Bridge Designs

[brayden box]

What kind of design works the best?
thread for bridge http://www.scioly.org/phpBB3/viewtopic.php?f=209&t=7816

[brayden box]

Do you know a good design to use that's light?

[laidlawe18]

There is already a forum for Bridge Building. Please make new threads regarding bridge building in that forum.

[brayden box]

Sorry. I think I did it right, the thread I mean.

[bernard]

In response to your first post, I'll quote what I posted in another thread this year: http://www.scioly.org/phpBB3/viewtopic. ... 15#p280859

Has anyone found some successful ideas for the bridges?

If you're asking about design, there is no one best design. Some of the bridges that placed at nationals last year looked just like mine and others looked nothing like it. The best recommendation I can give is start with a design you like and think will do well (if you don't know what will do well, do some reading or look at pictures of bridges). Then test it, observe it as it is loaded and fails, then make more. Don't change a whole lot as you work towards a successful design or you might not know what's good. Students I've talked to who have done well in the event in the past have made many bridges.

Also, I've moved this topic to the Bridge Building forum.

[brayden box]

thanks for moving it. I forgot to put it in here.

[brayden box]

oh, and thanks for the advice. I did that, and I built a k-truss bridge. I held 42 pounds and wasn't even bowing! Only thing was, it weighed about 25 grams!

[SPP SciO]

Curious: has anyone ever built or seen a single-piece bridge? A student suggested starting with a single block of balsa and creating a real fancy looking bridge through subtraction..

On one hand, I think it's really interesting, and not impossible- drills, coping saws, hours of careful sanding ... On the other hand, it's a significant investment of time and money - Any thoughts before setting some kids loose on this project?

[UnprunedShrub]

Curious: has anyone ever built or seen a single-piece bridge? A student suggested starting with a single block of balsa and creating a real fancy looking bridge through subtraction..

On one hand, I think it's really interesting, and not impossible- drills, coping saws, hours of careful sanding ... On the other hand, it's a significant investment of time and money - Any thoughts before setting some kids loose on this project?

Wouldn't that kind of bridge be really weak? In a normal bridge, the grain is parallel to each piece, but in a single piece bridge the grain would be all messed up and could even be perpendicular to the member and would split easily in those locations. It would probably also waste a lot of wood and it would be really hard to make a bunch of these bridges. If you really want to go through this idea, I would suggest that you laser cut your bridge instead of trying to do it by hand.

[Less_Incidence]

Wouldn't that kind of bridge be really weak? In a normal bridge, the grain is parallel to each piece, but in a single piece bridge the grain would be all messed up and could even be perpendicular to the member and would split easily in those locations. It would probably also waste a lot of wood and it would be really hard to make a bunch of these bridges. If you really want to go through this idea, I would suggest that you laser cut your bridge instead of trying to do it by hand.

I would be inclined to agree with that statement. I can understand the reasoning with regard to the lack of glue joints, but given that a properly-made glue joint is tight-fitting and nearly always stronger than the wood itself, all that a one-piece bridge would do is create a structure that tends to split and crack along the grain direction. That's not really an ideal scenario for an SO bridge.