remembering the key to correct mapping out of the wires to a double slip - opposite frogs!

    Yesterday evening I painted some of the baseboards a brown base coat to represent the "ground". In fact most of the layout is based on structures that were built on the Bordesley Viaduct so brown soil is not being represented, rather brown city dirt! Due to providing access to the various parts of the layout there are gaps that did not exist, for example between the Snow Hill main lines and the surface goods yard and these will have to have scenery. I am thinking typical post WWII bomb site weeds (Rose Bay Willow Herb was everywhere) springing up on the now neglected strips of gravelly land. If the model was of today, of course, the vegetation would be mostly Buddleia ("butterfly trees") which is slowly destroying Network Rail's blue brick walls. Other areas will be covered with cobble paving as shown in period photos when horses were the main source of haulage power in the goods station. The surface goods yard included electric motors and capstans with ?paved ground to assist the movement of wagons with cables.
    Last edited: 6 October 2019
    Deano747 and Pencarrow like this.
  13. Focalplane

    Focalplane Western Thunderer

    Some practical work on the first traverser, mark 2. And Simon, you will be pleased to know that a direct coupling to the Arduino controlled motor may well be possible.

    The new undercarriage works so much better than the the mark 1 version. Free running and hardly any slop. In fact if I add weight under the Tufnol it will probably be even more stable when moving. I have relaid the track, using CA adhesive to bond the rails directly onto the Tufnol. I have also added styrene "plates" between the rails and now primed and painted the deck satin black. I have also laid cinders on the well floor to represent whatever was there (there are no photos of the nature of this). Some photos:

    Relaying the rails (with CA glue)


    Added the styrene "plates" and cleaned the central running "live" rails:


    Added cinders where the well is visible. The 4mm scale track is quite well hidden.


    The small white square between the tracks will house the warning signal to drivers when the traverser is/is not available, a simple red/green affair.

    I plan to add weathering later, including some rust, grease, litter, etc.
  14. Focalplane

    Focalplane Western Thunderer

    A day later and some of the styrene "plates" lifted over night. I don't think Mek-Pak is suitable for gluing styrene to Tufnol. So maybe the CA adhesive will have to be employed. I have started on measuring the second traverser (between Platforms 1 and 2) and will work on this one before it is installed in the layout to design the connection (rigid) to the motor drive and test the electronics. But then we had an imposter arrive from Oswestry:


    I think the time must be around 1966 and the Ivatt 2MT has been loaned to Saltley as it began to take over Moor Street's operations. There is photographic evidence of an Ivatt shunting at the Goods Station:

    Moor Street Station: Ex-LMS 2MT 2-6-0 No 46457 is seen shunting wagons and parcel vans adjacent to Moor Streets upper goods shed in June 1966

    The Ivatt takes up most of the traverser table's length so I doubt if a Castle or even a Hall will fit easily when reversing around a rake of coaches. But the table was built to the prototype's specifications.
    Deano747, jonte, Geoff and 5 others like this.
  15. Focalplane

    Focalplane Western Thunderer

    How to fix the traverser motor to the baseboard (traverser well) and the traverser deck to the motor? Simon suggests that the fixtures need to be rigid. My current design has the added advantage of the 4mm truck chassis and tracks to act as "outriders" to help stability. So, how to build an effective assembly?

    The first photo is of the motor assembly with some added metalwork to fix it to the baseboard (traverser well):


    The steel bars are bolted to grooves in the motor track and then 6mm thread runs up to meet the base of the traverser well. How these rods will be fixed to the traverser well has yet to be decided but there should be a simple solution available at the local bricolage. The nuts will allow small adjustments to each corner of the assembly.

    The next photo shows the motor assemble positioned above the traverser well (when in fact it will be below!) in order to show where the motor carriage sits. This will be in the opening with short 6mm bolts connecting the carriage to the underside of the traverser deck:


    The various 6mm thread bolts are there for illustration purposes. The connection between motor carriage and base of traverser deck will be much less than suggested by the countersunk bolts.

    Next I put the motor assembly under the traverser well, resting on wood bocks with the carriage in the opening.


    The lateral travel required is 85mm.

    Finally, the deck will sit on the 4mm scale tracks but in this photo it is raised on the four countersunk bolts. These will be shortened so that they can be fastened to nuts fixed to the underside of the deck.

    I am putting this all down in print for the record and to compare with any suggestions to improve the design. Which will be welcome!
    Deano747, jonte, simond and 1 other person like this.
  16. Yorkshire Dave

    Yorkshire Dave Western Thunderer

    An excuse for a station pilot ;)
    Focalplane likes this.
  17. simond

    simond Western Thunderer


    I like the progress!

    You now have the table supported and guided by the OO trucks & rails, and you have to ensure that your leadscrew assembly does not “fight” the constraints that the rails & trucks provide. “Hyperstatism” should be avoided as it will probably, indeed, almost certainly, cause issues.

    First and most obvious, the leadscrew needs to be parallel with the guide rails in plan view. Options here are a) careful adjustment, b) a slot perpendicular to the direction of travel which will compensate for any non-parallelism, & c) removing the flanges from your OO trucks. I’d recommend “b”, but a bit of “a” will certainly be necessary. Certainly do not use those four countersunk bolts to attach the deck to the leadscrew carriage, unless you go with option “c” (or do away with the OO track altogether and use the leadscrew carriage as the load bearing system)

    Secondly, you need to ensure that the leadscrew carriage does not lift the traverser deck. Effectively parallel in side view too. A “pin in a hole” arrangement where the pin does not contact the end of the hole will ensure that. This is compatible with the slot in “b” above.

    Thirdly, you don’t want to rock or tip the traverser deck whilst moving it. Hence avoid applying a moment to it - the easiest way to do that is to have the slot at traverser deck height, or as close to it as practicable. This means that your “pin” is rigidly fixed to the leadscrew carriage, and can rotate in the socket in the deck - a balljoint with some sideplay effectively. I’d suggest a grommet or something similar fitted between pin & slot to prevent rattles and provide a compliant link. Perhaps one of the four CSK bolts, with a nut to fix it rigidly to the carriage?

    Finally, the endstops. The stepper motors, driver & program rely on not losing position, so if there are hard endstops on the traverser movement, they must be outside the positions where the switches are operated. If the traverser is blocked during its travel, the motor will continue to try to turn until it “thinks” it has completed the move, and then stop. I’m not sure what happens at the next reverse move, (I’d have to dig the sketch out) but I think it will try to overshoot, and be stopped by the switch. If that doesn’t reset it, turning off & on again in best Windows tradition will reset it, but in any case, you don’t want to have to do that! In any case the program is written to use the switches, so the table mustn’t physically block travel until after the switch has been triggered.

    Hoping this all makes sense,
  18. Focalplane

    Focalplane Western Thunderer


    Many thanks for your comments! I'll try to answer them para by para, my text in red:

    I started to put the second traverser together as it will be easier off the layout to test, particularly the end stop, etc.

    Many thanks, Paul
  19. simond

    simond Western Thunderer

    Sounds good, Paul. Beware of the rod-in-tube, rod-in-hole (ie a ball joint) likely to be better

    Watching with great interest & fingers firmly crossed for success!
  20. Focalplane

    Focalplane Western Thunderer