Steve Hewitt

Fitting the servos and testing........

The servos I'm using on this signal are fairly small, of conventional design, with a weight of only 3.7gms.

As usual I created a bespoke mount from plywood and beading.

This starts with a horizontal plate with a hole to match the signal's "foundation tube". In this case it is 1/2in dia.

This plate is secured to the baseboard by a couple of screws.

The three servos are mounted in a second piece of plywood, which in turn is glued to the first plate, with beading re-inforcement of the joint.

The alignment of the servos to the operating wires is determined by "rack o'th eye", with the intention of giving as straight a pull as possible.

The wooden servo mount in place on thge Transport & Test frame.

With the servos connected to GF Controllers, they are set to mid-throw by the "Safe" feature.

The servo Horns are aligned on their splines. The holes for connecting the operating wires have been opened up to 1/16th in.

The connections between operating wires and servo horns are made from 1/16in Brass tube,

This is a sliding fit over the 1/32in tube re-inforcement of the operating wires, and a good fit into each horn.

Each connection is individually formed to suit the location.

The sliding fit between the operating wire and the connection tube allows the signal arm to servo relationship is be adjusted prior to soldering the joint.

The servo is already set to Mid-Throw by the GF Controller.

The signal arm is set to the corresponding "mid throw" position.

Once the connecting tube to operating wire positionh is correct, a drop of liquid flux is placed over the small hole ready for the solder.

A little solder on a hot iron and the job's done.

Here the first two connections have been made.

Adjusting the signal movement is straight forward.

First the Stop is set.

Then the Clear.

The very small amount of movement of the servo required is seen in the following two photos:

Stop.

Clear.

By ensuring the thickness of the Transport &Test frame correponds closely with the railway's baseboard, the signal can be installed with confidence everything will be within the range of adjustment available. 

The connecting tubes are easily released from their servo horn to allow the servo assembly to be removed downwards, and the signal upwards.

On installation a short length of 1/12in tube or rod is used to align the servo mount whilst it is screwed in position.

I hope the above has been informative.

I hope to have a short video prepared soon...

Steve.

The Wibbly Wobbly bits.........

(Not too wobbley I hope)

Each of the three moving arms of this signal will be moved by a servo motor mounted underneath the baseboard.

The motion of the servo motor will be transmitted to the signal arm in three steps, with cranks between each step.

The steps are:

1. The vertical pull wire from the servo, routed up the leg of the gantry to a crank at the end of the signal platform.
2. The horizontal pull wire along the gantry to the weight bar at the base of the signal's doll.
3. The "Down Rod" push link up to the lower quadrant signal arm.

All these links are made from 0.4mm N/S wire, blackened with Gun Blue".

I actually made the connections in reverse order, starting with the left hand arm - a Centre Pivot Short Arm.

The Down Rod is connected to the arm at a very short radius to the pivot, as seen above.

From this it can be seen how small a movement of the Down Rod will be required to move the signal.

The lower end of the Down Rod is conected to the Weight Bar.

In this shot it has not yet been secured, which I do by flattening the wire as close as possible to the bar using parallel action plyers, which give a great mechanical advantage over ordinary plyers.

The next link installed was the vertical pull wire from gantry level to the servo.

I first prepared three pull wires as they are identical for each arm.

These comprise a N/S wire from the crank to below the base of the signal with the lower section from Ground Level down re-inforced with 1/32in brass tube.

The lower end of the re-inforcing tube ready for soldering to the N/S wire.

(Ensure the N/S wire has had any blackening removed where it is to be soldered.)

Two of the Pull Wires with the brass tube attached.

The upper end of the pull wire is connected to its crank on the gantry.

The 1/32in brass tube runs smoothly in its guide tube fixed into the base of the signal.

The lower end extends below the bottom of the signal and will ultimately be connected to the servo arm.

The last link to install is the horizontal connection from the Weight Bar to the Crank.

Un-prototypical kinks have to be made to ensure the wire can both Push as well as Pull.

The prototype of course is pulled in both directions, by the signaller to clear the signal and by the Weight Bar when it returns to Danger.

All three signals have been connected in this shot.

The three Pull Wires awaiting connection to their servos.

The movement of each arm depands on accurate control of all the components. Any "slop" in the linksges will jeapordise a final result.

There are a total of seven pivots between servo and arm which have to have some clearance for minimum friction.  

Control depends entirely on the servo motor as there are no mechanical stops.

In turn that servo control is given by th GF Controllers I use.

Fitting the servos will be next..........

Steve.

The paint is now dry............

Assembly of the dolls was straight forward, once I had relieved the turned base of the taller pair to facilitate installing the optical fibres.

I have been asked to show some detail of the optical fibre installation, so please bare with me if the following piccies are a bit repetitive.

Each signal lamp, five in total, requires one optical fibre to carry the light from a LED to the front of the lamp.

The fibre is 0.5mm (0.020 in.) dia. (American product from  Circuitron who also make Tortoise point motors).

It is routed through the lamp and down the structure of the signal to the LED below the baseboard.

Where necessary, the fibres are "tie-wrapped" to the structure with fine cotton. A dab of paint later will render the threads almost invisible.

When the fibres arrive below the baseboard, they are shielded with "heat shrink" tubing.

This ensures they are easy to see, and provides some physical protection.

The lower end of the fibres are terminated in a 3D printed "Plug".

The extreme end is given a dab of Yellow Glass paint to kill the intensity of the Warm White LEDs I currently use.

(The "Gaslight" LEDs I have used for years are currently unavailable. The original retailer has retired and his Helmsman products have gone to Peco, who have not yet made them available.)

The actual LED with its 1K ohm resister is mounted in the 3D printed "Socket".

Plug together.

Apply DC Volts (9-12), seen here being tested using a PP3 battery.

The result.

The Optical Fibre leaks a little light where it is bent  quite sharply to enter the rear of the lamp.

This gives an effective "Backlight".

The staging timbers have been fitted, and after a few paint "touch ups" it will be time to add the Wibbly Wobbly bits.

More soon, I hope......................

(A lockdown benefit is more "shed time")

Steve.

Another Gantry for the GWR terminus..........

A couple of months ago or more I showed the Gantry controlling the Up approach to the Edgeware Road terminus.

Its now time for the Down lines partner to be built.

This gantry is a similar design, but with a shorter span.

Only three dolls, each with one working arm. The two dolls for the main running routes also have Fixed Distants.

The main structure has 12 inch square H section main posts supporting 9 inch channel section trimmers.

The corners are strengthened with two pairs of small brackets.

The dolls are hollow 3D printed items, from Les Greens Shapeways Shop.

The bottom of each doll is turned to give a location spigot (hidden by my fingers above).

To  ensure the doll spacing is correct I prepared this simple jig.

I drilled holes to take short lengths of silver steel, the same diameter as the bottom of the dolls.

Using the table of my tiny milling machine made this a very simple task.

Each doll requires a socket into which it will eventually be glued.

These were drilled and cut from 4mm square brass bar in the lathe.

The doll sockets were soldered in place between the trimmers with everything checked for squareness and alignment.

Holes for the Handrail Stanchions were also drilled in the milling machine, using the table index to get the correct spacing.

The supports for the staging are made ffrom 1mm x 0.5mm brass strip.

The stanchions are 0.45mm dia Lace Pins.

A base plate was prepared for each leg.

Because of subterranean obstructions the servo motors to operate this signal will have to be located under the right hand leg. The access ladder is also located at this end, leaving only the optical fibres for the lights to be routed down the left hand leg.

The right hand leg is therefore finished with a 1/2in dia brass tube, which will locate the signal with the servo assembly.

The turned foundation for the left hand leg is some 8mm dia and will only require a clearance hole in the baseboard to prevent any rotation of the signal.

The guide tubes for the operating wires are fitted in the recess of the H section right hand leg.

To get the operating wires across the gantry to the dolls requires three cranks mounted on the trimmers.

A trial fit of the dolls.

The signal mounted on its Transport & Test frame has received its access ladder and handrails.

At this stage it was given a really good clean with scrapers, files, emery boards etc. and then treated to a trip in the dish washer.

With all the components mechanically cleaned they enjoyed a bath together in cellulose thinners, after a thorough drying its time for the paintshop.

More about that when the paint is dry...................

Steve.

Two months and a day since my last post..............

Having enjoyed a great holiday in Cornwall, delivering those GW signals on the way, I have been busy with four LMS/BR single post signals for a model of Kirkby Stephen.

They were built from photos supplied by the layout owner and followed my usual methods.

Here they are, ready for testing prior to delivery.

The tall lattice post is the only "work in progress" shot I remembered to take.

I did manage tiny Video clip of the testing:

More soon...

Steve.

Quiet but not idle.....

The Covid-19 restrictions have curtailed much of the teams social contact, which has been confined to the telephone and fortnightly Zoom conferences. (Posh word for gossip).

John has taken advantage of unrestrained access to his railway to tackle one of the "elephant" tasks - Ballasting and Point Rodding in the Station and Station Throat.

The ballasting extends to the buffers.

It awaits the attention of Rob with his collection of muck and grime.

The point rodding runs are carefully mapped.

The route is excavated below existing track and rodding hardware temporarily installed.

It gets quite congested nearer to the signal box!

All this temporary installation is then removed for ballasting to be completed.

It is later re-installed and weathered.

Waiting impatiently for restrictions to be lifted...

Steve.

A month has passed........

Since I reported on my signal building, but I've not been idle.

The partner to the GW Bracket signal is a Gantry with four dolls.

Another freelance design, but copying GW features from  the indispensable  "Pictorial Record...."

The overall design is dictated by the location, which is quite compact.

The main legs of the signal are "H" section girders, with the cross beams being Channel Section.

Looking ahead, the overall size of the signal can be seen here, and checked for fit on the layout.

The main "steel" work has been progressed. Here you see the "sockets" for the location of the four dolls.

The dolls are 3D printed , as are the Lamps and Lamp-n-Bearings for the two Calling-On arms.

Here they are just having trial fitting.

A good idea of how it will eventually look.

On this occasion I completed each Doll separately from the main signal, which allowed me to paint the whole Gantry with Halfords Black.

The dolls were then fairly easy to fit to the gantry, along with all the operating wires.

The completed signal.

The four right hand arms are connected to servos under the right hand leg.

Cranks transfer the pull along the gantry.

Similarly for the two arms on the left hand dolls.

As I mentioned earlier, this Gantry s a partner to the Bracket signal I completed previously.

The two signals on their "Transport & Test Frame", ready for the off.

All the arms are in their "Safe" position, with the servos locked in mid-throw.

They fit nicely in a 7 litre Really Useful Box.

Not sure what's next, but I feel a caravanning holiday coming on.............

Steve.

It's been a while.........

.............since we updated this topic.

The Lockdown has constrained our activities somewhat, and we missed the Bristol Show of course.

The big thing that we are all missing is the chance to meet and run the railway.

However, some things can still be progressed and John has been very busy on the groundworks.

He is continuing the "elephant task" of ballasting and point rodding along the platforms and in the station throat.

Where the track is plain along the platforms this is fairly straight forward.

Its the rodding which complicates things.

This takes several distinct phases to achieve the required result.

First the route of the rodding between the point and the Signal Box has to be planned and marked out on the bare baseboards.

The necessary stools are the installed:

Some of this work will never be seen once the layout is running.  WHY? you might ask.

The team motto "'Cos we can" applies.

Any track crossings are excavated and rodding installed.

This is as far as John has got at present.

The ballasting will progress once individual baseboards can be removed to the workbench to give better access.

And that rodding already installed will be removed for the ballast to be laid, painted, weathered etc. before being permanently fixed, painted and weathered.

More reports as progress is made..............

Steve.

Add the moving parts....................

The six arms each require one Operating Wire/Weight Bar/Down Rod:

To prevent buckling, the Down Rods pass through guides on the main post:

The two arms on the first doll can be reached directly by their Down Rods, so don't require cranks.

The third down rod is for the stop arm on the second doll, and it has its crank to the left of the main post:

On the right hand side of the main post are the first cranks for the remaining three arms.

They share a single axle, which means things get quite crowded.

The two cranks for the second doll are next along the bracket.

The final pair of cranks are for the two arms on the third doll:

Once all the linkages were installed it was time to add the timbers to the staging and finally the 3D printed Finials from Modelu.

With the LED connected to a 9v PP3 battery, the signal is looking fairly complete:

Next will be installing the servo motors..........

Steve.