Z's workbench

[Zunnan]

Hi Zunnan, may I ask where you got the oo gauge brick capping from please?

 

Sorry about the delay in replying, I found a few Wills 'Building Details Pack A' (SS46) that I'd bought a while ago and used the round capping from those sprues. I also have used the triangular capping from the same packs for parapet capping stones in the past, my 'modular' bridge shown above is one of them.

 

I use the book that 0121modeller mentions for much of my references, but the Iain Rice book you mention sounds handy in more than just for bridge construction, one to put on my radar methinks. Especially now that the club layout is approaching the point where scenery needs to be considered!

[Zunnan]

Breedon Road Bridge

 

As part of the club Bournville layout, we intend on compressing the ends of the layout to include real scenic breaks. The Southern end of the layout is the most straightforward as there are two bridges in a cutting that can be used. It is my belief that modelling both of these bridges will give the most pleasing effect. The final scenic break will be what was and still is the almost tunnel like crossing under Pershore Road in Cotteridge, prior to that is a much narrower structure linking Breedon Road with what is now Cotteridge Park. Narrow width bridges don't constitute the best scenic breaks in a shallow cutting on double track in my opinion, hence the foreshortening of the layout in this area to get the larger Pershore Road bridge in, but to keep the character of the area the second bridge is to remain and is the focus of my next bridge build.

 

Access to the bridge today is relatively simple as it provides access to Cotteridge Park from Pershore Road, which makes taking measurements of the topside very easy indeed. 100' long, 18'2" wide inside the parapet walls with 18" thick walls and coping. Thanks to the robust trackside fencing now prevalent on the network, getting measurements and even a decent view of the bridge itself is not quite so simple. The key features are that the central span is considerably larger than the outer spans with each having a 4 ring arch, it is of engineering blue brick construction with no butressing other than at the pilasters at the extreme corners, and the English bond brickwork is very undecorative with the only stone used being found in the string course, skewback and coping, and the parapet wall is flared outwards at each end of the structure.

 

A test model was built using 1.5mm Daler board, which has been followed with a couple of tweeks with a 1mm styrene sheet sub structure ready to be skinned with Slaters English Bond plasticard to give approximately 2.5-3mm thick parapet walls when skinned inside and out. An internal width of 38mm between parapets will be, once skinned, a scale 18'-18'6" wide or there abouts. The ring arches will be the biggest challenge that I can forsee, most if not all scratch built bridges like this that I have seen in N the builder seems to settle on representing the outer ring with styrene or fuse wire and leaving the rest to the imagination. This will probably be my fallback if I fail to achieve what I want, but I want something that will stand up to photography better, and the smooth sides to the real bridge will be betrayed if I do so. Whatever my solution will be to this, it will probably prove time consuming or extremely tedious...probably both!

 

The structure as it currently stands...yes, it is self supporting B)

 

 

 

[Zunnan]

Continuing from where I left off, and picking up the bridge for the first time following nearly a week away. I started by scribing the 3' long blocks which make up the string course into several lengths of 2mm by 1.5mm styrene which I then used to separate the front of the bridge into arch and parapet segments based on the road/footpath level. The parapet wall and pilasters of the real bridge have a step in them on the outside that is 5 courses in height. This works out to as near as makes no difference 4mm, so to produce the step I fixed a strip of 4mm by 0.4mm styrene directly above the string course.

 

 

From this point onwards, thanks to the relatively plain nature of the real thing it is really just a case of careful cutting with fresh scalpel blades and systematically filling in the blank white canvas.

 

 

Starting from the inside, basically because thats the easiest, the only care needed was to give the top layer enough time to bond and set on the curved parapet walls before moving on.

 

 

As the brickwork builds up the parapet and pilasters become ready to take the capstones, formed here using 3.2mm by 1.5mm styrene above the parapet and 4mm by 2mm above the pilasters. These won't be carved to shape until later in the build to prevent damage while working on the lower half.

 

 

Jumping ahead somewhat you can see here that the brick finish is applied with plenty of overlap to the base structure. With the sides in place the arches are shaped back ready to take the arch face, itself oversized to be cut back later. With the arch face located the now firmly set brick front is trimmed back and chamfered ready to take the inside face of the abutments and supports.

 

 

A whole load of trimming later and the bridge is essentially ready for considering exactly how to tackle the arch rings, then the skewbacks and then finally to painting. With the skewbacks I will probably attack these in the same way I do bedstones on girder bridges; electrical tape, filler and a fine abbrasive block (nail file). At the moment I'm thinking the rings would be best done using styrene layers, we shall see though as that will require a pretty darn precise cut above each arch in order to insert it to the right depth to be as flush with the spandrels as possible.

[Revolution Ben]

Hi Zunnan,

 

Nice work - really neat.

 

For the arches have you considered Evergreen sheet planking? I think there is one where each plank is about the same scale width as a brick, so when cut across into a strip can form a row of bricks that can then be glued across the top of the arch.

 

cheers

 

Ben A.

[Zunnan]

I had considered this approach some time ago when working on a 00 gauge arch bridge, but I encountered an issue with separating the planks in order to bend them to the shape of the arch that puts me off repeating this in N. The 'V' left at the join even when using a surgical blade is quite broad when using 1mm thick material as I am here, perfect in 00 for mortar lines, but a bit coarse for what I want to achieve. If the material was thinner I would probably do that in this instance. What I am intending on doing with this is essentially exactly the same, but rather than using cut sheet planking, doing the same using 1mm by 0.75mm strip. The 0.75mm profile being a scale 4 1/2" which is exceptionally close to the 4 1/4" width of a blue brick end, with the mortar line between rings included its just about perfect. Scribing all those mortar lines every 0.5mm in each strip for individual bricks in each ring is going to drive me insane! ....and if it doesn't work out I really will cry! (I think I'll do them in bulk to save me from myself )

[Zunnan]

It turned out to be quite a bit easier than I was working myself up to think it would be. In the end I resorted to scribing lines on 30 strips of 0.75mm by 1mm styrene strip, and then carving out the depth of the arch using dividers with a scribing tip that I last used back when I was doing a building services BTEC at the end of my apprenticeship!

 

 

Two arches down, with one scribed ready for removal of the offending brickwork.

 

 

With the brick material removed above the arches I trial fitted the styrene strip using double sided tape. After deciding that the effect was pretty much what I'm after I removed the strips from the tape and fixed them in more permanently with sparing use of mek-pak, trying not to overdo it and have the melted plastic well up between the courses as they were compressed into position with the curved end of a metal rule.

 

 

With the arches well and truly set in position I masked off pretty much all of the bridge and daubed filler which was laced with plastic adhesive (Revell professional as its nice and runny and mixes well) onto the unmasked areas which are to become the skewbacks. After leaving it to set overnight the roughly applied filler was sanded back before the masking was removed, and then I set about the cap stones with a scalpel and carefully carved them to shape...I found out very swiftly that my usual attacking with fine sandpaper and a block doesn't work with curved walls, so patience and a blade it was!

 

 

Primer hides a multitude of sins!

[0121modeller]

Neat work Zunnan, I look forward to seeing more.

[Zunnan]

I thought it would be a good idea to crack on with painting this while at the club AGM...Probably not my best idea, and not the best lighting for the task either. Lets just say the result was something I was not impressed with regardless of the positive comments! Even after some extensive poking around with varying grades of brush and several coatings of my preferred engineering brick mix thinned down to varying degrees later I think the jury is still out on whether I'm happy with the brickwork...

 

 

The stonework still needs some major work to tone it down with texturing and weathering to give the green hue that the real thing sports. Maybe I'm being over critical...at least the ring arches have come out well; there, thats one positive. Maybe it'll come together a bit more once its varnished and sitting in the cutting it was built to fit.

[Zunnan]

I know my eyesight is going, but I am still fully capable of working in N, and all being well will continue to do so for some time yet...so I'm not going to use eyesight as an excuse for this ~

 

 

So whats my excuse for jumping up a few scales? Haven't the foggiest! I just fancied a change

[Zunnan]

Nearly a year after the last one, and a whole load of strife in between (including a number of house moves), I've fallen off the wagon and have been building British N Gauge bridges again. Like the previous model of the Breedon Road/Cotteridge Park bridge, this one is for the club layout. It is a considerably simpler affair, in appearance at least, consisting of a single arch; the prototype is a short tunnel just before Kings Norton station on the Birmingham Cross City line.

 

Construction follows that of the Breedon Road bridge in that it is based on a 1mm styrene skeleton that is skinned with Slaters English bond brick plasticard. The difference here is that the bridge forms the scenic break for the layout so only one side of the bridge is required, and as it is at the end of the layout it is on a tight 24" radius curve. The real thing passes under the Pershore Road in Cotteridge at approximately 45 degrees, its wing wall on the East side follows the line of the road and the tunnel/bridge mouth is at 90 degrees to the rail with the West wing wall being a projection of the main face. So in summary - 24" radius curve overhang needs to be accomodated with fully lined innards, the wing walls are different on either side of the rail and the main parapet wall will need building at 45 degrees to the mouth along with a grass bank occupying the space above the mouth. The skeleton was actually built at the same time as the Breedon Road bridge, and then literally forgotten about as numerous things weighed me down and nobody at the club took over where I left off with it (which I'm glad of as this is proving a nice reintroduction back into my scratch building).

 

 

As per the Breedon Road bridge, the arch was scribed into the English bond brick, and the ring arch area material removed to be replaced with styrene strip with the bricks scribed into the surface. Skewbacks were done in the same manner as the bedstones for the girder bridge on page 1, using a plastic filler and electrical tape as masking.

 

 

In primer awaiting painting and the parapet wall, in situ to test clearances on the tightly curved layout end, and to check that I've matched the build I did last year on its 3 arch sibling in the foreground.

 

Next up, 12" of double sided recessed parapet wall...Oh joy!

[Southernboy]

Great to see you back Zunnan, and I'm especially glad to see you working in in N gauge again.

 

As always your bridge building is both impressive and an inspiration

 

Out of interest - is your club layout featured on RMWeb / a website somewhere?

[Zunnan]

At present I think the clubs only maintained online presence is on Facebook, but due to the limited time we have at our current premises (3 hours per week) progress is painfully slow so updates are piecemeal at best. You'll have to make do with this thread for club updates as I'm currently the only member that is carrying out scenic work away from the club that posts anything online. This is my only N Gauge outlet at present too, so everything in N here is basically club related, and I envisage that to extend into coach kit construction and a couple of loco conversions at some point in the future; we do need a Kirtley outside framed 2f or two afterall

[Zunnan]

A quick update on this one, as it is merely a simple wall...well, almost simple!

 

The Pershore Road bridge parapet is not simply a plain brick wall, and as I'm not a fan of being able to see joins in walls unless necessary I needed a way of replicating the real thing and to keep each segment as similar as possible to the next as possible while making it still practical to do.

 

 

My way around this was to build a template for the wall on the back of the Slaters 2mm English Bond sheet itself, using this the cuts would have to be made from the rear of the plastic and so lead to very few cut marks and slips on the face of the wall.

 

 

 

Doing it this way I was also able to reuse the offcuts to infill the resulting holes once the template was fixed to a sheet of styrene.

 

 

The same process was repeated to produce the other side of the parapet wall, which on this (road side) is much shallower.

 

 

With both sides fixed in place I was able to cut the top 3mm off the wall, this being provided for strength during the initial cutting stage, and the capstones were added. The capping was simply sourced from a Wills 00 gauge detailing pack, I've used it like this before, but in this instance was closer to the prototype than I could probably easily carve from styrene. The final touch was to build a simple gate post, as I had no reference to how this appeared 50 odd years ago I decided to go with what is still there now as it is still of simple timber construction.

 

Next up is painting and adding the grass verge on the railway side of the bridge that sits between the parapet wall and the bridge/tunnel mouth itself.

[Zunnan]

Perhaps more in keeping with this section of RMweb, today I have been working a little on something that is not a bridge! Shock, horror...I know!

 

As the club layout is to operate up to the closure of Bournville shed, I've been looking at named trains that ran by so that we'd have something other than little locals pottering around on the 14' frontage. A 1960 formation for the Pines very quickly gained my attention (I'm a closet S&D fan) for two reasons. Firstly, all of the Mk1 coaches are available RTR. Secondly, the catering vehicles in the formation I found aren't, and they're not Mk1 either!

 

Clue time ~

 

 

I guess the game is up with this one photo alone...showing Ultima (Etched Pixels) LMS 6 wheel bogies under construction. The only suitable sides that I've found for a P3 Restaurant Third however are printed (in LMS liveries), and I prefer the relief given by etched brass in any case. Hopefully Worsley Works will come up trumps here, I've asked Allen to produce a couple of sets of D1901/1923 sides, so with a bit of luck I'll have the sides needed to launch an attack of both Crimson/Cream and also BR Maroon liveried vehicles in the weeks ahead.

 

 

In the mean time, running chassis are under construction and almost ready for testing and weighting for running reliably in a 12 coach formation. Slightly underscale wheels are being utilised due to clearance issues in the chassis through radii down to the 18" found in the clubs fiddle yard; the centre axles will be fitted for the running trials.

[Zunnan]

The bridges as built above are now pretty much fixed into their final resting places and he scenery being built up around them; some work will be required to tame that vegetation methinks!

 

 

[SirNigelGresley4498]

Looking at the hanging basket liner it occurs to me that one of its great advantages is its depth gives real body to the embankments.

[Zunnan]

I agree entirely, its nice and easy to use and the overall effect once you've picked out all of the rope knots and bits of red string is quite pleasing. Many will argue that static grass would be better, or that basket liner is too coarse for N gauge (I'm not going to disagree on either point, in many ways both points are entirely correct), but I think that the effect the liner gives from normal viewing distance is much more important than how it looks in close up photography. Its patchy, faded and lumpy, just what I'm after! The finer stuff can and will be employed where it is needed though. 

[SydTrax]

Hi Zunnan. Just to say I've been hunting around for a while for hints on how to construct a brick girder bridge and this will help me enormously. Thanks again for posting it all!