Building The Canyon Diablo Bridge

[TrainCat2]

I thought (first mistake) that I would catalog what it takes to assemble this bridge since I have received several emails on how difficult it will be to build. I have already built one Main Truss and started on the second one on Sunday. I will add pics as I go along and try to describe what I am doing the best I can.

The first thing that all of you who know my models will see is that I will use solder instead of CA Glue for the main structure. The reason . . . the solder will help in smoothing all of the main structure pieces. There is another layer of detail that overlays the main structure. These Detail Overlays will be CA'ed to the soldered structure. If you guys want a primer on bridge structures as I am going along, sound off and I will include it.

It's the Wife's XX birthday today so I don't know if I will get the first batch of pics loaded tonight. I'll see how late Jamie stays up.

[GaryHinshaw]

Looking forward to it Bob.  And congrats on your wife's 20th birthday - a real milestone. 

[TrainCat2]

OK, here is the build. One of the most important things in a kit this size and all of the small pieces is to resist the temptation of removing all of the parts from the sheet. The sheet has the part designations etched into it next to the part. To see what I mean, here are the 4 sheets required for the bridge.
Sheet A  18in x 30in Brass  2ea. Required

Sheet B  18in x 30in Brass  1ea. Required

Sheet C  12in x 24in Stainless  1/3ea. Required

Sheet D  18in x 24in Brass  1/2ea. Required

[Philip H]

Holy Pigs in a Blanket Bob!  That's stunning just as art. 

[TrainCat2]

So first I removed the Main Truss Sides from Sheet A. To conserve space, I put all of the gussets into the free area between trusses. I removed the parts setting them aside and cleaned up all of the small ties from the Truss Sides.


The bridge span is too long to fit on one sheet, so the Truss Side is split near the middle. There are alignment fingers on each of the trusses. In the photo, you can see the tie remnants on the fingers. If all of the extra metal is not removed, the two Truss Sides will not properly align.

I used a 24in steel rule and a couple of brass weights to hold the alignment while soldering the pieces together.

[TrainCat2]

The components of any truss bridge are pretty much the same, just in different configuration. The CDB Truss Sides have the straight Upper Chord, the Cantilevered Lower Chord, the vertical pieces are referred to as Posts and lastly the Diagonals. Although this graphic is for the Topock bridge, it does give a reference when I talk about components during assembly.


The joined Truss Sides are very flimsy at this point. To begin the build-up, I will attach the top sheet (or Cap Strip) of Top Chord to Side. The different Cap Strips are identified as

• Top Chord Upper Cap, or TCUC
• Top Chord Lower Cap, or TCLC
• Bottom Chord Upper Cap, or BCUC
• Bottom Chord Lower Cap, or BCLC

[TrainCat2]

There are two pieces of the Upper Cap for the Top Chord. Tabs on the Cap will correspond to the slots in the Truss Side. I used a couple of pieces of tape to help hold the Upper Cap in alignment and soldered every second or third tab. Tix Flux is my go to flux here for great clean solder joints.

You know, table edges are GREATLY underrated. They actually make soldering corners easy. Just bring the Truss Side up to the edge and the tape will help as extra hands. Start somewhere in the middle of the Cap and solder a tab/slot. Don’t worry about excess solder, you’ll need it later when you finish the edge seams. Skip a couple of tabs, align the tab/slot getting the best fit and tack solder. I like to alternate sides, go left from the center tack, then go right. That way, there is no heat build-up to warp the thin sheets.


When the first Upper Cap is tacked on, do the same for the other Upper Cap section.

[TrainCat2]

Believe it or not, making sure the Upper Cap is perpendicular to the Truss Side is probably the most critical step in this section of the build. I used a Zona square at each tab/slot tack that I did along the entire length of the Truss Side. Use gentle pressure either way on the Upper Cap until perpendicular.


Once the entire length is complete, put the assembly back over the edge and finish tacking all of the remaining tab/slots.

[peteski]

I just finished reading this thread and my jaw is still on the floor, but I'm glad that my typing fingers are still functioning.    This must be the largest N scale photoetched brass structure (and the largest frets of photoetched parts) I have ever seen!  It is absolutely awesome, but I don't even want to think of the cost.

[TrainCat2]

The opposite Truss Side is secured to the Upper Cap. I used a file to hold up the Truss Side being attached. If I did not do this, the new side would not be perpendicular to the Cap like the other Side. Start in the middle as I did and tack solder a tab/slot. Skip a couple of tabs, align the tab/slot getting the best fit and tack solder. I like to alternate sides like before going left from the center tack, then going right. That way, there is no heat build-up to warp the thin sheets.


You need to check each tack solder on the new Side before proceeding. If there were any gaps at the tab/slot, use something to press the pieces together as you apply the soldering iron. I then tacked the remaining tab/slots for the Upper Cap.

The opposite of the Top Chord Upper Cap is the Bottom Chord Lower Cap. You may notice in the pics that the first Cap soldered did not have any holes in it, but the Bottom Chord Lower Cap does. This is for weight savings, drainage and inspection. The Top Chord Upper Cap did not have them because the railway ties lie directly on the tops of the Truss Sides. The Upper Cap of the Bottom Chord will not have the holes either since it is used as an inspection walkway. As previously done, I started in the center section of the bridge with BCLC6. The different angles in the bottom cantilevered Chord require 5 different sections per end and the center section. The tabs on the Cap where fitted into the slots and tacked at three locations. I moved to the next Cap section which was BCLC5 and did the same. Since I was just tacking the Caps on, I did not worry about the assembly lying flat until the next step.

Here I turned the Side over and used my brass weights to hold the Side flat onto the bench. This made it easy to do the final fit of the two tacked Cap Strips real easy. I did a three location tack first followed by tacking the remaining tab/slot. Turn the Side back over and tack everything else.



It took me longer to photograph, crop the images and type this up than it did to do the soldering up to this point. More building tonight I hope.

[James Costello]

Looking great Bob - I am already resisting the urge to have a go at this kit, can't imagine how strong that feeling will be at the end! 

[VonRyan]

Bob, I think you and I need to work out a deal on an N scale model of the Kinzua Viaduct.
It's been a dream of mine that keeps festering in the back of my mind...


-Cody F.

[TrainCat2]

Bob, I think you and I need to work out a deal on an N scale model of the Kinzua Viaduct.
It's been a dream of mine that keeps festering in the back of my mind...

Nope, Nope, Nope! Ain't going to do it. No siree.

I may be teched . . . . I am not Masochistic.

Ok . . .  well maybe I am, but not that much!

[TrainCat2]

This bridge is so big that it requires help in it’s construction. So I would like to introduce two invaluable helpers; Thing1 and Thing2. They go where I want them and stay put until needed elsewhere. Handy Things to have around.


OK, So I continued installing the Lower Cap Strips on the Bottom Chord. The two Lower Caps (BCLC3 and BCLC4) that terminate at the Bridge Shoe pivot point have a built-in gusset for Lower Laterals. The Lower Laterals are a lattice webbed type of X-Bracing that keep the two Truss Frame from skewing into a parallelogram. . Once these are installed, they now dictate the inner of the Truss Side. Also, care must be taken when flipping the Truss Side over since the Gussets will not allow the Truss Side to lie flat. And they DO bend easily if pressured! Like everything done up to this point, each Cap Strip section is tacked in three locations, the Truss Side is flipped over and the Cap sections are secured before flipping back over and finishing tacking all tab/slots. Here are two pics of the Lower Caps tacked in place on one end of the Truss Side.

[TrainCat2]

With the Truss Side upside down, The Lower Cap Strip for the Top Chord is to be installed. Fish the Cap Strip (TCLC1 or TCLC2) through an end. TCLC1 or TCLC2 can go on either end, but the etched part ID MUST go towards the end of the Truss. There is a small notch on the end slot at the first post (P1). The Cap Strip must go in this notch for all of the other tabs to align with their slots. If the Cap is not fitting correctly, check the slot at P1. By now you know the drill on tacking some tab/slots on one side, then the other side and finally all of the remaining tab/slots for the Cap Strip. One word here though, There are no tab/slots at the junction of a Post. You need to have the Cap at the edge of the metal and tack it differently.