scratchbuilding bridge help


toomuchfun

New Member
hey folks!

I am wanting to scratchbuild a bridge. I am finding lots of pictures on the web, but scarce amount of true dimensions. The bridge I would like to build is a camelback through truss bridge and I would need it to be around 4.5 feet long spanning my work bench.

Now for the kicker... I would like to use balsa and plywood instead of plastic. I don't mind the extra work, but I am trying to avoid the costs involved which could end up being too much. My wonderful wife has me on a "beg borrow or steal" budget... :(

Thanks for any help!

too much fun!
 
one last thing

Oh, one last thing...

I also need some info on a wooden stringer rural overpass. I seem to remember that it had 5 sections but all I can find are three section overpasses. These were built in the 1930's from what I am gathering and it was a very typical design to allow farm traffic on gravel roads to bridge over a single or double mainline. My mom and dad carved their initials in one close to where my mom grew up in the 1950's and I thought it would be great to build one on my layout (mopac and mkt and any other missouri rail of that era) to supprise them! Thanks for any help!
 
Just a note:
Don't use balsa, use basswood and/or spruce instead.
Basswood is a bit denser than balsa, very fine grain and takes a stain very well. Most high quality HO structure kits use basswood.
Spruce is very hard but strong so only use spruce if strength is needed.
 
I would also advise strongly against 'saggy' softwoods. I would add cedar as a good choice if you can get it, especially for under-deck stringers, provided they aren't longer than about 8" and are properly supported at their ends, including mid-span pylons as needed. Use good glue at all joints, but also consider plates of styrene as webbing at the joints, cut to appropriate shape and size. You'll add immeasurably to the strength by adding a lot more glued surface. Later, if you wish, you can add tiny rivet heads to the styrene plates.
 



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