Ginnerbeck viaduct for Rylston Light

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Ginnerbeck viaduct for Rylston Light

Post by RylstonLight » Wed Jul 08, 2020 5:06 pm

Building Ginnerbeck viaduct for the Rylston Light Part One.

My grandfather had a bell. It sat on his mantelpiece and for twenty years he claimed he was looking for a bicycle to fit it. Madness clearly runs deep within the family. This is the story of the build of Ginnerbeck Viaduct; built before the landscape (into which it will sit) has been built.

The odd order of build is necessary because I needed the exact dimensions of the viaduct before I can finalise the footprint of the new raised beds for the RLR.

The intended plan:
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The intended elevation:
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I have an old set of JigStone moulds. Some time ago I grew tired of joining individual blocks for larger projects. I made a mould for larger sheets of stonework to ease this. I decided to use these sheets for the basis of the viaduct build.

I am not sure I would recommend this build method. I kept on having to buy more resin to cast the sheets required and it has made me realise that the profit margins for suppliers such as Pendle Valley resin kits cannot be generous.

I decided to cast the underneath of the arches after some thought for the order of the build. I knew the nominal length of the viaduct and I wanted five arches. I then had to scoot around to find a large bucket/barrel of the approximate diameter as a former. The most suitable bucket was tapered but I reckoned that as the viaduct was on arc I could absorb the taper in the difference in length of the inner and outer circumferences.

I used the mould for the wall panel draped over the bucket/barrel to cast half of the under-arch stonework. For this I used U-pol resin from Halfords. This is thick and can be spread over the curved mould without it sliding off the side onto the floor.
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When I had two of these hemi-arches I then used the barrel again the join them into a single 180deg arch. This joint was strengthened with a layer of fibre-glass resin. This process was repeated to generate the five arches required.
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Next instalment to follow . . .
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Re: Ginnerbeck viaduct for Rylston Light

Post by RylstonLight » Wed Jul 08, 2020 5:52 pm

Building Ginnerbeck viaduct for the Rylston Light Part Two.

The next task was fashioning the track bed. This is a COVID-19 project and as I am fully shielding a trip to the DIY store was out of the question. The only thing suitable in the garage was an old sheet of MDF. I marked on the track radius and cut with a jigsaw. Obviously MDF will be a liability for water ingress in future so I sealed it in resin and reinforced with the glass-fibre mat I had in stock.
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The next job was the arch side-walls. I used a standard RLR stone-wall panel to form a master for the viaduct side arches, using Fimo to fabricate additional stone courses and the key-stone arch.
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This master was surrounded by styrene sheet dams. The moulds were poured from silicon rubber using this master.
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I used P2 resin to pour each arch and the arches. After curing, they were then put in a low temperature oven for 20minutes. When they are removed they are quite pliable and are formed to the curve of the viaduct. After cooling the sides are solid again and are the correct curve.
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Letting the side-arch cast cool down in bent position.
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The arch-sides were test-fitted to the curve of the track bed panel, to ensure the curve was correct.
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Next the internal arches needed to have their side cut to match the curve of the side-wall arches. The cut-line had to be marked up by care use of try-square and rule.
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Another master and mould was produced for triangular buttresses to hide the side-wall joints.
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The length of the outer wall arc is longer than the inner of course. A second master for the convex side of the viaduct was constructed for a second mould. Another five side-arches were cast from this mould.

A number of JigStone blocks were cast from the original JigStone moulds. This were cast thinner than the usual JigStone thickness. They were then used to back the visible rear of the side arches so that both sides of the balustrade walls had moulded stone courses. A number of coping stones were cast.

So far we have cast all the pieces of a giant Airfix kit. Next we will have to assemble the kit . . .
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Re: Ginnerbeck viaduct for Rylston Light

Post by Jimmyb » Wed Jul 08, 2020 10:42 pm

Some nice work there, and some inventive methodology, I use a similar resin, but which silicon do you use for the moulds.

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Re: Ginnerbeck viaduct for Rylston Light

Post by LNR » Wed Jul 08, 2020 11:56 pm

Magnificent project Andy, of quite large proportions and handled with much inventive thought. I also share your grandfathers thoughts, having built a 5ft. long model tug after making a rusty exhaust stack, a large yacht after making an anchor (which still is not on the boat, LoL).
There is something about us modellers.
Perhaps as I've said many times "you don't have to be mad, but it helps".
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Re: Ginnerbeck viaduct for Rylston Light

Post by RylstonLight » Thu Jul 09, 2020 8:31 am

Jimmyb wrote: Wed Jul 08, 2020 10:42 pm. . . but which silicon do you use for the moulds.
I have used a variety. For small moulds I used Siligum; a two-part solid material. Advantages is that small volumes are easy, no mess and it cures for use within 20minutes. The disadvantages it is relatively costly and it is vey easy to have hidden voids that can result in either a lot of cleaning of the casting or a frankly useless mould. The cost and the fact you have to work the Siligum around the master mean large moulds are not practical.

For larger moulds I use CS25 Condensation Cure Silicon Rubber from Easy Composites (pictured in OP). This is a two-part liquid. Advantages is that it is easy and takes the imprint of the master well. Disadvantages is it is messy, hard to measure small amounts, requires building a dam around the master, and takes 24h (sometimes longer). Advantages are the final mould is very pliable compared to Siligum, larger moulds are a doddle and the detail is better. Also there is no trepidation when demoulding for the first time: you know the cast will be true to the master.

The example of the above points are the viaduct sides mould cast in CS25, and the triangular stones cast in Siligum.

I can’t comment on the resilience of the two methods as my cast runs are low. I know from more well used moulds that Siligum tends to tear with time (more pronounced with deeper moulding). I know that the standard wall-sheet mould has lasted well but that was an earlier version of the CS25 that was superseded.

Along the way I have tried a re-meltable rubber from Hobbies (messy, smelly and stiffer than CS25), and a seaweed based material which was also re-usable or would be if it was usable!

I stress that I did Iittle research and just launched in, other posters may have more informed experiences.

Andy
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Re: Ginnerbeck viaduct for Rylston Light

Post by RylstonLight » Thu Jul 09, 2020 8:37 am

LNR wrote: Wed Jul 08, 2020 11:56 pm Magnificent project Andy, of quite large proportions and handled with much inventive thought. I also share your grandfathers thoughts, having built a 5ft. long model tug after making a rusty exhaust stack, a large yacht after making an anchor (which still is not on the boat, LoL).
There is something about us modellers.
Perhaps as I've said many times "you don't have to be mad, but it helps".
Grant.
Teaser: if my other inventive thought pans out it will become apparent why the viaduct has to be made first. But it is a novel thought of such cunningness it would impress Baldrick. However it won’t be part of this post.

Andy
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Re: Ginnerbeck viaduct for Rylston Light

Post by philipy » Thu Jul 09, 2020 9:39 am

That is most impressive Andy. Both the process and the end result.
Looking forward to seeing the result of your secret reason for it. :D

As for mould material I only have very limited experience but I found that Tomps A20 RTV worked well for things like window frames. It sets in about 20mins
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Re: Ginnerbeck viaduct for Rylston Light

Post by RylstonLight » Thu Jul 09, 2020 9:46 am

Building Ginnerbeck viaduct for the Rylston Light Part Three.

At this point in the story I have a kit of cast parts. A flat curved track bed made of MDF covered with glass-fibre reinforced resin. Five U-pol cast internal arches that have had there side-edges trimmed to match the radius of the track-bed. Ten P2 cast side arches that have been pre-curved to match radius of the track-bed. Twenty-four blocks of triangular stone-blocks to cover the join between each side-arch (cast in P2). And 48 coping stones cast in P2.

First, I superglued three blocks of the triangular stones to form a strip. This was repeated so I had eight joining strips.

In true Airfix fashion the next job was to have a trial assembly without glue. The plan was to use the track-bed as a giant jig to aligned the internal-arches underneath and the side arches to, well, the side.
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The above shows the dry assembly around the curved track-bed. You can see the triangular block strips ready to cover the join between side-arch panels. A large job such as this is not for just one man so I drafted in a PW team to help. The dining-room table is effectively out of use to domestic authorities for some time!

The dry-run identified where the castings needed fettling, which was done with a large semi-round wood hasp. The castings were roughened up where joints would be made at this point. The next job was to use U-pol to fix the side-arch panels to the internal-arch panels and to each adjacent side-panel. I did this first to the inner concave side and then to the outer convex side. At this point the track bed was just used as a jig and could lift out (next photo).
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After lifting out the track-bed the previously made joints were strengthened by fillits of U-pol and any gaps filled. At this point a final trial run of my largest stock (Cheddar models coaches) was done. The triangular block strips can be seen here covering the side-arch panel joins.
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The next job was too fix the track-bed to the top of the internal-arches and to the side-arch panels using U-pol. This stage isn’t really amenable to a photo.

The idea was that the track-bed would meet the side wall flush, and then when the thin JigStone blocks were added on the inner side of the ballustrade wall they would effectively clamp the track bed to the top of the internal-arches. This would strengthen the U-pol bond between the track bed and the arches. Hopefully the close up below shows this.
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I let the lads go to work on the coping stones after the layer of JigStone blocks was added to the internal wall. BTW this last photo is a cheat as I’m pretty sure that they didn’t have HIAB cranes in 1879. (The viaduct predates the Light Railway as it was used be it’s predecessor the Rylston Tramway.)
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This was the moment of truth. In theory the whole viaduct top was supposed to be structurally sound and we should be able to lift it in one unit. If not my wife gets a plot of garden back, but the dining room becomes an indoor railway room . . .
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Re: Ginnerbeck viaduct for Rylston Light

Post by Peter Butler » Thu Jul 09, 2020 10:16 am

I have been following this build from the start but had nothing to contribute before, however, I am impressed on two counts, one being the way you have planned out the build and the materials used to achieve it and the other being the railway equipment used to supply sections to site.....
https://gardenrails.org/download/file.php?id=10778
which has a remarkable similarity to mine.....
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...both probably incorporating the same Italeri HIAB kit?
The best things in life are free.... so why am I doing this?

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Re: Ginnerbeck viaduct for Rylston Light

Post by RylstonLight » Thu Jul 09, 2020 10:25 am

Peter Butler wrote: Thu Jul 09, 2020 10:16 am ...both probably incorporating the same Italeri HIAB kit?
Yup! Yours has more interesting detail. Very nice build. But I’m intrigued by the the difference in appearance of the HIAB itself. They must be the same but yours looks a tad chunkier. Shows the effect of a different paint job. I notice you, like me, didn’t feel the need to add extra air hoses on the jib joints. I felt they were too vulnerable.

Also have you written about those very nice point rodding stools you have there in the 6 foot?

Andy
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Re: Ginnerbeck viaduct for Rylston Light

Post by Peter Butler » Thu Jul 09, 2020 10:59 am

Andy, I don't wish to stray off thread but the rodding is hand built and not commercially available.
More viaduct please... it's great!
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Re: Ginnerbeck viaduct for Rylston Light

Post by RylstonLight » Thu Jul 09, 2020 12:13 pm

Building Ginnerbeck viaduct for the Rylston Light Part Three.

The story so far: mixed two liquids together in a yogurt pot many times, pour into a piece of rubber, remove hardened blocks and stick blocks together with a smelly sticky goop on what used to be a perfectly good dining room table. Then try to lift . . .

Hurrah, I won, entropy lost.

Now I can lift it I can consider putting the top on piers. If you look back at the original planned elevation the piers are different heights as the valley side climbs to track level. The next job is to fashion something to support the shorter piers whilst I work on the viaduct. I have a huge supply of polystyrene boxes that I have been saving for several years. Why.? Well that comes back to the cunning plan that is still to be revealed. However I can borrow them for this project for now.

The idea is to simulate the ground level under each pier with polystyrene boxes and then to have extra packing above them that replace the height of every pier. Then one pier at a time the pier-packing can be knocked out and replaced by cast resin piers. The background casting process was easier for this part of the build as the pier sides can be made of flat sheets (using the standard RLR stone sheet panel).
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Before I did this I cast five plinths to sit between the arch-panel bottoms and the tops of the piers but this step somehow evaded photographic capture.

The next step was to remove the packing of one pier and replace it with a card pier to check visually for how it looked with respect to its angle of batter. Opinion was sought from the Help section of the forum; thank you for the feedback. It was useful.
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I settled on a less pronounced batter angle after the feedback and started cutting resin sheets to the same dimensions of the final card mock-up.

You might argue that it was easier to up-end the viaduct top and build the piers upside down. The advantages of building the piers correct way-up was two fold: first the very sturdy level table would enable a reliable datum level which would ensure the viaduct remained perfectly level, and second the batter on the piers would unsure they were falling in on themselves in a stable way like a pyramid whilst the U-pol was drying. This more than compensated for the time taping the polystyrene boxes together.

The first shorter pier in position with the help of Ol’ Niall Packerman, who gives a sense of scale.
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Next we see the other three piers taking shape. There is a chain visible top left. I used this as a plumb-line dropped from the centre of each plinth to mark the centre-line of each pier on the paper covering the table-top. The pier wall positions were then marked either side of the centre mark. This ensured that the piers remained vertical. What is not seen is that the top of each pier wall panel locates into a rebate cast into each plinth. This ensures stability whilst everything cures. After they cured I strengthened the piers joints with glass fibre reinforced resin to limit the tendency of the forces above splitting them like a wedge through a log.
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Next I filled the gaps remaining: some rather large. I also used U-pol to fashion a slope at the top and bottom of the triangular strips to blend them in.
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The next step was something of a failure. The nature of this build meant there were a lot of air-filled voids (in the piers and in the arch spaces immediately above the piers). Testing with track and rolling stock confirmed that these voids amplified the sounds like a guitar’s sounding box. I had the idea that using builder’s spray expanding foam would fill the voids and reduce the amplification.

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Why did it fail? Well, two reasons.

The first was that, when finished, the amount of noise abatement was negligible. The second was in the execution. The instructions clearly state to only half-fill the void. I read them, honest. I followed them, initially.

However, after a few minutes nothing seemed to be happening so I topped them up to three-quarters full. This resulted in the foam expanding first to the top of the pier - success. Then it continued to form a loaf-like mass above the opening - mild failure. I cut off the forming loaf contaminating my saw and hands (thankfully gloved) with sticky toffee-like goop. It kept coming falling down the sides of the up-ended piers in torrents of waterfalls - major failure. This episode would have made great photojournalism for this post, but with sticky ness everywhere I dare not pick up the camera. Perhaps this was an outside task; I was still in the dining room. In the eyes of the household authorities dust everywhere is one thing but goop . . .

Final part to follow if I’m still alive.
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Re: Ginnerbeck viaduct for Rylston Light

Post by LNR » Thu Jul 09, 2020 12:52 pm

This is going to look superb when finished, I hope you enjoy the final painting of it knowing your on the finishing straight.
Being ignorant of such things, does this or did this viaduct exist in real life?
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Re: Ginnerbeck viaduct for Rylston Light

Post by RylstonLight » Thu Jul 09, 2020 1:05 pm

LNR wrote: Thu Jul 09, 2020 12:52 pm Being ignorant of such things, does this or did this viaduct exist in real life?
Grant.
Does now, Grant :lol: :lol: :lol:

I admit I’m slightly flattered that you ask since it suggests I’ve captured a flavour of a real viaduct. No, it’s entirely the product of my own imagination. I looked at many images on t’internet (Yorkshire). But I know the one that set the imagination off is one above Hawes in the Dales on a route up the dale to join the Settle & Carlisle route.

A good picture is:
https://commons.wikimedia.org/wiki/File ... iaduct.jpg

Andy
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Re: Ginnerbeck viaduct for Rylston Light

Post by ge_rik » Thu Jul 09, 2020 1:22 pm

Absolutely brilliant, Andy!! I wish I'd seen this thread before making my viaduct from individual balsa blocks treated with resin wet-rot hardener.

Incidentally, how did you stop air bubbles forming in the resin? I recently saw a YouTube video where someone vibrated the table with a blade-less jigsaw to make the bubbles rise to the surface.

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Re: Ginnerbeck viaduct for Rylston Light

Post by philipy » Thu Jul 09, 2020 1:34 pm

RylstonLight wrote: Thu Jul 09, 2020 12:13 pm I read them, honest. I followed them, initially.

However, after a few minutes nothing seemed to be happening so I topped them up to three-quarters full. This resulted in the foam expanding first to the top of the pier - success. Then it continued to form a loaf-like mass above the opening - mild failure. I cut off the forming loaf contaminating my saw and hands (thankfully gloved) with sticky toffee-like goop. It kept coming falling down the sides of the up-ended piers in torrents of waterfalls - major failure.
Been there, done all of that!! :oops:

Let it fully harden and then use a screwdriver to re-scribe any filled in mortar joints. It's a pain but doable.
Philip

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Re: Ginnerbeck viaduct for Rylston Light

Post by RylstonLight » Thu Jul 09, 2020 1:40 pm

ge_rik wrote: Thu Jul 09, 2020 1:22 pm
Incidentally, how did you stop air bubbles forming in the resin? I recently saw a YouTube video where someone vibrated the table with a blade-less jigsaw to make the bubbles rise to the surface.

Rik
My technique in avoiding air bubbles is highly technical and laborious to describe so only read on if you are an expert modeller. . .

The simplest way to describe it is that I didn’t know it was a potential problem :lol: :lol: :lol:

Now I’m going back to the viaduct to look.
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Everyone knows that Rylstondale stone is very friable and prone to pitting (new addition to background folklore).

Andy
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Re: Ginnerbeck viaduct for Rylston Light

Post by Jimmyb » Thu Jul 09, 2020 1:41 pm

RylstonLight wrote: Thu Jul 09, 2020 8:31 am
Jimmyb wrote: Wed Jul 08, 2020 10:42 pm. . . but which silicon do you use for the moulds.
I have used a variety. For small moulds I used Siligum; a two-part solid material. Advantages is that small volumes are easy, no mess and it cures for use within 20minutes. The disadvantages it is relatively costly and it is vey easy to have hidden voids that can result in either a lot of cleaning of the casting or a frankly useless mould. The cost and the fact you have to work the Siligum around the master mean large moulds are not practical.

For larger moulds I use CS25 Condensation Cure Silicon Rubber from Easy Composites (pictured in OP). This is a two-part liquid. Advantages is that it is easy and takes the imprint of the master well. Disadvantages is it is messy, hard to measure small amounts, requires building a dam around the master, and takes 24h (sometimes longer). Advantages are the final mould is very pliable compared to Siligum, larger moulds are a doddle and the detail is better. Also there is no trepidation when demoulding for the first time: you know the cast will be true to the master.

The example of the above points are the viaduct sides mould cast in CS25, and the triangular stones cast in Siligum.

I can’t comment on the resilience of the two methods as my cast runs are low. I know from more well used moulds that Siligum tends to tear with time (more pronounced with deeper moulding). I know that the standard wall-sheet mould has lasted well but that was an earlier version of the CS25 that was superseded.

Along the way I have tried a re-meltable rubber from Hobbies (messy, smelly and stiffer than CS25), and a seaweed based material which was also re-usable or would be if it was usable!

I stress that I did Iittle research and just launched in, other posters may have more informed experiences.

Andy
Andy, many thanks, must admit I missed the silicon in the OP, I have used the meltable rubber, but it need a robust pattern, and didn't hold up to my plastic pattern.

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Re: Ginnerbeck viaduct for Rylston Light

Post by ge_rik » Thu Jul 09, 2020 2:00 pm

RylstonLight wrote: Thu Jul 09, 2020 1:40 pm My technique in avoiding air bubbles is highly technical and laborious to describe so only read on if you are an expert modeller. . .
The simplest way to describe it is that I didn’t know it was a potential problem :lol: :lol: :lol:
Now I’m going back to the viaduct to look.
Everyone knows that Rylstondale stone is very friable and prone to pitting (new addition to background folklore).
Andy
Those bubble pockets are hardly noticeable, no wonder you didn't see it as a problem. I think they become more prevalent when there are overhangs and/or the parts are thicker.

Rik
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Re: Ginnerbeck viaduct for Rylston Light

Post by RylstonLight » Thu Jul 09, 2020 2:30 pm

Building Ginnerbeck viaduct for the Rylston Light Final Part.

The last instalment opened with the reveal of whether the newly assembled viaduct would fall apart on its first lift. Spoiler: It didn’t.

This instalment opens with whether I survived after the debacle of the expanding foam in the dining room. Spoiler: I did :shock:

At this stage the major part of the build was complete. The final result of the expanding foam was disappointing in terms noise abatement but there was a separate benefit of doing it. The overall rigidity of the piers was improved and I would do this again.

The joins between the arch-side panels were adequately hidden by the triangular block strips, but that portion of the wall above track level was still visible as a plain butt joint with non-continuous stone courses. These needed to be blended in with forming stone courses across the joints using U-pol filler. The following (poor) photo shows the effect achieved.
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I felt that the triangular strips were a little too visually prominent. I had an old Siligum mould for a tie-rod anchor-plate that I had made for the buttresses of Lygibeck viaduct some time ago. I cast 16 anchor plates figuring that they would shrink the impact of the triangular strips.
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These were fitted to each side panel with dollops of U-pol. I filled any remaining gaps with U-pol.
Side note: over half a 3L tin of U-pol was used just in assembling and filling the viaduct.

Still another hour before the local forecast predicted rain, so into the garden for some undercoat. I’m always amazed how a unifying coat of one colour dramatically pulls a project together on a new level. It took 3 large rattle cans of plastic primer, and then a light spritz with the very little flat khaki I had in stock before the final photos for this opus.
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Now if you have followed this somewhat detailed account to the end then I thank you. Obviously I need to paint the viaduct properly and weather it, then there is the no small matter of building the miniscape into which it sits. I will post a final picture when it is weathered but there will be some delay before I can finish the paint job . . .

I have to de-goop the dining room first.

Hope you all enjoyed the ride. Andy
Andy S. at the Rylston Light Railway

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