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Today's progress was gluing down the last few sleepers, and making up a 4 degree vee for the furthest turnout on the Bury St Edmunds branch. Making such a sharp vee was ... fun ... it is incredibly fragile!

 

I've hit a bit of a query though - Bill had marked the 4 degree vee with a few different marks - a biro mark one sleeper right of the 4, and then a pencil mark another sleeper further right. But actually the angle between the diamond and the vee doesn't fit as 4 degrees on either of those sleepers - but it does if the vee moves an extra sleeper left - which is where it is posed in this picture:

 

IMG-20210323-WA0019.jpg.32792338f8a808b6b7cebaff174be6ec.jpg

 

So I have a choice of putting the vee further left than Bills mark (i.e. where it is posed in the photo), or making a less sharp vee (about 5 degree) to sit on the sleeper marked with the biro mark. I can see advantages to both - the further left position gives more space for the diamond; the further right position allows a slightly less sharp (and vulnerable) vee. I'm leaning towards the latter - is there anything else I should take into account? 

 

The "straight" stock rail for this turnout will be first to get soldered anyway - but then I need to work out where the check chairs need to go ... 

 

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I'd suggest taking a pencil rubbing of what you have, perhaps with some extra entry and exit rails temporarily soldered into place. Scan it and then overlay it with track in Templot. Then you'll get to see which arrangement works best. I did this when trying to devise a new crossover to fit some pre-existing curvy track on St Ruth. You don't necessarily need to go the whole hog - just do enough to answer your question.

 

I've tried it without too - 20 years ago I ended up with some very dodgy geometry when trying to 'ad lib' a three way in a tight using space paper templates and hand drawn track

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Firstly, I found your contribution to last Thursday's MRC "meeting" interesting.

 

Secondly, I have now had a chance to access some of my books which had been temporarily inaccessible and I couldn't find a single example of the use of single blade trap points by the GER, so if they existed they were rare. It was clear that the GER's preferred arrangement was a trap siding or head shunt complete with buffer stops, but where that wasn't possible they seem to have always used double-bladed trap points, most usually with the blade that lay inside the four-foot extended by a rail which then curved sharply across to end just short of the other running rail, rather as shown below:

GERtrappoint.jpg.5ac976412098925f16dc7515eba3d408.jpg

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This arrangement would ensure that any errant vehicles were tipped well away from the adjacent running line.  The CR did much the same, but but not with as long a rail in the 4 foot.

 

Jim

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A single blade one that resulted in a the wheels on one side going outside the gauge area away from other tracks is just as effective I think.

 

Don

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  • 1 month later...

After several months of DIY and garden projects, I've come back to this layout. Some progress over the last few evenings, although I've hit something I'm not quite happy with ...

 

Having started with the turnout vees approaching each side of the branch diamond crossing, I then filled in the little gap to make the start of the K. Then I worked back and fitted the curved switch to the first turnout (paving the way to gauge the other stock rail, which will feed in to the diamond as well).

 

However, keeping the turnout vee crossing itself straight, using the angles worked out before from Bills drawing/notes on the board, it didn't seem to align particularly smoothly with the switches. I've ended up with a bit of an S curve type situation where the blades curve normally but then slightly curve back to meet the straight crossing.

 

IMG_20210512_000933.jpg.7196432cbeb38f80f3c11a74b42ccb3b.jpg

 

Looking from directly above, this siding track seems like it necessarily has to have a slight S curve to it to fit within the available space. Doesn't it?

 

IMG_20210512_001226.jpg.d666e3cbdce7f32d299d7e10d0518496.jpg

 

Or is it a case of having to start again with the crossings on this turnout to different angles? 

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I cannot see exactly what is bothering you. However I do think that for any diamond the mostdifficult bit to adjust is the distance and alignment between the two acute crossings. This is because the rails do not align directly the alignment from one V is offset from the alignment of the other by the gauge. So I tend to lay the two acute crossing of the diamnd first then add the rest. The other thing is you say about keeping the crossing straight. I would curve one of other of the crossing legs a little if it would maake the alignment better. The angle remains the same  the rail is straght against the wingrail but can then curve slightly. I also prefer to lay the crossing then the two stock rails the switch blade comes last and takes a suitable curve between the crossing and the stock rail laying the blade first means the stock rail has to align with the blade.

I don't think you need to restart and if the is a slight waggle in the siding it willnot matter the key alignment is the main lines.

 

Don

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 What you have here is a quite common occurrence in prototype pointwork. To ensure a smooth passage through the switch on the main route the blades are offset, opposite handed, to the general curvature of the point. So although the point has curvature to the right, the deflection is to the left. This then gives this S curve. 

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I agree with @Donw and @Izzy on this.  Provided you have a smooth passage through the whole formation there should be no issue.  As they say it is more difficult to align a stock rail with a closure/switch than the other way round, especially when the stock rail then runs into another crossing.

 

Jim

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Thanks for the reassurance, chaps! The opposite handed-ness to the curve leading to an S curve seemed like a likely explanation, but worried that was wishful thinking on my part!

 

I had been aiming for completing the branch through line just to "get one route completed" - but Don's advice to work on the two acute crossings before anything else now does sound very sensible.

 

Justin

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Some progress - with aid of a bendy stick! Alignment doesn't seem 100%, but hopefully not too far off.

 

The crossover dead centre seems to have had an awful lot of rubbing out and redrawing on the plan drawn onto board - bendy stick is very helpful to decipher which is the correct line! (Although of course the button gauge is exaggerating the bulge in the middle as the ply strip is otherwise inboard of the rail - representing check gauge, I guess)

 

IMG_20210516_225938.jpg.e70c7351880ca9eb7538bd0d27e99cb1.jpg

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  • 4 weeks later...

I'm taking a bit of a break from working on the track work on Long Melford (long hours working in the garage seem less appealing now the weather is better), but I've been making a start on planning out the signal box, which will be one of only two "railway" buildings on the layout. Amongst the notes that came with the layout was a rough sketch of Long Melford Junction Signal box, with key dimensions worked out apparently from the known height of the junction signal - I spent quite a while trying to translate this into CAD, before remembering that I had picked up a copy of McLean's 'Pictorial Record of LNER Constituent Signalling' from a second hand shop ages ago (a real page turner ...). Quick check, and it reproduces what seems to be an original contractors' drawing of a GER standard signal box that is extremely similar! 

 

LongMelfordSignalWorking.jpg.8f11380917a77bd50b729ca886c7af2f.jpg

 

The only significant differences are that Long Melford was a bit shorter (fewer layers of tongue & groove above the locking room windows) and, like Sudbury Goods just down the line, it had a curious "lean to" extension on the northern side - presumably for better sighting of the junction? 

 

Sudbury Goods Junc looking South

"Sudbury Goods Junc Looking South" - Tilt Cab Man on Flickr

 

I've been working at building up blocks of the standard elements like the windows and framing, which should make it simple to build up the elevations as arrays/using blocks. I'm hoping to be able to laser cut the windows and laser engrave the flush tongue and groove/non-corner framework. Thinking of using Paxolin/SRBP - which seems to be the same thing that many continental modellers have success laser cutting as "hartpapier", and similar to the "Polybak" material Americans use as "laserboard". 

 

The thing I'm least sure about is building a structure with some actual strength to it! The signal box will be close to the front edge of the layout, between viewer and track, and I can imagine it being very vulnerable to swipes and knocks. It is primarily facing away from the viewer, but with the 'extension' having wrap around windows (including one facing the 'back'), it will be quite easy to see in. That also means the rear wall is literally the only solid element. I'm wondering about building the corner framework from 1mmx1mm brass section, and aralditing the panels between them. Does that sound sensible?

 

Also wondering about what glazing material to use. Ideally, I figure it should be something that adds a bit of strength itself - like perspex / cast acrylic. But the thinnest clear perspex I seem to be able to find is 1mm, which seems much too thick. Looking for 0.5mm clear plastic sheet, most of the stuff available seems to be PET-G (i.e. plastic bottle material) which seems to be both very flexible, and tends to have a blue-ish tint. Any suggestions would be appreciated!

 

Justin

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For glazing I've recently been using the clear material salvaged from, eg., Easter egg boxes and similar.  Not sure what it is and, although not particularly strong as a structural material it is fairly stiff.

 

As you may have seen, my signal box on Kirkallanmuir is all etched and is very strong, particularly the stairway which is in three flights.

 

Jim

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36 minutes ago, justin1985 said:

I figure it should be something that adds a bit of strength itself - like perspex / cast acrylic. But the thinnest clear perspex I seem to be able to find is 1mm

 

Here you go:

https://southernacrylics.co.uk/epages/91219bf3-65e8-4793-8013-f4c24e711941.sf/en_GB/?ObjectPath=/Shops/91219bf3-65e8-4793-8013-f4c24e711941/Products/00001

 

Ive no experience with them but they weren’t difficult to find by searching for “0.5mm acrylic”.

 

Btw, I use similar material for all of my windows and loco flush glazing.

 

HTH,

David

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38 minutes ago, Caley Jim said:

As you may have seen, my signal box on Kirkallanmuir is all etched and is very strong, particularly the stairway which is in three flights.

 

 

Yup, very impressive Jim! I've not yet tried my hand at etch design, and as I have access to lasers (little Chinese diode laser cutter at home, and access to a proper Trotec CO2 laser at a MakerSpace) I'm keen to see how much I can do with that route. Not least for the instant results for revising/tweaking. If no luck though (0.3mm window bars are definitely pushing the tolerances) then I'll bite the bullet and go etched! 

 

35 minutes ago, Kylestrome said:

 

Here you go:

https://southernacrylics.co.uk/epages/91219bf3-65e8-4793-8013-f4c24e711941.sf/en_GB/?ObjectPath=/Shops/91219bf3-65e8-4793-8013-f4c24e711941/Products/00001

 

Ive no experience with them but they weren’t difficult to find by searching for “0.5mm acrylic”.

 

Btw, I use similar material for all of my windows and loco flush glazing.

 

HTH,

David

 

Thanks David! I was mainly looking on eBay, which is usually good for these kinds of things, but I guess this might be a bit too specialised. What do you use to fit your windows using this kind of material? "Canopy glue" type stuff?

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1 hour ago, justin1985 said:

What do you use to fit your windows using this kind of material? "Canopy glue" type stuff?

 

I usually cut the panes well oversize and retain them with styrene strips so that there is no danger of them ever falling out. That method will be a bit awkward on a 2mm scale signal box, though. :scratchhead:

 

David

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Are the Ratio/Peco telegraph poles made of wangy or brittle plastic?

 

Thanks

Tim

 

(PS sorry posted in the wrong place). 

Edited by CF MRC
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1 hour ago, CF MRC said:

Are the Ratio/Peco telegraph poles made of wangy or brittle plastic?

 

Thanks

Tim

 

Not telegraph poles but I've some of their signals that are now around 25 years old and the plastic has changed with time. They are now quite brittle where they were once 'wangy'. Perhaps I should have painted the whole post and not just the bits that needed to be black!

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4 hours ago, CF MRC said:

Are the Ratio/Peco telegraph poles made of wangy or brittle plastic?

 

The only appropriate material for telegraph poles is metal, and a good first aid kit ... 

 

David

Edited by Kylestrome
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On 11/06/2021 at 14:26, CF MRC said:

Are the Ratio/Peco telegraph poles made of wangy or brittle plastic?

 

Thanks

Tim

 

(PS sorry posted in the wrong place). 


Sorry for the tardy reply but just found my pack - 211 - and they do seem to be quite bendy/pliable, a right angle curve is possible. Will take a set if held in a particular position for a while though but should stand being caught/knocked about etc.

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