Bridge building in balsa

Discussion in 'N / Z Scale Model Trains' started by Gavin Miller, Dec 1, 2002.

  1. Gavin Miller

    Gavin Miller Member

    On my "turning" module (where the tracks disappear through the backdrop and turn 180 degrees) I have the problem of how to disguise the great hole in the backdrop.

    This photo shows what I mean:-

    Attached Files:

  2. Gavin Miller

    Gavin Miller Member

    I wanted to disguise the hole with a highway overpass.

    This would achieve two things. Allow road vehicle access to the industrial area on this module as well as cover the hole.

    I have started building a highway overpass using balsa wood abutments and bridge supports (these will be clad with other material when the job is finished).

    Here's the start:-

    Attached Files:

  3. Gavin Miller

    Gavin Miller Member

    This bridge has to be "purpose-built" for the location as it has to curve to mate with my curved backdrop.

    I needed a material I could curve sideways and downwards at the same time (to form the incline on one side).

    Balsa strips are ideal for this.

    This photo shows balsa strips bent and pinned in place while my bridge design comes together "on the fly". he heh

    Attached Files:

  4. Gavin Miller

    Gavin Miller Member

    Well, after 30 minutes, this is as far as I have got.

    But now I can at least see the "skeleton" of the desired final product. This is where balsa wood is just the most convenient modelling material. It is SO-O-O easy to work with (cut, glue, pin).

    You can see the aeromodellers' "T" pins holding things together in this photo:-

    (I'll post some more photos when I make some more progress)

    Attached Files:

  5. msh

    msh Member

    First the backdrop, now the balsa... Gavin, your work is quite fine and I personally thank you for your posts.
  6. Gavin Miller

    Gavin Miller Member

    Thanks msh.

    You might notice that my benchwork is also built out of balsa. This makes for super lightweight modules!!!

    Balsa is actually quite strong. That's why aeromodellers use it!

    Obviously if you king hit it or sit on your benchwork you will smash it, but how often do we sit on our benchwork?

    My thoughts are - why do we use such H-E-A-V-Y material to build our benchwork when the only loads we intend to place on it will be no heavier than an N-scale train? (I use light weight foam for scenery).

    As far as "above" the benchwork goes, well, my model bridge is never going to carry a load any greater than a few N-scale plastic vehicles so, even in balsa, it is "over-engineered" :)

    I will cut and lay a styrene plastic road base/shoulder across the top of the balsa and use plastic Arnold highway railings to complete the bridge.
  7. Tyson Rayles

    Tyson Rayles Active Member

    Great enginerrering job Gavin!
  8. Drew1125

    Drew1125 Active Member

    A great idea, & a great piece of "N-gineering"!:cool:
  9. n-scaler-dude

    n-scaler-dude Member

    Great looking bridge idea! It goes to show, especially to me, that nothing is set in stone when building a layout and things can be added/changed even if they were not originally planned for. Thanks for the photos.
  10. Ralph

    Ralph's for fun!

    That looks great! I think designing the bridge to follow the backdrop curve helps the eye accept the illusion that the scenery goes on well beyond the bridge. Neatly done!
  11. Gavin Miller

    Gavin Miller Member

    I have been "off-line" for about a week after a lightning strike took out my cable modem but bridge building has continued.

    I have constructed a bridge pier using balsa off-cuts and Plastruct styrene tube

    Attached Files:

  12. Gavin Miller

    Gavin Miller Member

    A quick test fit inder the bridge deck.

    I have carved the block of balsa in the foreground to a landscape profile and painted it to match the rest of the fascia.

    I have also realigned the road to a continuous curve through and off the bridge.

    Attached Files:

  13. davidstrains

    davidstrains Active Member

    very neat idea and work so far. Looking for the deck to be put down and concrete poured.:) :) :)
  14. Gavin Miller

    Gavin Miller Member

    Some of the concrete has been "poured".

    I used some mid-grey "German Board" (available from art stores) to cover the grain of the balsa and represent the "concrete" bridge abutments. I drew lines with a 2B pencil (then smudged a little with my finger) to represent the "pour" lines in the concrete.

    Attached Files:

  15. sumpter250

    sumpter250 multiscale modelbuilder

    That looks good to me! Nicely done!
  16. Vic

    Vic Active Member

    Hi Gavin, I've been following your posts and have been intrigued with the layout construction from balsa wood. A lot of train modelers sell balsa short as a construction medium. As you have done, properly used it has great strength and you can do things with it that you cannot otherwise do with harder woods.

    Unfortunately balsa has become rather expensive here in the US as most of the balsa sold here comes from South America (mainly Brazil) and the depleation of the forests and poor economys there have driven the price up. (I love to hear my airplane modeling buddies gripe!!:D :D )

    I was just curious as to where the balsa obtainable in AS. comes from....the Phillipines? or is it native to your part of the world?
  17. Gavin Miller

    Gavin Miller Member


    I am not sure where we get it from (apart from the hobby shop haha). I presume Indonesia or the Phillipines. It is quite expensive here too if you want to complete a project using LOTS of it. But for my little bridge project, the 60 cent strips didn't break the bank!

    I buy styrene sheet (for my roads, etc) from a plastics manufacturer by the metre - much cheaper than those little Evergreen sheets in the hobby store.

    In this photo I have laid my bridge deck down onto a sheet of styrene so I can trace the curve of the bridge onto the plastic.

    (You will note the four strips of balsa which form the bridge deck have been held in the correct curve by a batton of balsa temporarily pinned across them)

    Next task will be to cut out the road section from the styrene sheet and paint it grey.

    Attached Files:

  18. Vic

    Vic Active Member

    Hi Gavin and thanks for the information. Sometimes my curiosity "gets up" over the strangest things.

    You might already know this...but if you wet balsa strips with Windex ( or any other amonia based window cleaner) they will bend even further then if dry. When they dry back out they will pretty much hold the curve bent into them.
  19. Gavin Miller

    Gavin Miller Member

    Hmmm ... no, I didn't know that, but this is sure a good project to try it out!

    While my bridge "girders" are off the layout is a good time to give them a spray.

    Thanks for the info.

    Out with the Windex ...
  20. Vic

    Vic Active Member

    Yep, that's an old airplane building trick. Sometimes you have to bend balsa further than nature intended it too!!!:D :D

Share This Page