Building The Canyon Diablo Bridge

[Chris333]

I think you forgot a rivet right... there 

[TrainCat2]

I think you forgot a rivet right... there 

Oh Sh-t!! . . . Where! . . . Where!  . . . Oh, not another sheet revision !!!!   

[TrainCat2]

Building the Floor Beams

Before actually building the Floorbeams, a simple jig must be built to allow the builder to solder the tabs for the Upper Longitudinal. The Upper Longitudinal will consist of T-Beams soldered between the tabs on the Floorbeams in an X pattern with the two flat surfaces soldered at the crossing point. This of course dictates that one T-Beam is soldered to the top of the tab and the other to the bottom of the opposite tab.

I used 1/4 lite ply that had been laser cut for another project, but the sheet’s straight edge from the manufacturer works perfectly too. I cut some of the brass from the bridge kit sheet that was close to 1/4 and measured (approx 1.645in) and cut the piece that would go between the tabs. This was glued to the lite ply edge. I then used the tabs themselves for the placement of another strip that would go on the opposite side of the tab. This was glued to the ply.


I glued the lite ply together with the .010 brass sandwiched between creating a perfect  jig to hold the tabs vertical in all directions and keeping my hands from being burned.


There are notches in tabs that slip into notches on the sides of the Floorbeam. Place tabs in the jig and solder. Using a file, clean-up any solder that would interfere with the Overlay in a few steps.

[TrainCat2]

There are 17 of the Floorbeam FB2 that will go in all Posts except P1 where FB1 will go. After the tabs have been soldered to the web of FB2, get the Upper and Lower Capstrips that will be soldered next. The Upper Capstrip has six slots while the Lower Capstrip has five slots and wings that will be folded downward into the bend lines to create the attachments of the Post X-Bracing. It is important that the bend line is in the correct orientation (facing away from the Floorbeam). Solder the Capstrips in place and clean-up excess solder.


At this juncture, it is a VERY good practice to clean the Floorbeam assembly with lacquer thinner. I keep a wide mouth glass jar on the work bench where I can immerse the Floorbeam into and use a cheap brush to clean the assembly.


The next addition to the Floorbeam assembly is the Detail Overlays. Floorbeam FB2 will have two Overlays while FB1 will only have one on the interior side. REMOVAL OF ALL TIE REMNANTS IS CRITICAL FOR THE OVERLAY TO FIT PROPERLY. Test fit before adhering the Overlay to the web. I place thick CA on the back side of the Overlay using a toothpick to properly coat the surface and removal excess glue. Place the Overlay onto the web and press the Overlay down for a good fit. Once dry, lift the other side of the overlay and repeat the adhesion process. There is a Detail Overlay that is attached to the Lower Capstrip to give some extra detail when viewing from below.

[TrainCat2]

The FB1 Floorbeam is very similar except the tabs are basically one sided for the interior side and there is a second set of tabs for the Lower Longitudinals. The Longitudinal tabs have a bend line that must face the bottom of the Floorbeam. Also, the Lower Capstrip has bend lines that must face upward. When assembled, these tabs will be bent to match the angle of the Bottom Chord.


The assembled FB1

[TrainCat2]

Building the Lower Sway Braces and Longitudinals

There are in two basic configurations; 1) Single Sway Brace where the chord is straight and 2) Multi Piece Sway Brace where there are two Sway Braces in the exact angle as the Chord Knee. The latter allows the Longitudinals to be in parallel to the Bottom Chord.

I first built all of the alternating Cross Braces that create the Lattice Web of the Sway Brace by taking two identical multi layered Sides, flip one over so the detail is opposite on the other side. Using a sparing amount of TIX flux on the top and bottom tabs, place a minute drop of solder to hold the two halves together. The finished Lattice Web now shows multi-layered detail on both sides.


Here I am building a Knee Sway Brace. On any bridge, the Lower Sway Brace must always be perpendicular to the Chord, so two Sway Braces will be needed for each angle of the Knee. That means that the two Lattice Webs will be next to each other at the bottom of the Chord and father apart at the top of the Chord. Each pair of Lower Sway Brace Caps have the number of the associated Post etched into one of the tabs. A number 4 Sway Brace Cap will be at the junction of the Bottom Chord and Post P4.

The easiest way to build these are to place the Sway Brace Cap that has it’s slots father apart down on the building surface with the half-etched bend line facing upward. Insert a pre-soldered Lattice Web into one set of slots. Solder the Web to the Cap ensuring the Cap is perpendicular to the Cap. I do this by looking at the two pieces from the end where I can see if they are perpendicular and then touching a small drop of solder on the end tab/slot to hold it in place. Do the same thing for the other end and repeat for the second Lattice Web. Fill-in all other tabs/slots with solder.
 

Carefully bend the Bottom Chord Cap, into the bend line, to the angle of the Chord Knee associated the Post etched into the tab of the Sway Brace Cap. Refer to the TrainCat Web Site for tutorials on how to bend brass. Pinch the two Lattice Webs together forming a V. Place the assembly on the building surface with the Top Cap down. Fit the slots in Bottom Cap onto the tabs on the Lattice Web. The half-etched bend line should face upward where the tabs (when viewed from the side) are parallel.


Tack the two end tab/slot pairs first and then the remaining tab slots. Using a jewelers file, remove the excess solder from the top and bottom Caps of the Sway Brace. I found out (after I made these) that you really should clean these parts with lacquer thinner right after soldering otherwise oxidation will begin. This pic is only one day after soldering and oxidation is already beginning. Like done with the Floorbeams, place them in a jar of lacquer thinner for a one minute soak followed by a brushing.

[TrainCat2]

In building the Longitudinals, the process is basically the same as the Sway Braces. The lattice work is comprised of two half-etched pieces placed back-to-back with Capstrips. There are some differences though. Notice there is a slot half way through the Longitudinal at the center. On one side, the Capstrip is the full length of the Longitudinal. The other Capstrip is in two halfs that ARE HANDED and can only be assembled one way. Each Longitudinal set has a different length than other sets. For that reason, the sets are numbered 1 being install between P1 and P2 through 9 which will be installed between P9 and P10.


The Longitudinals are assembled with the same process as the Lower Sway Braces ensuring the half length Capstrips are installed correctly. If the half length Capstrips are reversed, they will cover the center slot and not allow the installation of the other Capstrip.


Once both Longitudinals are complete, I have placed them together like they would be installed between the Lower Sway Braces. This pic really shows how the different levels of etching have faithfully duplicated the actual bridge parts.

[amato1969]

Wow, just freakin wow.  Amazing job so far!

  Frank

[stevef45]

Has there been any updates or further construction on this?  Such an amazing piece of work so far.  If I had the patience and skill i'de love to build something like this in HO.

[TrainCat2]

Assembly of the Canyon Diablo Bridge

So, it's been awhile and I have thought about the Canyon Diablo Bridge MANY MANY times while dealing with other things. Last night, the pieces were unboxed and the sheets layed out to continue the project. There may never be another model of the CDB since the etcher I was using will not etch the 30in long sheets any more. So if I have an error that needs to be corrected, there will be some issues going forward. I am not deterred though.

I had left off with the main trusses being completed, but I could not find any pics so here are a couple showing the detail with all of the overlays added.





Then the stainless steel truss railings were added. This is the thinnest I had ever etched SS before.

[TrainCat2]

It doesn't look like it will work, but using 2in tape on the bottom of the trusses kept the them vertical enough for me to start adding in the lower sway braces and some floor beams.





I will have to work from one end to the other as once I put a sway bar and floor beam in place, I found that I could not get the cross bracing in place. Nothing is soldered yet as why the clamps are needed.

[ednadolski]

Much more than a model -- that is a major work of art!! 

(my socks must be somewhere in Nebraska by now!)

Ed

EDIT - Can somebody please go get a 'Best Of" tag for this thread?

[ednadolski]

There may never be another model of the CDB since the etcher I was using will not etch the 30in long sheets any more.

Have you checked with http://ppdltd.com/?   IIRC they used to do the longer sheet sizes, tho IDK if that has changed lately.

Then the stainless steel truss railings were added. This is the thinnest I had ever etched SS before.

How thin, may I ask?   Any special considerations?

TIA,
Ed

[TrainCat2]

PPD does have capabilities to etch sheets as long as 890mm (35in), but the max height is 590mm and my artwork is 24in (605mm). If someone actually wanted this bridge and they were willing to pay handsomely for it, I would make all new layouts. I optimized the sheet using the 30in length, but I could do it in 24in with new artwork and increased cost for new photo tools. I'll cross the bridge when I have to (pun intended).

For the SS, I did them using .004 SS and the railings are only .006 thick. PPD does not go that small. They have strict rules that my etcher pushed the boundries for me.

[peteski]

Few years back I looked for US-based companies doing photetching, and there are many out there (I did a Google search for "chemical milling companies").  Some likely do not accept small jobs, or their prices are high, but there might be local companies which would have the capacity for the size needed, and for acceptable cost.