(note: a portion of this support structure was built during my previous layout, so you will see that layout as the background to the photos)
I thoroughly studied the scaled drawings found in the December 22, 1900 The Engineering And Mining Journal article where this tipple structure was fully described. It includes a scale ranging from 0 to 25 feet, which I copied and rotated 90 degrees and then placed two copies next to the vertical columns. As near as I can tell, the floor of the tipple was supported by 37-foot tall columns, resting on the concrete foundation blocks. The text describes these columns as having been made out of two 10" C-channels welded together to form an H-column. To build these columns, I bought a bulk pack of Evergreen's C-channel, part #265. These are 0.156" wide, which scales out to 10 inches in S-scale. These strips are 14" long, which scales out to 74 feet in S-scale. However, because the interior "floor" of my tipple building is inset vertically from the walls of the building, some of my columns will need to be longer than 37 feet, so I won't be able to get two columns out of each pair of C-channels. So, by buying the 100-pack (bulk) pack, I can glue two together to create the 44 columns I need, and have a few strips left over for the horizontal members. Anyway, this is a massive project, so I realized that I needed to build the basic structure of 11 columns, four times. To make an attempt at them all coming out to be the same, I decided to invest in the time to build a jig. I found two sheets of plywood left over in the garage that were nice and flat. I clamped them together to form a 1.5" thick board, and drove in a number of screws to hold them together. This made absolutely sure that they were, and remained, flat.
(external link: Evergreen Styrene)
As you might be able to barely make out from the photo, I drew vertical lines where each of the columns are to be on this jig. I based these off of the foundation blocks I already have on my layout, so that they are a good match.
Since I will be gluing two C-channels back to back to form one column, the other purpose of the jig is to allow me to insert those two pieces of strip styrene into the grooves, and then apply glue to the C-channels. This is actually harder to do than one might think. The C-channels in and of themselves are actually still quite flexible, so a jig is really required it you want straight columns. This jig makes it possible. So, I cut my jig on the tablesaw so that all of its edges were perfectly square to one another. I then used the tablesaw to cut the grooves you see in the photo. I cut the grooves just slightly deeper than the width of a C-channel strip, so that both ends of the "C" of the C-channel are pressed against the edges of the grooves. The kerf of my tablesaw blade is just a 1/32nd smaller than the S-scale 10" C-channel strip is deep, so by moving the tablesaw fence over a hair, I got a groove that holds the two C-channels back-to-back reasonably tightly for me to apply glue to their adjoining backs. This was really the only bit of guessing I had to do when cutting the grooves; if the grooves are too wide, the C-channel sub-assembly will be too loose; if too narrow, then the two C-channels will not fit, obviously.
There are three rows of horizontal sections that fit between the columns, so I cut those out in the jig in a similar manner. This will allow me to construct the basic shape of the trestle structure in the jig. (We were hit by a major winterstorm, February 2021, so progress was halted on this for the next 5 days)
With the jig completed, I could start to build the first of four trestle sections. I inserted pairs of C-channels in each groove, with their "backs" toward each other, to form a shallow H-column. I could then apply glue to their joints. Since the columns don't need to be as tall as the jig is wide, the extra lengths of the material can just hang loose out of the other end. The front edge of the jig is my reference edge, so I am using a metal weight to press the C-channels against.
The left-over sections were then temporarily inserted in one of the vertical grooves so that I could apply glue to them as well. When that was done, I carefully measured the distance between each of the vertical columns and cut a section off using the NWSL Chopper. These horizontal beams could then be placed in the jig and glued to the vertical columns. This photo shows the entire sub-assembly built.
While the jig is a good idea, at some point in time the assembly has to come out of the jig. Since I cut the grooves rather tight, it was a bit of a challenge to get the assembly out of the jig. I used the two pieces of strip wood you see in the photo as "chisels". I filed down one of their ends to look like a chisel. I could then pry them in between the styrene assembly and the jig to lift the assembly up.
Since the horizontal beams are only edge-glued to the vertical beams, and only their "C" ends are glued (and possibly only the top one at that), needless to say, the fully-assembled structure turned itself back into a sub-assembly "kit", as shown in this photo. I knew that that was going to happen, but I didn't know how I was going to deal with that, and just how bad it would be.
So, I flipped the jig over (its back side is smooth with no grooves), and then carefully re-assembled the kit version. The weights make sure that the assembly stays as flat as possible, and I had to carefully measure and verify that each loose piece went back into its designated spot. Again, this is still doing edge gluing. Note that I used a 4-foot long metal level as my bottom-edge guide. I clamped it down to the jig so that it wouldn't move as I was working on it. Between that and the weights, I was able to put the whole thing back together again.
Because I knew that the edge-gluing wasn't going to be structurally sound, I knew that I wanted to reinforce each joint once the basic assembly was put together. The newly edge-glued assembly held together, but I had to be very careful with it. I don't know how the prototype deals with these types of joints, but I decided to use a scale 6-inch wide 90-degree angle strip of styrene, and cut small sections of it off using the NWSL Chopper. The width of these small sections matched the interior width of the C-channels.
The idea is to then glue those corner wedges into each joint throughout the assembly. I still had the assembly flat on my jig, but it turned out to be very difficult to get the corner wedge to properly seat into the corner before I could apply the glue. The bottom edge of the C-channel raises it just high enough that the corner falls out each time. Since I have a bazillion of these to do, I had to come up with a quick and easy method to accomplish that. I tried several things, but I wound up with this metal angle bracket. I put that in the corner, and then placed the corner wedge on top of it with my pair of tweezers. I then used a toothpick to carefully guide it into the corner. I couldn't reliably use the metal pair of tweezers, because the styrene corner wedge is still a bit statically-loaded and so it would "stick" to the tweezers. A toothpick resolved that issue. Although it is a bit of a pain to have to constantly switch tools. Anyway, with the corner wedge pushed into position, I could then touch it with a small paintbrush loaded with glue to permanently seat it. I did that for every intersection on both sides, and that is what really made the whole assembly quite sturdy.
Here is a close-up of what one such intersection looks like. The other three areas of this intersection also have these corner wedges in them, and that is what gives this model structure its strength.
When it was all done, I couldn't wait to put it into its relative position to see what it looks like. The tops of the vertical columns still need to be trimmed to their proper length, with is about a real-world inch above the top horizontal beams. I will do that later when I actually get around to fitting the main building to the trestle structure. Next, I need to build three more of these. However, I learned my lesson, and I am going to update the jig by using a Forstner bit to make rounded holes at each intersection of the grooves on the jig. That way, I can apply these corner wedges while the assembly is still in the jig. It should make it easier to remove the assembly from the jig, and hopefully there will be no breaking of the glue joints in the process. If that works, then that will make the assembly of the other three much faster, and much easier. This first one took me 9 days' worth of leisurely hobby time to construct.
For a scale reference, I put a hopper car on one of the tracks. This is going to be quite an imposing structure when the whole thing is put together, probably much like what the real prototype was like when you stood nearby. By the way, I used metal squares to hold the assembly upright while I took the photos. Also, one further note; this sub-assembly is not anywhere near finished yet. I still need to put the diagonal bracing and their gusset plates in between the corners. But, now that I have this built, I will be able to take measurements and determine how much styrene strip material I need to complete that task.
Before building the second assembly, I improved the jig by using a Forstner bit to drill out holes at each of the intersections.
This allowed me to build the base framework in the jig, as before, but to also install the angle bracket at each of the corners of the intersecting pieces. When done, I let it cure overnight, and the next day I was able to remove the second assembly with no damage to the assembly. The construction time went from 9 days to 5 days, thanks to the jig's improvements. The third assembly is now almost finished, too. Then, one more, and this jig will have done its job.
This is just a quick photo of the four sub-assemblies completed, with the main building sitting in front of them. This is what I had completed when I decided to retire my previous layout, and start a new one.
So, here we are about two months later, and I am getting back to this project. Please note that this sub-assembly looks crooked, but I promise, it is nice and straight. The distortion is due to the camera and the angle at which I shot the photo. So, what I did here was (after studying the prototype architectural/engineering drawings) was to cut 2-1/2-foot square gusset plates, and attached them to each of the intersections where cross braces are needed (as per the prototype). I made these out of 0.010"-thick sheet styrene.
After trimming off some of the excess from the various plates where no cross braces are to be installed, I started installing the full-length cross braces. I made these using scale 4-inch I-beams. From the prototype drawings, I couldn't make out what shapes these cross braces had, but I could determine that they were 4" wide. I had a good number of 4" I-beams in stock, so I started with those. They are relatively strong for the small size, so I will continue to use them throughout for the cross braces.
Next up are the gusset plates that allow the other diagonal's cross braces to be installed. I made these out of scale 1.5-foot square styrene sheet. Since it is hard to balance these on the thin cross braces, I marked the center spot of the full-length cross brace, and then put a tiny dab of glue on that spot. I could then quickly apply and position the smaller gusset plate, and add a bit more glue once it was in position.
And this represents one sub-assembly with its cross bracing completed. There is more work to be done to finalize it, but I want to stay focused on just doing the cross bracing for now. This particular one has a flat top, because it is intended to be used as support for the exterior walls of the tipple building itself. The actual gussets are on the "interior" side of the structure, so that means that this particular sub-assembly will be used to hold up the right-hand side of the tipple building, when looking at it from the front of the layout. The next one I am working on will be its mirror image.
The four sub-assemblies are now built. One thing I have noticed is that the styrene seems to warp. I'll have to pay attention to attempting to correct that as I proceed.
The "open" sections, where the track passes through the structure, had corner braces in the two upper corners, so those still need to be formed and installed.
I made those out of strips of scale 5"x6" styrene. Since I needed to form 48 of these, I built a jig that holds two strips of wood, trimmed to the desired angle, with each "leg" being the desired length. I could then place a strip of styrene against the angled part of the jig, hold it in place by hand with the metal weights, and then file the ends of the strip to form the desired angle.
With the four sub-assemblies completed, it is now time to start connecting them with each other. After carefully measurements, I settled on the outsides of the two outside assemblies being 30.5 feet apart. So, I cut a 10" C-channel strip of styrene to that length and glued it to the top of the first sub-assembly (I am building these upside-down). I attached another strip on the other end of the first sub-assembly.
I then attached the other outside sub-assembly to the strips. Before going too much further, it was time to insert the two inner sub-assemblies. The question was, How am I going to keep them correctly positioned? I came up with this idea of using a section of blue masking tape, and applying three pieces of strip wood to it, such that the gaps (and ends) allowed me to correctly position the assemblies. The strip wood pieces each were a scale 9 feet long. I did not take a photo of this, but after the first use of this solution, I superglued another full-length strip of wood to the non-sticky side of the blue masking tape, over the back area of where the strip wood pieces are. That made the whole tape jig more sturdy, and made it easier to insert and remove repeatedly. This one tape jig lasted for the entire process of attaching the interior cross members, by the way.
The two inner sub-assemblies have their vertical columns stick up a bit, so I needed to place the whole assembly on two sections of leftover plywood. I also found that my styrene sub-assemblies were warping quite a bit, even though I built them in a flat jig. My only guess is that as I apply styrene glue (MEK), as the bond cures, it slightly pulls on the joints' members. Doing this a good number of times due to the complexity of the sub-assemblies, probably led to the slight warping. Nonetheless, I had to use all sorts of squares and metal weights to force the sub-assemblies to be straight again as I installed the cross members. The first cross members I installed are more of the 10" C-channel strips that could span the entire width of the support structure (these were based on locations of them as spotted on the engineering drawing of the prototype building).
Here is an overall view of the construction as it progresses. I had to build this on my desk, as that was the only space big enough for this structure and the needed tools and supplies. You can see the remaining 30.5-foot full-width cross members that still need to be installed.
This is a view of the bottom of the support structure over the open track area. There are two C-channels back-to-back across the four sub-assemblies. There can be nothing between them as that is where the track and equipment goes. I will have to force them to be the correct spacing and alignment when it comes time to glue this support structure to the layout.
Once the support structure was sturdy enough to be (carefully) moved, I couldn't help but temporarily place it on the module, to see what it might look like. What struck me was that, as I am building this support structure, focusing on the small details and parts, when the whole thing comes together, it looks quite impressive; it is just a massive web of "stuff". At the moment I took this photo, I only had the full-width C-channel strips installed across the four sub-assemblies. Each intersecting point needs cross members between them, which is next. While critical for the overall structural integrity of the building, they are going to be hard to see. I put the 40-foot box car in the photo to give a sense of dimension.