Ben has suggested on another post that he would like to build some 1/8 scale signals for Shildon, but I think has reconsidered and agrees that to proper scale for 5" gauge makes more sense.
Rather than work in isolation, is anyone out there interested in helping to form a little group to build a batch of signals, either to use at Shildon or for their own personal use? It should be much easier if we join together.
The other thing we'll need is for someone to design a signalling scheme for Shildon, over to you Jonny!
THE LIST
It occurs to me that a bit more organising and tabulating of this project may be useful. I've an idea in my head of what needs doing, and how to do it, but it's not down on paper for us all to pick over, so hopefully the following will make things clearer for us all, and everyone can comment and pull it to pieces. When there are additions or alterations needed, I can edit it as required, so it can be kept up to date.
Painting. Later signals seem to have had all the components galvanised, but the traditional colours were black and white. Posts were black up to 3 feet above rail level (101mm above top of our base), remainder white. Fittings were black. Small fittings like U bolts, shackles, bolts etc were galvanised. Ladders and safety loops usually matched the posts. Spectacle plates were black, though the drawing for the fabricated one stipulates 'micacious iron oxide silver grey paint'. The diamond sign, when fitted, was of course white, but the back, and the edges, were matt black.
However, there were lots of exceptions. Where the balance lever was higher, the black often extended to include it. Ladders were sometimes all white, or all black. After repainting, U bolts would be covered in black or white paint, and I suspect painters would have stuck to their prenationlisation schemes on occasion.
I generally use Halfords aerosols for painting, but found the paint sometimes lifted from the arms when removing the masking tape, so I am now using paint from here, http://www.riolettcustomaerosols.co.uk. This paint dries very quickly and gives a hard finish, though I don't know if it will turn out to be tough hard or brittle hard. I am applying it onto degreased steel and grit blasted brass. They do the full range of BSS colours, we need 537 signal red, and 356 golden yellow to BSS 381c. The aerosols are not cheap, but do give a nice misty spray.
For my U bolts, I have tinned them with soft solder, then lightly abraded and sprayed with matt varnish. Not ideal, as they look a bit like they've been painted with silver paint, but at least it shouldn't chip.
Posts. 15mm & 1/2" diameter steel. We have fixed the height of the signal posts at 675mm o/a. With an overlap between the two sections of post of 25mm, the top section will need to be 341mm long, and the bottom one 359mm.
I only have one drawing of posts and it is metric, so earlier ones may have been different. Anyway, according to this one, the bottom section was reduced in diameter to fit into the top section which was hot shrunk on. The taper on the neck appears to be about 60 degrees. The joint was strengthened with a weld "with a reasonably smooth finish".
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I have plenty of 1/2" mild steel tube left if anyone can't get it locally. The 15mm stainless was from Ebay, "15mm x 1.5mm Wall T304 Stainless Steel Tube 1500mm (60") Long Repair Pipe". £17 delivered, enough for 4 signals.
Have a look under "lamp brackets" for details of the holes to be drilled for the lighting cables. The cap is simply glued on.
Base. These have been machined by Ben in 20mm grey PVC. There will be an Acrylic bottom cover and three DIN sockets for electrical connections. They will contain the electronics, servos and a lead weight for a bit of stability.
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Electronics. Over to you Jonny. There will be three signal boxes, each connected to it's signals and turnouts with 7 core cable. Each signal will have it's own Arduino, but will still be capable of being driven from 12v when at home.
Ladders. Laser cut stiles and 1/16 welding rod rungs. Also some slotted bits to hold the stiles apart for silver soldering the bits together. Eddy has assembled and primed these now. Laser cut safety loops are in stock and supplied with bends and roughly to the circular shape. Round headed bolts should be used to fix the sections of the ladder together (heads outside), hex heads for the safety loop.
Saddles and other castings. A combination of lost wax and whitemetal, as follows.
Arms and spectacle plates. Arms have been etched from 0.5mm brass. They will probably be supplied folded, but you may want to tighten them up a bit with a smooth jawed vice and steel block. Getting paint to stick to them is a bit tricky, in the end I lightly grit blasted them and used the Riolett aerosols which worked fine.
Ensure the square on the spindle fits the backblinder arm, and, checking the orientation, file a groove across a corner of the square to clear the pinch bolt. Bend the front arm, and bolt it (cranked towards the back), the spindle, and the spectacle plate together. 12BA bolts are a little bit big. I used 14BA (which all seem to have the wrong sized head), but M1.2 would have been better (available from the Model Dockyard), I think they have the same sized head, but a thicker shank of course. I used the same bolts for the arm.
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Lamp bracket. Drill and tap the two saddles and fit 12BA studs (long bolts with heads removed?) Assemble to the bracket itself. Assuming you are putting a bulb in the lamp, drill 1.6mm through the bottom saddle at the right hand end of the slot in the bracket. Turn the saddle 180 degrees. Turn the assembly over, and back drill through the bracket using the previously drilled hole in the saddle as a guide. Turn the saddle back 180 degrees. Drill the saddle using the bracket as a guide. Open up the holes if necessary to suit your cable.
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Lamp. Drill out the two centred holes in the bottom, and tap 12BA. Fit the lid, and drill through the hinge holes for 1/32 rivets. You will need to round off one edge quite a bit to clear the lid in the open position. Make up the bulbs and bulb holder as described below, then you can fit the lid, paint the lamp, and trim and fit the lens. Johnson's Klear should be good for this. You should have a spare lens, this is to allow you to experiment. If the lens is used as is, the light is a bit odd as the lens magnifies the filament, I got what I think is a better result by lightly abrading the back of the lens on fine abrasive paper. There is still a beam, but the light is more even. I have not supplied glazing for the backlight slot.
Bulbs and wiring. The bulbs supplied are 6v grain of rice which we will run at 5 volts giving a softer more parraffiny light. The first thing to do is to make the lamp holder, for which we will use the SIL header. Shorten two adjacent pins to half their length and then solder on your leads, using a minimum of solder and fine stranded wire. Bend the wires as close as possible to the pins, and fit a short piece of heat shrink sleeving to each. Cut the wires so that when they emerge from the bottom of the post, they will have tails about 6" long. Check that the sleeves will fit through the centre slot in the lamp bracket, and that the holder itself will fit into the slot in the bottom of the lamp body. Glue the holder into the lamp slightly recessed from the bottom, ensuring that there are no shorts, superglue should be fine here.
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The tails on the bulbs are extremely fine and need beefing up. To do this, trim them to about 6mm long, and solder into two holes in the header. Snap of the pair of headers, plug into the remaining strip, and holding in front of the lamp body, adjust the legs so that the filament will be in the centre of the lens. Now stiffen the whole thing by applying Araldite or Plastic Padding around the legs and the bottom of the glass. There should be enough parts for you to make a spare bulb.
Check all parts for shorts, then hook up the leads to 4.5 volts and fit the bulb to make sure all the parts work. Bolt the lamp to the bracket with a couple of round headed 12BA bolts, and feed the wires into the post. There are parts for a two pin JST plug in the kit, fit this to the wires, it should just plug onto a board in the base.
Balance lever bracket. A whitemetal casting. You will need to drill through 2.8mm for the pin. My initial thought was to thread the outer end 5BA and screw the pin in, but I tried to do it prototypically, and it worked. What's more, it was quite simple.
- Balance lever bracket reduced.jpg (68.23 KiB) Viewed 35347 times
The pin should protrude 0.8mm, and should have a flat top and bottom, presumably to take a spanner to break any rust. My dividing head is currently otherwise engaged, so no flats. I think it's worth drilling a 1/32 hole in a piece of plate, putting the split pin through it, and pulling hard to reduce the size of the eye to something more lifelike.
The balance lever pin should be about 80mm above the crank pin.
Crank base. A brass casting. The pin can be 3/32 rod, the outer end reduced to take a 10BA washer, and drilled for a 1/32 split pin. I suggest the inner end is threaded 8BA, but leave the plain portion a couple of mm longer than needed. Drill the base 3/32 for about 3mm deep, then drill and tap 8BA right through. This way, the plain portion of the pin will get some support, and it can be screwed in to just the right place without having to be too careful about lengths.
The position of the crank, height wise, would vary according to the conditions of course, but would be nominally 6 1/2" above rail level. That makes it 35mm above the base.
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Cranks and Balance Levers. These have been soldered together by Alan. You may notice the curved enlargements around the large hole in the balance lever, this is to prevent overheating and damage during the laser cutting. These curved bits should be filed off, so that the lever is straight sided. There is also extra material around the hole in the crank for the same reason, when this is filed off (if you bother) it gives a rather lopsided appearance to the area, just like the real thing oddly.
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- Shackles mounted reduced.JPG (30.14 KiB) Viewed 35409 times
I can't add more than 10 photos to this post, so have added THE LIST, part 2. It is the fourth post in this thread.
I'm certainly interested.