May 18, 2015

Building Bridges on the 3D Printer

Bridge building has been a pretty common topic used in school science and physics lessons over the years - probably because it is a fun way to explore force and weight distribution, even math and material strength. I thought it would be fun to create a 3D Model of a suspension bridge to give science teachers a starting point to combine 3D Printing with these lessons. I also think this world is in desperate need of many more bridge builders, so kids should learn how to build an actual bridge as early in life as possible! (yes, I'm kidding).

The 3D Model - Multi-part again

Given my obsession with multi-part objects, I figured I should also try that here. Actually - the motivation is more of a practical goal of "getting complex things to print". Most 3D Printers still cannot print everything you design so easily - they specifically have issues with something called (ironically) "bridging" - where there is some part of an object which has not supporting material to the ground. In the bridge project - no surprise - there would be a long span which has no support from the bottom. So - printing the bridge in parts (which is actually how real bridges are made, right?) seemed logical and practical.

The Design

I set out to design a suspension bridge which was visually modeled after the Verrazano Narrows bridge, in Brooklyn, NY. This bridge opened in 1964, and has some really interesting facts around it's construction and use (including being the starting point for the NYC Marathon). But I didn't set out to mimic it's relative dimensions - I just estimated by eye what would look good. I decided to construct it in 3 parts - the tall stanchions, the short stanchions and the cables. You can see how some of the parts look on the 3D Printer bed to get a better sense of what the parts are.

The Results

The snap together parts don't work all that well yet - but this first version is just a prototype of something I might make better over time. The scale of it - 2 spans measuring approx 8 inches wide and 3 inches tall - made it difficult to make sturdy. But this first version at least looks pretty good when put together. I will definitely glue it to make it stronger.

Let me know in the comments if you have ideas on how to use this in a real school lesson or how you think I could change the model to make it more useful or interesting. I've got plenty of time to do stuff like that (uh... not really). I'll post this model soon in a place where anyone can download it.


  1. Very interesting. Something I've wanted to do for a long time as part of my long-running Physics Balsa Bridge Building Contest (

  2. I'm interested in printing this. Is the file available? Thanks!

  3. That's what we make in Poland! Check it out! : )