Before I go too much further I want to make some corrections to the drawings. Now that I have a print out I can see some things I need to fix.
On drawing #1 of the trusses, some are two truss sets, some are one. But they are different from one side to the other. So I'll need to mark these on the drawing.
The nbw's on the base of the bridge are holding rods and are not bolts. These need to be the 3" variety and need to be increased in size on the model, like the ones on top of the bridge.
Align nbw's on the base with the nbw's on the truss sides. They should all match, but a few don't.
Normally I do this way before I'm this involved with a model. But I like this bridge and would build it anyway, so I'll push on. One thing I'd like to do is to pre-judge it (yes I know I haven't built it yet) so that I can get a rough idea of how it would score. This way I know if I have a chance at a Merit Award, or if I should start working on scratchbuilding 200 nbw castings!
Construction: This model is a bit more difficult than others due to the angles of the bridge trusses. Great care will have to be given in order to get them all straight and on the bridge beams. A judge will look for glue, fuzzy wood, straightness, alignment, and NBW placement. I would expect it to be classes as moderately complex on the grid, and I would do a very good job of assembly. This would score 25 points.
Details: This model will be 100% detailed, which is good. Spiking the rails, all the NBW's and the wood finish should do very well. I'll need to make sure the rail sections are cut and spliced at 39' intervals. On the grid I would say it would be classes as extensive detail, and evenly between easy and hard to add. Truss rods are tough! This would give me a score of 17 points
Conformity: The bridge is supported by excellent documentation with several photos and a complete set of drawings for assembly. It is very prototypical and matches the photos. I'll be sure to mention the errors in the original plans and other models. While some of the timber sizes may not be exact, they are very close and would have been exact if they had known dimensions. Wood is wood, metal is metal with the exceptions of the NBW's. On the graph I would say it is completely prototypical and almost extensive for a score of 21 points.
Finish & Lettering: It is hard to score lettering points on this bridge as there isn't any really. The finish will be excellent as I'm very good at staining and weathering real would and duplicating rust. Weathering will be the critical item here. I'm thinking simple and better for a score of 16 points.
Scratchbuilt: Drawings will be provided and the model is almost completely screatchbuilt with the exception of the nbw's and the turnbuckles. I'm not really sure if a judge would call this Moderate or Complex, so we'll use Moderate and Completely Scratchbuilt. This will yield a score of 13 points.
That is a good potential score! I could build the nbw's and turnbuckles from scratch, but they may wind up hurting me instead of helping me, so I won't bother. Construction will be the place I lose points if I don't do a good job on the assembly and cutting of the wood. But I have 4.5 points of room to play in and usually prefer 5. That should get me a merit award! Let's finish the drawings and build this sucker!
Ok...confessions of a rubber gauger. I normally understand the scale that I'm working with at the time, but occasionally I get surprised. Like today.
I have layouts in HO and On30. I also build models in S and have friends with N scale layouts. So I'm always switching back and forth. Sometimes when I've got a few HO and O scales projects going on at the same time I don't stop to think what size the model is going to turn out to be.
After waiting a few days because I ran out of toner, I finally got to print the O scale Howe Truss Bridge drawing out in full scale. Crap! It's huge! After spending days drawing it I guess I just never really thought about how big this silly thing is. Its over 16 inches long! Now, I should have known that, as I drew the damn thing. But it just never sank in. Same with ordering the lumber (which I went ahead and did Sunday afternoon.)
But I'm surprised. Actually, this bridge will look better in HO. In O it really will show any slips in the construction. Also, I can use it. But I don't want an 85 point bridge! Double crap.
Howdy! A quick correction before we start. I realized later when looking at my timber stock that I had incorrectly drawn the bridge base timbers at 12" deep, when they should be 18" deep. This has been corrected. This is what I don't like about making drawings. One little mistake will cost you lots of time and material. Be careful!
F. Draw the bridge base. The bridge base is the surrounding frame that joins the two truss assemblies. These require strength and squareness. I first started with the long beams and then the cross members. While looking at Wolfgang's model I noticed a gap in several spots. This is when I started getting concerned that nothing was holding the bridge together from side to side. Going back to Harry's drawings I realized that he left out the cross members. This is something a judge would catch easily. The reason it happened is probably because the timber size for these pieces is not listed on the drawings. When making drawings step back a second and ask "would this really work?" or "if I'm building this how would the engineer actually build it?" Little thinks like cross beams stick out like a sore thumb. He left the tie rods on the bottom out, too. Never build from someone else's model, but learn from what they did.
G. Draw in the details. Same as the previous section we need to put in the tie rods and the nbw's. We've put a section of the truss upright in the drawing so that we can match the nbw's to the tie rods. This points out that I drew the nbw's in the wrong size, so those will have to be corrected. Are you starting to learn that I'm not a draftsman or engineer?
H. Make a list of materials needed. This time we have to keep in mind that the truss sides are already built. We only need the new materials.
That's all for now. Next time we'll start on the upper deck and put in the outriggers. If you know the proper name for these things, please let me know. Is it a queen post?
So here is where I am with the drawing. Determining the dimensions from the photos has been rather difficult, so I'm staying close to Harry Brunk's drawing. When I finally evaluated the pitch of the trusses (35 degrees) I was able to draw in the trusses and figure out the rough length. Seems Harry's drawing is not that far off. Will I ever be able to draw it precisely? No, I'm afraid not.
Click on Drawing to Enlarge
B. Set up the drawing. At this point I decide what scale to draw the drawing in and set up the Cad drawing space. We'll draw it in O-scale since I can actually print it out full size. I'll reset the grid (the graph lines) to be one foot apart, with a darker four foot line for reference. I'll make the whole drawing area 70 feet long which gives me extra room for notes and dimensions. Then I'll set the layers of the drawing. We'll have the main layer (turning of the track component option), dimensions layer and a text layer. I always keep the text separate so that I can remove it easily for drawing. The last stage is to put in my drawing text block that tells what the drawing it, the scale, who did it and the revision. As I draw I save the file like this. For starters I use 1.001. The first one is the major revision number. The next three numbers are the drawing numbers. As a rule I save a new revision drawing every 15-20 minutes, or when I make a major change in the drawing. The file is now saved as Clear Creek Howe Truss Bridge 1.004 since I've made a few mods to the drawing already trying to figure out the length. For more information on Cad drawing I recommend you join one of the many Cad specific Yahoo groups.
C. Draw the side truss frame timbers. As this is probably the most complicated part of the drawing, so we'll tackle it first. This will be the diagram for building both side truss frames and we'll build on the drawing so it must be very accurate. One thing I like about making my own drawings is that it forces me to understand the construction and to build the bridge in my head. Assembly goes much faster this way and I make fewer and less costly mistakes. We won't need the rod trusses underneath or the
D. Draw in the details. I like to complete detail a model piece while I can keep it flat on the table. It is easier to drill and glue on a horizontal surface. So I'll go ahead and draw in all the nbw castings. There will be TWO sides no, an OUTSIDE and an INSIDE. That is the fun of a Cad system because it is easy to copy and paste. First I'll have to draw an nbw or two, then some side views, then just past them in place. One of the things you have to watch is "what am I connecting with these bolts?" While checking the picture vs the photos I've already found that along the top beam there should be two nbw's between each truss, not one. So we'll correct it on our drawing here.
E. Make a list of the materials needed. Since I'm building this in component sections and am familiar with the parts right now, I'll go ahead and make a list of materials and put it on the drawing. This makes it into my own kit.
Material for two truss side frames.
9 x 18 - 400 scale feet (100 inches)
9 x 9 - 900 scale feet (225 inches)
3" nbw - 28
2" nbw - 100 (some extra)
Brass (Piano) wire - 168 scale feet (42 inches)
That's all for today. We'll start on the base of the bridge tomorrow.
As I'm doing this one I thought I'd blog about HOW I do a project, from beginning to end. Magazine articles generally can't cover 100% of a project because it would turn into a book. Since I'm still sick with bronchitis the only thing I can do is write... here we go.
Step 1. What do I want to build?
I know I want to build a bridge. While I need it for my AP Structures list, I also like wooden bridges and have always wanted to build one. So this project is a wooden bridge.
Step 2. What kind of bridge?
The bridge has to be something interesting and challenging, otherwise I'll lose interest and it will never be completed. It also has to be able of scoring 87.5 points for an AP Merit Award in an NMRA judging. This means it has to be rather complex. A trestle might accomplish this, but I've built lots of trestles. I need something more difficult.
Step 3. Search for a prototype.
All modeling should start with the prototype. Many models that I have seen have been built from seeing other models! While I'm all for freelancing and imagination, to really score Merit Award points you should pick a good prototype. To me, reproducing something that exists (existed) is the most challenging of all.
Having a good home library of railroad books is a blessing. I have a library room with four large bookcases fill with train books, a comfy leather chair and a good light. A large stack of books will be pulled off the shelf and I'll start looking at pictures. For a bridge with a lot of character I often turn to the narrow gauge railroads who often had to build with what they had. One of my favorite books is Up Clear Creek on the Narrow Gauge by Harry Brunk, a professional illustrator and artist. His sketches are fantastic and he is a model builder, so the information for modeling is usually all there.
While browsing through the book (it is actually a lengthy collection of his famous magazine articles) I found just the bridge I'm looking for. The Colorado & Southern Railroad had a wooden (timber) Howe truss bridge spanning Clear Creek in the Clear Creek Canyon. See the picture below.
Step 4. Evaluate the Prototype as a Model
Now that I might have a prototype I give it the acid test, which is a battery of questions in order to decide if I'm going to build it or not.
A. Do I like it enough to spend hours constructing it? Yes. While it is complex looking, it is more repetitive than difficult. It is attractive and interesting.
B. Can I use it on my layout? Yes. Generally I don't build things that I can't use on my layout. I used to build structures for pay and put myself through school doing it, but no longer. Each piece that I construct has to be either for the layout or to build my skills for a bigger project in the near future.
C. Can I build it? Yes. This is the real test. Is my ego bigger than my skills? In this case no, so I have a good chance at success. There are a lot of pieces, but not anything requiring skills I don't have. I did find on line other modelers that successfully built this bridge, which is another indicator of success.
D. Do I have enough information? Yes. This is something I always ask. Sometimes one photo is enough. This one is a little more difficult. While Harry gave us some nice drawings, they are NOT plans, which is different. Some of the key dimensions are unknown, such as the length and height of the bridge. Harry even admits that if you want a more accurate bridge, you may have to go back to the photos. My next step is to jump on the computer. A few hours later I had more photographs and several shots of models of the bridge. I even conversed with a fellow in the UK that built one and got some pointers from him. The last step is to send off a request to the NMRA's Kalmbach Library for which I was rewarded with five pages of photos. Yes, we can make drawings from this.
E. Can I make a good set of construction drawings? Yes. I'm not talking magazine drawings but construction drawings. These will allow me to cut materials accurately and assemble them in the proper fashion. They can be as simple as graph paper sketchs or as complex as 3-D cad drawings. In this case I need the extra points and will produce a set of 2-D Cad drawings.
F. Are the materials needed readily available? Yes. Simple wood timbers and nut-bolt-washer castings, along with turnbuckles and wire. All available by scratch or the local hobby shop, which is Trainmaster Models.
G. Can I afford to build it? Yes. This is a VERY important question. When you look at a kit vs. a stractbuilt project you often THINK that scratchbuilding is cheaper. This is not the case in most projects. A buck here, a buck there really adds up. In this case I ran the numbers and don't believe that the cost will exceed $30. Details are what you have to watch!
H. How much time will it take? 20 hours. Wow! Really? Actually it will take more than that. For instance, just doing the research I've spent 5 hours and haven't even gotten a good start on the drawings. Do I care? No, but there are opportunity costs. If I'm building this, I'm not building something else.
I. What skills will I develop or learn? Precision. This is always good to ask yourself. Every model should be a challenge in some way or other. For this one I am trying to develop a higher level of precision. Attention to the fine details is important as I progress on to more and more difficult projects. The drilling of holes and making the angled supports uniformly straight is tricky, and may require the use of jigs for a higher level of precision.
With all those questions answered in a positive light, time to move on to the next step.
Step 5. Analyze the Prototype. I've gotten the photos, sketches and documents related to the bridge. I'm still missing some precise measurements, but we'll extrapolate them from the photos. With large printouts of each document I carefully scan the model. Using MS Word I've started a document to capture information. That board is crooked, that board is broken, there are four bolts on this side, etc. One thing I really noticed was the bridge foundation as one side is concrete and the other is build of crossties. One of the tricky things is NOT looking at someone else's model for prototype information. Wolfgang built a nice model, but he did it from sketches, not drawings, and some things don't look right. I'd like a more precise model so I'm going to have to throw Harry's beautiful sketches out the window and draw a set of plans.
Step 6. Determine how to build the model. This is the step where we sit back and go "if I were going to provide this to the public as a kit, what would the kit look like and how would I build it?" This is a very important step as a mistake here can cost you time and materials. Still, no matter how well you do, you won't be able to do this perfectly, so do wait for perfection.
For the bridge, I see it as several components. Each side is a component, the bottom is a component, and the track and ties are one component. So we are looking at four sub-assemblies. If I build the bridge supports, that is five. Great! This tells us how to build it. The sides are identical, so we can build them in tandem. The ties/rail can be built separately and then added to the model at the end. The toughest part will be the bridge base, which can't be done until the sides are ready. Ok, so we build the sides, then the base, then the supports and then add the track.
Step 7. Evaluate Drawings. What drawings do I need? Well, they should match the components listed above. We'll need a side drawing (top and side), a bridge base, a track drawing and then the supports (two since they are different). We'll do these in Cad since we'll want to get AP Points and because I'd like to share them with people who might want other scales.
Step 8. Begin the Drawings. This is where we lose people. The armchair guys never get past this point. But we are. I've begun the drawings on 3rd Plan It Cad. Not the best in the world, but what I happen to have and know. Like other things, there are several steps here.
A. Determine the overall dimensions of the model. This is a problem right off the bat as I don't have a full length or height dimension. Will have to extrapolate it. Harry Brunk's drawing appears to be roughly 1/8" to the foot. That makes the bridge 66'. I have a picture with a man standing on the bridge. It scales out to about 50'. Big difference. I'll have to work on this. I'm also having trouble determining the angle of the supports.
While at home laying in bed and coughing I've had plenty of time to plan and think. Tried working on models but the cough medicine makes it hard to focus.
The mail came today with my information from the wonderful NMRA Kalmbach Library. If you don't use this asset, you are REALLY missing out. Our researcher Thomas Mossbeck sent me a stack of photos of the Colorado & Southern's Clear Creek Canyon Timber Howe Truss Bridge. So nice to have good prototype photos sent to you for just and email and a $3.25 copying and postage fee. Especially when owning the books would have cost me $200.
I really got interested in this bridge from Harry Brunk's book called Up Clear Creek on the Narrow Gauge. It is one of the most fun books I have and is full of his fantastic pen & ink drawings. While not simple to build, it really lends itself to a great scractchbuilding project and has the potential to earn the points I need for an AP Structure. You gotta have one bridge.
Armed with photos and diagrams and Brunk's rough drawings I'll make a set of scale plans that I'll share with you soon. We'll build this to On30 standards and publish the work on my Okefenokee Railroad Blog since I'll probably use it on that railroad.
