Building The Canyon Diablo Bridge

[TrainCat2]

Also part of the Sway Brace system is the Mid Sway Brace that segregates the tall Posts into smaller sections. Like the Lower Sway Brace, the Lattice Web is made of two layered components that when flipped over and placed smooth surface to smooth surface will create a true X-Lattice Web that is sandwiched between L-Girders. The Lattice Web for the Mid Brace tabs that protrude the Caps at the ends and smaller tabs that fit within half-etched slots on the Caps. I tack soldered the protruding slots ensuring the Web was perpendicular to the Cap and then did the same to the other Cap. The trick was then to solder the Web to the Cap from the inside without a huge pile of solder covering the details. I was able to accomplish this with TIX and a small drop of solder on the iron’s tip. This is where the small tip of the Weller came in real handy. With the Cap on the building surface and the Web in the half-etched slots, I just touched both Web and Cap and pulled the iron tip to allow the solder to wick into the gap. You can hardly see the solder in the center of the Mid Brace. I am not worried about solder around the X-Bracing gussets as the X-Bracing will be soldered to the Mid Brace at that location later in the build.

[chicken45]

I will say that the level of proficiency to assemble this type of bridge is MUCH lower than the G22b. You really DO want the globs of solder (in the right places of course). There are just hundreds of tabs/slots that must be done. Simple but monotonous.

I thought about soldering the G22b, but one thing in particular terrified me: soldering large flat pieces flush on a flat surface. Namely the floor to the base, and the ribs to the car side. Do you just lay down a super thin layer?
 

[TrainCat2]

Although I have not tried it for that application, there is a product known as Tinning Paint which is super finely ground lead suspended in a liquid flux. I have used it for other applications. Just paint it on and use a heat source to bond.

I don't know if I would have soldered the .005 floor detail overlay to the sub floor on the G22b. Everything else, yes.

[Leggy]

After I've saved the Pesos for a holiday I'll be saving up for one of these, my god that is beautiful!

[Ian MacMillan]

Amazing work Bob. Any progress?

[TrainCat2]

Have the metal, cleaning off the bench this afternoon. Funny, I was just coming to this thread to get the link to send it to someone so he could follow along.

Expect the building to resume this weekend.

[TrainCat2]

Applying The Detail Overlays On The Side Truss Frame

Up to this point, I have been performing the same operations to the other half of the Side Truss Frame. After all Posts, Diagonals, Upper & Lower Chord pieces have been soldered, I solder sealed all joints and then removed all of the excess solder as described above in an earlier step. Before continuing to the next process, clean the entire Side Truss Frame with lacquer thinner and a soft expendable brush. As a added step, I used an industrial paint gun spraying lacquer thinner at a high pressure of 50lbs and high flow and sprayed the thinner into the holes in the structure to clean the inside as well. BEWARE: this process must be done outdoors with the proper safety gear.

Now that is complete, I am finally ready to begin, we will start on the interior of the Side Truss Frame. The first Detail Overlay to be applied is the Top Chord Interior Side. There are two Overlays for the side and have markings etched into them. One Overlay has a “L” and “C” etched while the other has a “C” and a “R” etched into it. Start with the left Overlay. The important registration is the slot at the center of the Top Chord Side. This is where the end with the “C” will go.


Place the Overlay detail side down and use a small piece of 100 grit garnet paper and scruff-up the shiny, non-etched side of the Overlay. ALWAYS move the sand paper AWAY from you. NEVER EVER bring the sand paper back towards you while in contact with the Overlay. IT WILL CRINKLE, BEND AND MUTILATE the Overlay. I know this from my own stupidity. Now that you now this, learn from my mistakes. Ensure all of the shiny surface has been scruffed-up.

You will want to use some masking or scotch tape to help keep the alignment. I used a piece of tape every three posts as shown.

[TrainCat2]

Prop up the Overlay towards the center as shown. The first section is going to be a small one, just enough to hold the Overlay in alignment. Apply some Zap-A-Gap CA Glue starting at the center of the Top Chord Interior Side and use a toothpick to spread the glue and cover ALL of the Top Chord Side from P10 to P9. Use TP to absorb any excess glue. Remove the prop to allow the Overlay to come into contact with the glues and quickly adjust the Overlay so the center slots are properly aligned. Blot any glue squished out and press the Overlay down along the glued section.


Wait a few minutes for the CA glue to fully harden. Remove the tape holding the Overlay in place, carefully bend it backwards and repeat the gluing process two Posts at a time until you reach the “L” end.

[TrainCat2]

The Overlays for Posts will be either PI for Post Interior or PE for Post Exterior. The difference is that Interior Overlays have slots that correspond to slots in the structure. Exterior Overlays will cover up those slots. Now, you did listen earlier when I advised that when you removed the triangles from the Truss Side that you sort them as to what they contain. It will make finding PI1 much easier. Locate PI1, remove from the fret and clean-up any tire remnants. Notice that the hole pattern can go only one way. Secure the PI1 Overlay to the Frame.


From this point on, it is assumed that the builder will clean-up any tire remnants once removed from the fret, has scruffed-up the back (shiny) side and test fitted the Overlay.

Although there are differences in Interior and Exterior Post Overlays, there are NO differences in the Overlays for the Bottom Chord Side. Installation sequences will always be Bottom Chord Side, Post and then Diagonals. Install Bottom Chord Side Overlay P1-2 ensuring the slots in the Overlay are correctly registered with those on the structure.


Like the Posts, Overlays for the Diagonals will be either DI for Diagonal Interior or DE for Diagonal Exterior. The difference is that Interior Overlays have slots that correspond to slots in the structure. Exterior Overlays will cover up those slots. Install Diagonal Overlay DI1.


Install Bottom Chord Side Overlay P2-4 ensuring the slots in the Overlay are correctly registered with those on the structure.

[Scottl]

This is so awesome.  Beautiful work on a magnificent bridge.

[TrainCat2]

I am showing this reference again to help in understanding the overlay sequence as I am going from left to center and from right to center. I will be adding the Overlays to the left interior first, then moving to the right interior, left exterior and right exterior.


Install Interior Post Overlay PI2


Install Interior Overlays PI3 and then DI2 can be installed


Install Interior Post Overlay PI4


Install Interior Diagonal Overlay DI3


The builder will need to adjust the lower “tip” of the Interior Post #5 Overlay to fit where the Gusset Plates protrude. This adjustment is not needed on the Exterior P5 Overlay. Be sure all slots are properly registered when securing the Overlay. Install Interior Post Overlay PI5. Test fit the Overlay for DI4. There are slots near the junction of D4, P5 and the Top Chord as well as in the middle of D4. I have found that some minor filing was required for a perfect fit on some of the pieces depending on how close I registered the surrounding Overlays.

[TrainCat2]

Now we are working in the cantilevered part of the Truss Frame. Remember, the sequence is Bottom Chord, Post and then Diagonal. Secure the Bottom Chord Side Overlay between P5 and P7. This will be marked as P5-7. There are slots in the Overlay to be able to fit between the protruding Gusset Plates at P5.


Install Interior Overlays PI6 and then DI5 can be installed


Secure the Bottom Chord Side Overlay between P7 and P9. This will be marked as P7-9.
Install Interior Overlays PI7 and then DI6 can be installed


Install Interior Overlays PI8 and then DI7 can be installed

[TrainCat2]

Secure the Bottom Chord Side Overlay between P9, P10 at the center of the Truss and P9 of the right half. This will be marked as P9-10-9.



Install Interior Overlays PI9 and then DI8 can be installed


Install Interior Overlays PI10 and then DI9 can be installed


At this point, you have to perform the same operations on the right half of the Truss Frame working from P1 on the right to P10 in the center.

[TrainCat2]

Now that the sides Overlays are attached, the bottom Overlays for the Top Chord are next. Start with the Overlays between P1 and P2 (TCLC P1-2), P2 and P3 (TCLC P2-3) then P3 and P4 (TCLC P3-4). Test fit to be sure the Overlay will be orientated the correct way so the oval lightning holes will align. Some slight trimming may be needed on one end of the overlay to get things aligned. I found had to trim 15%-20% of the time and no more that 1/64 in.


From this point on, it is assumed that the builder will clean-up any tire remnants once removed from the fret, has scuffed-up the back (shiny) side of the Overlay before securing to the Truss Frame. Turn the Truss Frame upside down where it is easier to work on the bottom of the Top Chord. Here is the Overlay secured between P1-P2 and P2-P3.


Here is another view of the Overlay secured between P2-P3 and P3-P4.


Test Fit the Overlays between P4-P5 and P5-P6. It is best to work two Overlays at a time form this point on.

[Scottl]

A work of art in the making.  What do you suggest to use to trim these thin flat pieces to prevent distortion?