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The Bard Creek Railroad
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 Posted: Sun Dec 29th, 2013 10:36 am
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Milocomarty
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James, change the upper brackets for triangular shaped ones, no need for additional supports



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 Posted: Sun Dec 29th, 2013 03:01 pm
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jtrain
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Sorry, I don't quite follow. Do you mean instead of having a vertical column halfway between the back and the front of the module, make that support like a shelf bracket that connects from the 2x2 to the valance?



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 Posted: Sun Dec 29th, 2013 04:37 pm
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Milocomarty
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Yes, thats what I mean, use wedge shapes connected to your background support, bit like shelfbrackets but then upside down..



hope you see it a bit in this picture..



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 Posted: Sun Dec 29th, 2013 05:54 pm
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bill
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Is the primary purpose of the valence to provide lighting or to protect the module when other modules are stacked for transport? After many years in an HO modular group, being able to leave structures on the modules would be a plus, but I suspect the valence could be a problem. If there is no compelling reason to add lighting, would it be easier to create brackets that would bolt onto the ends of each module to provide the support for stacking and transport. With the light weight module structure, a simple bracket would be strong enough to support another module, especially if you could bolt the top module to the bracket that was also bolted to the bottom module. Just thought.

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 Posted: Sun Dec 29th, 2013 08:55 pm
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jtrain
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Martin,

Thanks for the photo, that helped me visualize what you were talking about a lot better. Those brackets would work, the only problem being that to transport the modules, I will need to stack them, but it is a design consideration none the less.

Thank you.

--James:java:



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 Posted: Sun Dec 29th, 2013 09:10 pm
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jtrain
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Bill,

Brackets were a thought for me too, but I decided to at least try and design a valance that will be sturdy enough to support 1-2 modules stacked on top of the first. Lighting and backdrop was the main reason to have a valance, as you pointed out. In every show I've been to in the Midwest, the lighting has not been adequate for folks who have limited vision and also for folks carrying cameras. To give a layout a decent amount of light would be very beneficial. So no, lightning isn't necessary, but it is a priority right underneath safety and durability, safety taking precedence overall. On top of this, the valance is visually pleasing and looks very professional, something that also ranks high on my list of elements I want for the layout.

The bracket idea is more or less my backup if spring arrives and I still haven't thought of a decent idea of having legs, bench work, scenery, backdrop and lighting all in one module. The benefit I see with all-in-one module design is the protection the modules give to the scenery and the fact that I won't need to carry around so many boxes full of trains, trees, power supplies, buildings, vehicles and people.

Will I solve the issue? Who knows, but I'm glad you and Martin have given me other options in case my idea doesn't quite work.

--James:java:



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 Posted: Sun Dec 29th, 2013 09:45 pm
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dennischee
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Hi James,
Folding legs built the same way as Martin's picture could solve your problem?
Just a thought

Dennis L:L:

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 Posted: Sun Dec 29th, 2013 10:30 pm
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jtrain
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Yes, that is generally what I had in mind for the legs as well, except perhaps I would add angled braces that stretch from about 2/3 the way down the legs and run towards the center of the module.

Thanks.

--James:java:



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 Posted: Sun Dec 29th, 2013 11:19 pm
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jtrain
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I've made a break through! After thinking about Martin's and Bill's comments, that got be thinking on how to better transfer weight from the valance to the layout deck and under frame. The main problem lies in the supports to hold up the valance. Originally I wanted to use cut plywood brackets in a squared off C shape to use as ribs that would support the backdrop, layout deck and valance all in one while simultaneously transferring weight from the top to the bottom effectively. Plywood alone is not strong enough to do this, especially with as much as 60-70 pounds of additional weight on top (assuming 1 module weighs 35 pounds and the modules are stacked three high in transport).

Here is how my thought trend has been going:

My idea -> brackets -> Bill's idea -> Martin's idea -> suspension -> bridges -> bridge types -> truss bridge -> truss frame -> truss bracket !BINGO!:!:

Finally get to use the light bulb icon!

Below is what I'm thinking of for brackets:



To keep weight down while maximizing stability and strength, Railroads as well as most other forms to transport utilize a truss bridge design for. Beam bridges are good for short spans, suspensions bridges are great for long spans, but truss bridges combine aspects of both.

One thing to consider is that there are three main types of forces acting on any bridge: tension, compression and sheer.

Tension is a force that attempts to bend or stretch a material in the direction of gravity. The ropes that hold up a swing are under tension.

Compression is a force that attempts to break or squish (for lack of a better word) a material. Columns are under compression, holding up a roof.

Sheer is a force that attempts to break a material along a line perpendicular The 'pin' in the link and pin coupler was always under a sheering force.

A rope or cable can take tension better tan most materials while wood products take compression better than most materials. Plywood, due to it's cross grain strength, can take both compression and tension better than dimensional lumber. Metal is best under a sheering force, or under tension.

Since I don't work with metal, that's out. Rope has no use for be either. So I'm stuck with wood. The key is to minimize any tension and turn it to compression. My idea is to make a sort of truss framework out of 1x2 or 1x3 and some 2x2 pieces of lumber which will transfer forces so that the majority of the lumber is under compression. The green represents compression and the red represents tension. All that force, when exerted on screws in each joint, will be under a sheering force. Since screw are metal, they will withstand sheering quite well if given a good hold and some glue.

I then cut out two pieces of thin plywood and sandwich the framework between the two pieces to make a solid bracket that is quite strong.

With that, I can simply add a light frame made out of plywood around the brackets to get my module. This should hold significantly more force than a simple bracket made out of plywood or dimensional lumber alone. Plus, the bracket has nothing sticking out making the shape awkward.



Each bracket is aligned as so, each connected to the others with plywood. To stiffen up the structure, I can add 1x2 supports where necessary along the plywood.



Here is a cross section of the module with the foam, backdrop and the plywood skin (grey perimeter).

And the full assembly, painted and ready for scenery:



So what does everyone think?

Again, Martin's and Bill's ideas are back ups, bu they are good ideas none the less. I will have to build one of these brackets to see how well they hold weight.

--James:java:



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 Posted: Sun Dec 29th, 2013 11:27 pm
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jtrain
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Oh yes, and one other thing. As long as I don't use too much lumber, the module framework should be relatively light. 1x2 lumber and 1/4" plywood isn't really that heavy, and most of the module will be made from just that.

I should say thought that this is what I predict, I'll have to test out the design to see for sure.

--James:java:



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