Work continues on the Coquihalla. Over the weekend I mostly finished up a Central Valley truss bridge kit I’d had lying around for ages. This bridge kit was very close to the prototype bridge that existed at Mile 53.4, near the Kawkawa Lake Rd bridge to the south. That steel bridge replaced what was originally a wood truss. As originally constructed, there was a wood pile trestle at each end with the truss in the middle. After the steel truss replacement was in, the pile trestle on the east side was filled in.

From the aerial photo of the site attached, it is clear the flow of the Coquihalla could expand considerably in heavy flow conditions and these flows periodically took out the pile trestle at the west end. I also note via the attached satellite photo from Google Earth how significantly different the area and river bed is. This is important when constructing historical railways: rivers do change course over time, and/or riverbank is sometimes filled in or diked for development.

I say ‘mostly finished’ with this kit because there are some differences I need to remedy. The bridge is 20 feet longer than the prototype, but rather than cut it to pieces are and manage the tricky business of piecing it back together, I decided to fudge it a bit and go with 150 ft. I am modifying the x bracing at the top to more closely resemble the original. I also acquiring some more box girders as the type of braces supplied in the kit are not correct to my prototype. I’ve never built a pile trestle but I’m looking forward to trying.

To accomplish this scene I have used the historical aerial photo and printed it on a Designjet 450c large format printer. I then overlayed it on my foam base, placed my bridge as per that photo, and am using long nails to mark off where details like bridge footing and river banks should be. Next I will carve out the banks, river, hillsides etc. Then probably to pile trestle.. then water.

Apart from the kit, I created the bridge footings from notes and measurements I took of the original onsite (pictured).  Tough to work with with all the plant life around it, but it was cool seeing that still extant footing, with the 1914 date stamp on it.  Where it is now it is almost impossible to believe that trains once passed over it.

The New Year has given me renewed vigor and desire to see at least one level of my Coquihalla model operational.

On the first level of my model, I have three bridges I must complete in order for trackage to connect.  Of the three, I have one completed (the HDPG between the second and third Quintette tunnels), I have another in kit form  to make the last Coquihalla crossing just east of CNR crossing that will be kitbashed into the right size and look, and then there’s the pin and eyebar bridge between the third and fourth Quintette tunnels.

I have to be honest.  This bridge scares the hell out of me.  Look at it.  The HDPG that took me a month to build is positively child’s play by comparison.  That one had a couple of big girders, some stringers and hangers.  Whoopdy doo.  This eyebar bridge – well, let’s just say I can see why they stopped building them this way.  Lace and lattice, eyebars and rods everywhere.  The thing looks like a spiderweb on some angles.

And then there’s the small problem of lacking plans or engineering details.  My HDPG came about thanks to an article in a modelling magazine.  The kit bridge already mostly exists.  But the pin and eyebar?  Nada.  Zilch.  No plans.  I can’t even find anyone with good field measurements.  I went out there myself, and apart from length, the rest is tricky to divine.  Tricky because the bridge is perched between two cliff sides with a river canyon underneath.  It’s impossible to measure certain parts, or even see some of them.  So there’s a lot of guesswork.  This is why I pays to take time.  As I’ve learned more about modelling, I’ve learned lots of terminology, but more important, I’ve learned what to look for.  What questions to ask.  What parts to measure.

The eyebar bridge looks intimidating, and it is, but in reality it’s pretty straightforward.  You have four trusses that run the length of the bridge and are its backbone.  Components of the trusses include posts, long horizontal stringers, and of course the eyebars.

Sandwiched in between the trusses is what appears to be plate girders.  This is what the ties (12 inches thick) appear to sit on at their ends.  From my examiniation of various photos, I cannot divine if there are any girders directly under the track.  There should be, but it’s not evident in my photos.  I suppose it’s possible these massive ties are thick enough to carry all that weight on their own.  If so, wow.  That means directly below the train is nothing but rails, the ties, some thin floorbeams and a few (torsion?) rods.  Impressive.

Now to the build.  You’d think a bridge this large would positively dominate the model.  But in scale, it’s actually only about 13 inches long and a little over an inch and a half wide.  Which makes all those rods, eyebars, channels, etc *very* finicky.  Another problem is that 6" plate steel scaled in styrene results in something that has the structural integrity of paper.  The little lips on the stringers are so small they’d almost require a magnifying glass to see.  Rivets?  Yeah, I think we’ll be skipping those.

Anyway, I’ve spent 3 years trying to figure this out.  My battle plan is to keep it as simple as possible.  First, I printed out a rectangle, in scale, representing the footprint of my bridge.  My plan is to build it upside down, starting with stringers and girders.  I’ll assemble four of those (to create four trusses).  Next, I’ll create posts.  The posts are laced on two sides, so that’s going to be tricky.  Nobody makes lace that matches the size present on the prototype.  Thus, compromise.  I found some etched brass in an X pattern rather than the > pattern used on the prototype.  I chose that because it’s a bit smaller than the > type offered was, and I can just cut the middle of the X’s to get my > pattern.  Probably what I will do is create each post in components – the sidewall, a bit of lip for the lattice to attach to.  I’ll get that done and then make a mold of it, and cast it in Alumilite over and over again.  I need 40 of them so I’m not eager to scratchbuild each one.  The bottoms will have the holes to secure the eyebars.  Between each post is four of those, plus a couple that go diagonally from bottom of one post to top of the next one down.  I’ll make a couple of each and use alumilite to replicate them also.  Once I have the trusses done, I can then install the girders, and then the floor beams and start tying it all together.  Detail bits like the rods will be done later.  Once it’s steady and strong enough, I’ll flip it over and work on the top deck.

Last night I began working on the stringers.  The stringers run the length of the bridge and each of the 10 posts per truss are bolted into them.  They have lace on the bottom and plate on top.  Immediately this presented me with a challenge – the available styrene C channel pieces were either too big, too wide, or the lips of the C shape were too long.  After finding channels that had narrow enough lips, I assembled them on some thicker-than-scale styrene strips.  I was pleased to see how strong these work, but dismayed to realize what I had was twice the size of scale.  Crap.  So I removed the c-channel and found some L shaped styrene and glued along one edge to create the c-channel shape.  Still a bit over spec, but okay.  It’s not going to be exact.  Exact would be so small and weak.  The toughest part is keeping this extremely flexible styrene straight and even.  It likes to twist and bend.  Getting one L- shaped piece in position after pulling the c-channel was about all I could do, but I think it’s looking about right.  I positioned two experimental posts I made using the brass lacing in between to check.  Those posts are more or less to scale (about 12 inches in real life), so if they fit I should be good. 

This is going to be tricky!!!

Here was my weekend project, now having some mastery of the casting process.  Build the interlocking tower at the CN/KVR diamond in Hope.

I had pictures that detailed three sides of the tower. It’s pretty basic. Rows of windows along all sides for visibility of the operator, windows on the front, and an area at the bottom where the cables came out.  This project would have faced an interminable delay if I’d had to rely on scratchbuilding every window.  I had looked around at hobby stores but could not find one close enough to a CPR No. 2.  Being able to cast meant having to get only one right, and then recast it a gazillion times (25 windows total!).

The one hitch to this was there was no indication of any doors on the sides or front of the structure.  That left the back, but no pictures exist of it.  I had to take a guess and put a door and window back there where I thought they might be.  Figured the door must be near the tracks, and on one side so that there was room once you entered for the stairs to reach the top floor.  Usually on these structures the stairs are outside, but on wider/bigger towers, apparently they could be inside.  Anyway, best guess for now until someone proves me wrong. 🙂

Roof again was a lot of guesswork – calculating the little edge at the top, the rise, and then positioning the edge in the center of a piece of styrene casting, and making diagonal cuts to its end.  That was for the front and back piece.  On the sides, I simply painted the edges of the front and back roof, and then placed a piece of casting on top of it carefully, leaving an impression of the diagonals I needed to cut.  Then I used some rubber cement and assembled.. voila!  A signal tower.  Pretty darn close, I think!

A water tower for Brookmere.

Okay – my layout is 4 levels (yes, 4), and I’ve started at the top, and Brookmere is a LONG way away from ever needing any structures, but I really, really, really wanted to do its water tower.  It’s an enclosed structure, I think about 20,000 gallons.  Now that I had learned how to cast parts, it would be easy to make some No. 2 windows, door, and roof segments.

The basic structure is easy – just clapboard styrene cut in strips.  I’ve physically been to the prototype but of course did not bring a tape measure and so was left with guesswork from photos.  But I got pretty close.  The hardest part was getting the octagon shape aligned right, and the roof.  For the octagon, I simply found one on the ‘interweb’ and printed it off, then used my photocopier to scale it properly for n-scale.  Then I just glued the walls carefully together.  The roof was trickier.  Not knowing the math well, what I ended up doing was measuring from a photograph taken directly in front of the tower.  I calculated the height of the roof, the width of each triangular roof panel at the widest end, and the radius to center of tower.  Using the height and width, I calculated the hypoteneuse using an online calculator, which gave me how long the each panel would be from the wide base to the pointy top. 

From there, I used my n-scale ruler to draw a line the width of the base of the triangle, found the center point, drew a line straight up from it, marked off the distance where the point should be (I think it was about 11 scale feet), and then used my ruler to make the sides of the triangle bisect it at the same angle.  Once I had that, I cut it out, tested it on the model, and once satisfied cut some styrene.  Just a couple pieces to make sure that they’d go together okay.  I’ll do some detailing on one piece, cast it 8 times, and voila!

I put the basic tower together for now with the few scrap pieces I had cut.  I think it looks pretty good, considering my limited skills!!

This Chistmas vacation I decided to finally get out that Alumilite casting kit my wife got me two Christmases ago.  The contents had (quite) settled in that time, but were still usable.  I’d never made molds or cast anything in my life, so naturally not knowing what I was doing, I winged it.

The rubber mold process threw me a bit.  Opening the lid and pouring a bit, I was greeted by a clear, thick fluid resembling snot.  Being ignorant of these things, I assumed that was my molding rubber, and mixed some up per the instructions.  The intent was to replicate windows and tiny detail parts that make my hands want to fall off.  Long ago I had started building Hope station, but had given up because the process of making the windows and mullions (that is what those window sticks are called) was just too laborious and finicky.  Now I could make one good window, or one good door, and cast hundreds of them.

What I did not realize of course was that the clear fluid pouring out of the RTV silicone can was one part of what was supposed to be a mixture.  At the base of the can was a white compound that was supposed to be mixed with the clear stuff but, after years of sitting, had separated.  Before I realized what was going on and found myself with a tub of hard white goo in the bottom of the can, I had run out of the clear stuff and could not remix.  Lucky for me, the clear stuff provided ideal molds anyway for my tiny detail parts.  I then mixed up the Alumilite Part A and Part B plastic mix, stirred it up nice, and did a pour.  Way too much for my tiny mold, and I ended up with a half cup of solid plastic after.  Eventually I ended up mixing it in a pen cap.  Just a few drops at a time of each part.  After a few test casts, I had enough confidence to fire off a few windows and doors and soon Hope station, the project, was recovered and on its way.

A note about casting though – it takes patience, and care.  After making a bunch of windows I decided to create a mold of a few of them so I could cast a bunch at once, which worked fine *except* I found the more alumilite I mixed up, the more difficult it was to pour and avoid bubbles, and the quicker it set.  I eventually just went back to mixing tiny amounts – 8 drops each of Part A and Part B.  Got it down to a science!

Pictured is the still unassembled Hope station, with fancy (and in need of sanding and finishing) new windows!