LNWR Miniature Arm Ground Signals

[Jon Fitness]

I'd struggle with that in 7 mm scale...

 

Absolutely gorgeous though

JF

[Steve Hewitt]

 

 

Unfortunately, the black colour is making it very difficult to show the details clearly.

I'll try to arrange some daylight shots for the video.

 

Steve.

It's bright and sunny this morning, so here are a few more pics of the signal:

 

 

They're still not too clear, but a bit better I believe.

 

Here are a couple of videos which show the operation of the signal by small servo motors.

 

 

 

As a part of the Lime Street project, a new servo control system is being developed. Geoff Peters, who has created all our control systems is looking after this.

The custom built controllers will be able to control 16 servos each and will be fully integrated into the routing system.

 

As a spin off, the same fundamental system is being developed for stand alone use in a version to control two servos.

I used a pre-production version to drive this signal.

Here's a pic of the device:

 

 

I'll post some more details of this device in a separate Post in a little while.

 

Steve.

 

 

[beast66606]

Very nice Steve, I like these little signals, it's a pity they are long gone from the National network (last one was at Harrow for those interested)

[Steve Hewitt]

I've just realised that I've not shown details of the installation of the servos...

 

Knowing that things are a bit crowded underneath the baseboards on Liverpool Lime Street, I would have to be careful with the positioning of the servos.

First job was for John to crawl under the layout and mark the intended location of the signal, where the 5/16th in brass tube will pass through.

This was then photographed, and the picture emailed to me:

 

 

A chat on the phone then established the orientation.

The front of the signal will be to the top of the photo, and left is left.

This shows that I needed to install the servos so they occupied the area to the left of the signal. (The little run of cables across the front can easily be moved).

 

Next I modified the little MDF stand on which I built the signal, so the area needed for the servos was to the correct side of the installation hole.

The key to installing these signals is the hole through the baseboard which locates the signal, and the sub-baseboard on which the servos are mounted.

 

This picture shows the result.

 

 

The MDF is 15mm thick and represents John's baseboard thickness accurately.

This means if the signal is installed on this little rig, it can confidently be moved the the layout with minimum adjustment being required.

The thin plywood is the sub-board, located on the brass foundation tube of the signal.

The servos are mounted on little plywood brackets, shaped on the bandsaw, and secured by 10BA screws.

The brackets are fixed to the sub-board with superglue, reinfored with beading in the joints.

 

 

This plan view shows how compact the whole assembly is.

You can see also how the operating wires, reinforced with brass tubes up to 1/16th in dia, are fixed through the very much shortened "horns" on the servos.

The white cable is the supply to the 12v Grain of Rice lamp. The is powered from a 9v battery for testing purposes.

 

 

This final shot shows more of the detail.

You can see how short the horns have been trimmed, in order to maximise the arc of movement of the servos.

Bigger arc gives finer control and smoothness of action.

 

I'll post a few more shots when the signal is finally in place, right in front the the operators at the station turntable....

 

Steve.

 

[Steve Hewitt]

Today this little signal was installed in its correct location on Liverpool Lime Street.

It controls movement of Locos from the turntable onto Platforms 10 and 11.

 

Here it is in its permanent home:

 

 

It looks a bit lost in the vast area of the station.

 

Steve.

[Horsetan]

Funnily enough, I was at Lime Street on Monday, on the way to represent a client.......

[Steve Hewitt]

We've just had a short break in North Wales, and I managed an hour at the Conwy Valley Railway Museum.

 

They have some quite interesting displays, particularly several of Jack Nelson's perspective diaramas of LNWR subjects.

They are quite stunning, and well worth the entrance fee.

see http://www.conwyrail...eum-photos.html

 

 

 

This is also among the displays.

The single arm LNWR ground signal can be worked, by lifting the balance arm weight.

It seems complete bar the inards of the lamp.

 

Guess who didn't take his camera!

 

Steve.

[Steve Hewitt]

I've just retrieved this little signal from Lime Street Station and will have it one my demo stand at the Warley, NEC exhibition next weekend.

Please drop by for a chat and examinie it close up if you're interested.

I'll be on stand E44.

 

Steve.

[Steve Hewitt]

The original subject for this topic was the "Double" ground signal which I built for Liverpool Lime Street.

 

Things have moved on a lot since then, and one of our team- Les Green - has had quite some experience in 3D CAD design and the production of 3D Printed models and components.

 

His latest challenge is to produce the body for a LNWR Ground Signal using 3D Printing.

The moving parts: Arm, Blinder, Balance arm etc. will be etched in Nickel Silver.

 

Here is the overall design:

 

 

We're hoping that the use of Resin in the printing process will give us a durable little model, which will only be some 9mm high.

 

Steve.

[Steve Hewitt]

Realising the design in Resin and Nickel Silver:

 

First the signal body has been Printed in Resin.

Les decided to have six units produced on a single base section.

This will make handling the tiny items much easier, until the signals are assembled and need separating and mounting on their own foundations.

 

The design incorporates the holes for the two Pivots and the Optical Fibre.

First task to check that these are functional.

The pivots I use are made from Lace Pins in Nickelled Brass, the diameter being 0.45mm.

The Optical Fibre us .020in (being American) i.e. 0.5mm

 

The mechanical bits have been etched in Nickel Silver to Les's designs.

These are based on the scale drawings in Foster's book LNWR Signalling.

We are attempting wherever possible to keep to the scale dimensions.

 

The signal arm is etched in two halves - a Front and a Back.

The N/S sheet is 0.2mm thick (8thou).

The Back of the signal arm is full thickness and incorporates the hole for the pivot shaft.

The Front of the arm is half etched to represent the distinctive raised edge to the prototype signal arms.

 

The Back Blinder is a single thickness of 0.2mm N/S.

The two holes are for the Pivot Shaft (0.45mm) and the Operating Wire (0.4mm).

 

The weight Bar and extra weights are etched in 0.4mm N/S.

The extra weights will give the whole some "body" when they are soldered in place.

 

These etched items are so fine and delicate.

I just hope I can do them justice when I try to assemble them.

 

Steve.

 

 

[trustytrev]

Realising the design in Resin and Nickel Silver:

 

First the signal body has been Printed in Resin.

Printed Ground Signals1.jpg

Les decided to have six units produced on a single base section.

Printed Ground Signals2.jpg

This will make handling the tiny items much easier, until the signals are assembled and need separating and mounting on their own foundations.

 

The design incorporates the holes for the two Pivots and the Optical Fibre.

First task to check that these are functional.

RIMG0988.jpg

The pivots I use are made from Lace Pins in Nickelled Brass, the diameter being 0.45mm.

RIMG0987.jpg

The Optical Fibre us .020in (being American) i.e. 0.5mm

RIMG0989.jpg

 

The mechanical bits have been etched in Nickel Silver to Les's designs.

These are based on the scale drawings in Foster's book LNWR Signalling.

We are attempting wherever possible to keep to the scale dimensions.

 

The signal arm is etched in two halves - a Front and a Back.

RIMG0985.jpg

The N/S sheet is 0.2mm thick (8thou).

The Back of the signal arm is full thickness and incorporates the hole for the pivot shaft.

The Front of the arm is half etched to represent the distinctive raised edge to the prototype signal arms.

 

The Back Blinder is a single thickness of 0.2mm N/S.

RIMG0984.jpg

The two holes are for the Pivot Shaft (0.45mm) and the Operating Wire (0.4mm).

 

The weight Bar and extra weights are etched in 0.4mm N/S.

RIMG0986.jpg

The extra weights will give the whole some "body" when they are soldered in place.

 

These etched items are so fine and delicate.

I just hope I can do them justice when I try to assemble them.

 

Steve.

Hello Steve,

                  Those resin ground signals are exquisite.Which 3D printer was used?

trustytrev.

[Steve Hewitt]

Hello Steve,

                  Those resin ground signals are exquisite.Which 3D printer was used?

trustytrev.

Hi,

I think Les uses Shapeways for 3D printing.

Steve.

[Steve Hewitt]

A trial assembly.....

 

Starting with the etched components, first the arm:

The rear etch is fitted to the Arm Pivot - a lace pin.

Its surface is smoothed down and the front etch added.

 

The Back Blinder/Crank has its holes opened to size with a fine broach.

Pivot hole is 0.45mm and the Operating Wire hole is 0.4mm.

 

The Balance Arm has its holes prepared to the same sizes, and the weights added:

 

These three components are assembled on the Body which then allows the Operating Wire to be prepared:

It is bent up from 0.4mm Nickel Silver wire which has been blackened with Gun Blue.

A hole drilled in the printed base of the signal allows it to pass down below ground level.

 

Must not forget the Optical Fibre:

 

A view from the front shows light from my bench lamp passing through the fibre:

 

Once everything is in the correct position, the Back Blinder/Crank is soldered to the Pivot Shaft.

This keeps everything in place, and its movement can be checked.

The extended Pivot and Operating Wire still need to trimmed to length.

 

Finally I used some Translucent Glass Paint to represent the Spectacles.

This should dry in 24 hours and I can see if its thin enough to allow light from the Fibre Optic to be seen.......?

 

So far so good. It all looks very promising.

It seems to work OK when I push and pull the operating wire.

I have to decide how to transfer this to a N/S Base Plate, with foundation tube for Baseboard fitting, and also fit the Servo Motor and LED.

 

Steve.

[Steve Hewitt]

Version 2 of the design....

 

 

To make installation easier, Les and I have altered the design of the signal's base.

 

The 10mm square baseplate is provided for the signal to sit on.

Beneath this is a spigot which will fit inside a 1/4in dia brass tube.

Through this are two holes:

One to route the fibre optic (pale blue) down through the baseboard.

The second to take a 1/16in Brass tube (yellow), which will be a guide and bearing for the operating wire (brown), which in turn is sleeved with 1/32in brass tube (also brown) to give smooth operation.

 

The 1/4in brass tube will make a handle for assembling and painting the signal, and then for its location on a baseboard.

It will be long enough to ensure the servo assembly is located accurately.

 

Les has also made a couple of minor changes in the signal body:

1. the curved hole for the optical fibre has been increased to 0.6mm dia.

2. the top of the aperture in the signal's base has been relieved a little to allow the balance arm to rise a little further, giving more signal movement.

 

Steve.

 

edited for spelling (why can't you see the mistakes until after you've posted).

[Steve Hewitt]

Its all moved on bit..........

 

First the design was altered again to make the height correct

 

Then we had a trial assembly with the etched components.

 

Rear view

 

Side view. In these last two shots you can clearly see how the operating wire has to be formed from 0.4mm N/S.

 

The 5/16in dia Brass tube being used as a handle.

A shorter version will be used to mount the signal through the 35mm thick baseboard (including the batten that always gets in the way).

 

A quick blast with Halford's Gray Primer brings out all the detail in the 3D Printed Resin.

 

The arm has been painted and glazed.

 

The final assembly on test. Danger above; Clear below.

 

Under the baseboard (mock-up) we can see the servo motor and the LED with the fibre optic cable plugged in.

 

This is the set-up on  my bench for testing the signal.

It looks lost on its test frame with the GF Controllers, battery for the LED etc.

It allowed me to make this little video of it working:

 

http://youtu.be/fiQtUGuPDWg

 

Steve.

[bécasse]

Very nice, but I am not quite convinced by the two stage pull "off", shunts were usually an easy pull so the bobby would have pulled the lever over in one almost-effortless movement. Just occasionally a tight detector interface might have slowed the pull, but they were supposed to be adjusted so that that didn't happen.

 

Of signals, long pull semaphores, usually but not always distants, were the most likely to need a redoubled effort by the bobby. Some manufacturers' frames were worse than others in this respect, because of the angle the levers had to be pulled through, and sometimes the sheer amount of interlocking could make a pull sticky. LNWR frames were usually easy pulls.

[Steve Hewitt]

Thanks for your comments.

If the two stage pull off and bounce is not appropriate, we can simply switch it off as a feature on the GF Controller being used.

This is a switchable feature which can be selected individually per Servo.

 

I'll try to make another video with it switched OFF.

 

Steve.

[Steve Hewitt]

Bounce ON and OFF.....

 

Here the little video to show how easy Bounce can be selected using the GF Controls servo controller.

 

BounceOnOff

 

 

Steve.

[beast66606]

Very nice, but I am not quite convinced by the two stage pull "off", shunts were usually an easy pull so the bobby would have pulled the lever over in one almost-effortless movement. Just occasionally a tight detector interface might have slowed the pull, but they were supposed to be adjusted so that that didn't happen.

 

Of signals, long pull semaphores, usually but not always distants, were the most likely to need a redoubled effort by the bobby. Some manufacturers' frames were worse than others in this respect, because of the angle the levers had to be pulled through, and sometimes the sheer amount of interlocking could make a pull sticky. LNWR frames were usually easy pulls.

 

I've worked LNWR frames from 128 levers down to 18 and the vast majority of signals were governed by the wire run, the weight at the end was irrelevant. If the run was straight and free from nature the pull was easy, if the run was convoluted the pull was difficult.

 

Pulling signals is 80% technique and 20% strength - getting your weight moving at the right time made the pull easy, even for distants, trying to pull by brute force alone usually meant a red face as the "puller" tried to get the lever on the catch.

 

I've also pulled many other companies frames and the theory is the same, once your get how to use your weight for that type of frame, strength becomes less important.

[the penguin of doom]

I've worked LNWR frames from 128 levers down to 18 and the vast majority of signals were governed by the wire run, the weight at the end was irrelevant. If the run was straight and free from nature the pull was easy, if the run was convoluted the pull was difficult.

 

Pulling signals is 80% technique and 20% strength - getting your weight moving at the right time made the pull easy, even for distants, trying to pull by brute force alone usually meant a red face as the "puller" tried to get the lever on the catch.

 

I've also pulled many other companies frames and the theory is the same, once your get how to use your weight for that type of frame, strength becomes less important.

I only managed 125 levers, (Ok, reduced to 65 if I'm going to be honest), although we did have a couple of extra bell codes and some Brown/Red levers for some unusual shunting moves.

 

My longest pull was the up starter which had a wire adjuster for hot days to "take up the slack".

 

I'm guessing being based in the Crewe area Beast, you must have worked/be working in Stockport or somewhere large like that? Maybe Shrewsbury? I always wanted to have a visit to a box that was that busy.....

 

Great modelling here too, very inspirational Steve, thanks for sharing.

 

Cheers.

 

Sean.

[Steve Hewitt]

Look what I came across last weekend..................

 

 

 

The lamp has been "modernised":

 

Steve.