OK, I don't own a caliper, but it does appear that all of the vertical members are the same width at 3/16". So, I see your point, Wayne. I need to cut and trim the vertical ends of those additional x-braced sections so that they have the same resulting width as the unmodified vertical members. I believe that my plan for cutting and trimming these additional sections will result in identical widths. But, we shall see.
Rich
Alton Junction
doctorwayne 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
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
doctorwayne richhotrain ....I need to add the two additional center x-braced sections.... 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
richhotrain ....I need to add the two additional center x-braced sections....
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.
mbinsewi 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.
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.
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".
Keep us posted, and lets us follow along!
Mike.
My You Tube
mbinsewi 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?
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?
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.
mbinsewi I think I musunderstood you as saying the X pieces weren't the same size, is why I suggested the mix-n-match.
I think I musunderstood you as saying the X pieces weren't the same size, is why I suggested the mix-n-match.
mbinsewi The bridge you want to build, is like Frank's? Do you scratch build the towers, or are they from another kit?
The bridge you want to build, is like Frank's? Do you scratch build the towers, or are they from another kit?
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. 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
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
mbinsewi 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.
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?
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:
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.
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, I do need to order a 3rd kit.
richhotraint 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.
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...
richhotrain...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.
zstripeWhat You would do, is add an X section to bridge part 4 and 2 or two X section per part. Then You would reinforce the bottom deck with full length I- beams for the deck
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.
I do agree with Frank's suggestion regarding the use of full-length I-beams for the deck, though.
railandsail Did you say it came in a single and double track versions?If so which one are you doing? Look forward to your progress.
Did you say it came in a single and double track versions?If so which one are you doing?
Look forward to your progress.
zstripe richhotrain What I fail to understand though is why the kit was designed with that 60/40 arrangement. That complicates the insertion of additional center sections. So, I need to further analyze how to pull this off. I invite all comments and suggestions in this regard.
richhotrain What I fail to understand though is why the kit was designed with that 60/40 arrangement. That complicates the insertion of additional center sections. So, I need to further analyze how to pull this off. I invite all comments and suggestions in this regard.
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.
zstripe richhotrain What I fail to understand though is why the kit was designed with that 60/40 arrangement. That complicates the insertion of additional center sections. So, I need to further analyze how to pull this off. I invite all comments and suggestions in this regard. Rich, Like I said in My PM.......The X sections are the main vertical stress part of the bridge. The 60/40 arrangement was to offset the stress on the X sections where the girders would meet, instead of having them directly over a joint, like in a hinge. Sort of like a reversing section on track where they tell you to stagger the joints......not directly across from one another. What You would do, is add an X section to bridge part 4 and 2 or two X section per part. Then You would reinforce the bottom deck with full length I- beams for the deck as I also suggested in My PM. Don't over think this.....It's not that hard. Take Care! Frank
Rich,
Like I said in My PM.......The X sections are the main vertical stress part of the bridge. The 60/40 arrangement was to offset the stress on the X sections where the girders would meet, instead of having them directly over a joint, like in a hinge. Sort of like a reversing section on track where they tell you to stagger the joints......not directly across from one another.
What You would do, is add an X section to bridge part 4 and 2 or two X section per part. Then You would reinforce the bottom deck with full length I- beams for the deck as I also suggested in My PM. Don't over think this.....It's not that hard.
Take Care!
Frank
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???
Brian
My Layout Plan
Interesting new Plan Consideration
richhotrainWhat I fail to understand though is why the kit was designed with that 60/40 arrangement. That complicates the insertion of additional center sections. So, I need to further analyze how to pull this off. I invite all comments and suggestions in this regard.
gmpullman richhotrain By the way, how do you know that the left and right sections are 60/40 and 40/60? All I'm implying by that is that the joints of the side sections are offset. 4 panels + 3 on the right side (what I'm calling 60/40) 3 panels + 4 on the left side (what I'm calling 40/60) in order to off-set the joint. W_prattruss by Edmund, on Flickr Cheers, Ed
richhotrain By the way, how do you know that the left and right sections are 60/40 and 40/60?
All I'm implying by that is that the joints of the side sections are offset.
4 panels + 3 on the right side (what I'm calling 60/40)
3 panels + 4 on the left side (what I'm calling 40/60) in order to off-set the joint.
W_prattruss by Edmund, on Flickr
Cheers, Ed
The good news is that the center section with the X-bracing is perfectly rectangular, so it will be geometrically possible to add one or more additional center sections to increase the length of the bridge span.
What I fail to understand though is why the kit was designed with that 60/40 arrangement. That complicates the insertion of additional center sections. So, I need to further analyze how to pull this off. I invite all comments and suggestions in this regard.
doctorwayne Rich, are you going to build it as a skewed bridge, like the prototype? Wayne
Rich, are you going to build it as a skewed bridge, like the prototype?
j. c. rich is this the bridge your refering to ? http://bridgehunter.com/il/cook/bh50843/
rich is this the bridge your refering to ?
http://bridgehunter.com/il/cook/bh50843/
Here is the detailed look at the bridge.
https://historicbridges.org/bridges/browser/?bridgebrowser=illinois/sblift/
rich is this the bridge your refering to ? http://bridgehunter.com/il/cook/bh50843/
selector http://pghbridges.com/basics.htm This site has been in my 'favorites' since 'bout Day One.
http://pghbridges.com/basics.htm
This site has been in my 'favorites' since 'bout Day One.
The bridge that I am thinking about modeling is the PRR vertical lift bridge in downtown Chicago. It is actually a Parker Through Truss which is a modified Pratt Truss. It is illustrated in the drawings from that link as a Parker "Camelback" (Pratt) Truss, which is the Walthers model.