Recently, the cost and quality of 3D printing has become reasonable and CAD software has become easier to use, allowing anyone interested and motivated to design and print 3D objects.
I was surprised when I saw a functional version of Theo Jansen's Strandbeest a few months ago on Shapeways, because I thought all 3d prints were fragile and would crumble if you tried to make something with that many moving parts. I wanted to try to make one myself, so I downloaded the student version of Autodesk Inventor during winter break and got to work on what would become my first 3D Print.
This instructable details the steps I took to make one of Theo Jansen's Strandbeest using a 3d printer. The finished design was printed fully assembled. The full scale .stl file can be downloaded here, the .77 scale here, and the .66 scale here.
Step 1: Sketching the Parts
Using the Theo Jansen's proportions, make an outline of each of the 8 parts using millimeter scale.
I used a minimum width of 2mm in the outlines, and a 7mm outer diameter for where the hinges will go.
If you are using Autodesk Inventor, John Helfen (Autodesk Student Expert Program Manager) does a great job of demonstrating how to start sketching in his videos here.
Step 2: Modeling the Parts
Be sure to make hinges with clearances that will work with your 3d printer/material. I left a .5mm clearance around all moving parts.
I used a fillet on the inside contact area of the hinge so that if the parts did fuse, only a small part of the pieces would stick together and could be worked free.
John Helfen's videos on modeling parts here.
I've included the finished parts below.
Step 3: Assemble the Parts Into a Sub-assembly
Be sure that there is at least .5mm clearance between all moving parts.
Here's a video of the process.
Also, John Helfen's videos on assembling parts are available here.
Step 4: Mirror the Sub-assembly to Finish the Strandbeest
Align the blue parts in the third picture so that they are at a 60 degree offset from each other.
Now mirror the entire structure to get the final model.
Step 5: Print
Export an .stl file from your 3d software. I scaled my .stl down to 77% scale when exporting to print because full scale would have cost $116 to print, I knew I was running the risk of having the parts fuse together because all of my clearances were below .5mm but I took the chance because 77% scale only cost $54 to print.
Some of the hinges were fused when I received the print so I carefully worked each of them until they began to move. The hinges eventually became smooth with use. I printed a test sub-assembly at 2/3 scale and the joints also functioned well after use, at this scale, a full print would cost $35.