Did you say it came in a single and double track versions?
If so which one are you doing?
Look forward to your progress.
Frank, thanks for that reply. As you know, I overthink everything. [(-D]
I had considered what you pointed out about stress on the x-sections. That would certainly be true on a real bridge, but stress on an HO scale model??? [:^)]
Rich
Thanks, again, Frank. That is what I intend to do, as you suggested.
It is just that it will require a lot more careful cutting and sawing since the “mated” pieces will not exactly match. The X-bracing of both pieces to be mated will match, but the vertical end supports of each piece will not match since the overlapping pieces are of different widths, thanks to this 60/40 design.
It wouldn’t matter if I settled for the length of the truss span (as is) out of the box, but I want to add two X-braced center sections to lengthen the bridge span, so that complicates matters.
Rich
Yep, it is available in both versions, single track and double track. They are the same design except that the two-track version is wider than the single track version. I am building the double track version.
Rich
Whether the kit’s design is 60/40 or 50/50, the mating surfaces of the two sections are a face-joint, with each side of those verticals representing half the thickness.
To add the additional X-panel to each side, simply cut them from the donor bridge, then cut/file the just-cut vertical member to half of its original thickness. The mating edges of the bridge being lengthened are already half-thickness, so all that’s needed it to lay the parts on a flat surface and cement them together.
I would, however, use a continuous piece of strip styene, of suitable width and thickness, over the entire length on the top and bottom members of the lengthened bridge, before adding the upper and lower flange pieces (parts 6-7-8-9).
These two posts sorta confused me…
I take it that the two X-braced sections to which you refer are not to lengthen the bridge by two panels, but rather one for each truss. Otherwise, you’ll need to order a third kit. [swg]
I do agree with Frank’s suggestion regarding the use of full-length I-beams for the deck, though.
Wayne
Wayne, I do need to order a 3rd kit.
Rich
I attempted kitbashing a pratt bridge out of several kits thinking it would be quicker and easier than a scratch build. It was a painstaking experience. Very tedious, time-consuming and more expensive. I ended up scratching the project and starting all over scratch building. It was then I successfully completed the bridge.
Scratch building a bridge is really not that difficult with quarter inch foam board, a template, wax paper and T pins. I didn’t have a template on my first build or any of them for that matter. Bridge design is not that difficult either. When you break it down it’s just simple repeating geometry and really a lot of fun to scale out.
This was my first scratch built bridge. It is not a pratt but it easily could have been by changing only 4 members on either side. It is an N-Scale Bridge. HO would be much easier, not as tedious.
When I built this bridge, styrene was new to me. I didn’t know how to pick it and I was not familiar with any of the members.
Had I done a little more research before the build, I could have done a lot better job. I am still waiting for a rainy day to replace the 12 angled members on the top of this bridge to thinner members.
Scratch built bridges as time-consuming, they are a lot of fun though. They are not that difficult.
Respectfully TF
Wayne, the point that I was trying to make in that passage that confused you is the the mating center x-braced sections are not an exact match. There is an overlap so when the two sections are mated they do match, but the actual dimensions of those two mated center x-braced sections are slightly different from one another, out of the box. All of the other sections are exact matches in dimensions.
Rich
Before I bought the Walthers kits, I downloaded the instructions and briefly reviewed the illustrations. I mistakenly thought that there were four sections to form both sides of the truss span, as seen below.
But, there are actually 8 parts involved. The previous illustration shows only one side of the truss span.
The photo below shows the actual four parts needed to form one side of the truss span. Notice the 60/40 split.
The next photo shows the parts joined to form one side of the truss span, as the kit is intended to be built.
But, I want to lengthen the span so I need to add two additional center x-braced sections, as shown in the drawing below:
I’ve been watching, could you alternate the sides, using the X pieces, to get the overall length the same? trying different combinations of X peices butted, one from one side, and one from the other side, to get the length?
Is scratch building the piece an option? instead of buying another kit?
Mike.
That is a very good question, Mike. Let me study this a bit more to see if if is feasible to build a center x-braced section to provide the additional length that I need along the truss span. I had not thought of that as a solution.
Rich
Rich. After seeing your photos, now I understand. It is possible to achieve what you are trying to do without buying another kit but it’s going to take some time and patience. If your time is valuable the third kit might be the way to go.
Store bought styrene does work with bridge kits if you need to lengthen anyting, I’ve done that. When I was trying to kitbash, it was turning a Warren truss Bridge into a Pratt Bridge from kits because it was the right size. I needed a Camelback Pratt for the center section of a three-section series bridge. The problem was the gusset plates being different sizes that become a big problem. These two truss sections are the same sections, the one is just modified. I was 90% there but I said screw it because I had five more to do.
At least I see what you’re trying to do now. Honestly I would have to agree with Wayne. Save yourself a big headache and buy the third bridge. You will thank yourself[Y]
I foresee you still have a challenge but you can do it. You may want to run a steel rod under your tracks when you get the bridge done. Those HO loco’s sure are heavier than the N ones.
TF
TF, thanks for that advice and, by the way, very nice job on that bridge in the photo.
Yeah, I think that the 3rd bridge is the way to go because it is going to be difficult to scratch build the additional center section(s).
Rich
OK, so just to clear this up in my own little mind, the X pieces are the same size, so with the second kit, you 2 more X pieces, for a total 4, but you want to make the span longer yet, so you need a total of 6, X pieces, 3 for each side?
I think I musunderstood you as saying the X pieces weren’t the same size, is why I suggested the mix-n-match.
The bridge you want to build, is like Frank’s? Do you scratch build the towers, or are they from another kit?
Mike.
I have spent a good part of the day studying the various parts of the bridge, making measurements, and preparing drawings. What complicates this bridge, particularly because I want to lengthen it, is the fact that the sides of the truss span are a 60/40 arrangement.
Each side of the truss span consists of four pieces, a left side and a right side outer section and a left side and a right side inner section. The left side outer section is mated to the left side inner section, but these mated sections are different lengths. Same for the mated right side sections.
The center x-braced outer and inner sections are the same overall size, but unlike the other other sections of the truss span, the vertical ends of the center x-braced section are not the same width. One end is narrower in width than the other end. So, when the outer and inner sections are mated, the narrow end of the one section is mated with the wide end of the other section, and the wide end of that section is mated with the narrow end of that section.
Whew, that is a mouthful. It is all the fault of the 60/40 arrangement.
Well, as I just explained, dimensionally they are the same size, but because the vertical ends of the x-braced center section are different widths, when the outer and inner sides are mated, the mated ends are different widths.
Frank built the CMR vertical lift
Thanks Rich for taking the time to explain, again! I’ll have to look at the instructions again, just for my mind. It’s crazy that each side is two pieces, being an inner and outer.
Keep us posted, and lets us follow along!
Mike.
It’s not unusual for Walthers to design railroad bridges with inner and outer sections, but it is unusual to design a 60/40 arrangement. Any other Walthers railroad bridge that I have built was a 50/50 arrangement where the inner and outer sections mated exactly with no overlaps.
The photo below shows the 8 sections required to complete both sides of the arched Pratt truss bridge.
The photo below shows the 4 mated sections required to complete both sides of the arched Pratt truss bridge.
The photo below shows the 2 completed sides of the arched Pratt truss bridge.
Now, I need to add the two additional center x-braced sections to lengthen the bridge to 30" from the original 23".
Rich
And when you do, you can file the vertical members, where necessary, to keep them all the same thickness, or, where they’re too thin, add appropriate strip styrene as a filler between the mating kit pieces.
Wayne
Wayne, all of the vertical members will be the same thickness. Are you speaking of the width of the vertical members?
Rich
That’s even better, Rich. In the last photo, the joints between the two sections looked a little thinner, although I do realise that they’re not yet cemented together.
Wayne