I Needed A Simple Design to Test Some New 3D Printed Joints so I Made a Square   5 comments


After the most recent Paul Kaiju show at FOE, I got a chance to stand outside in the cold of frosty Northampton and talk shop with Sanjeev Teh Jerk, master of all things 3D design.  While I have been going headlong into home-grown ABS printing, Sanjeev has been working on some face-meltingly cool multimedia affairs for production through Shapeways.  Production method aside, we are both always looking to existing toys for inspiration.  Sanjeev mentioned to me how he had recently cracked open a vintage Gokin and found a joint design that we both were pretty sure would work in 3D printed ABS.  We talked, froze our asses off, and then I went home, and the gears were in motion.


After mulling over the idea for a couple of days, I decided to whip up some tests.  I fired up Pro/Engineer and the parts started flowing.  It did not take long to realize this was totally going to work.


The hexagonal peg fits into a matching hole.  The female part is printed lying flat on the printer bed, so the grain of the plastic works with the design to form a springy socket.  ABS is slightly flexible, so the socket flexes as the peg is rotated, making a gloriously clicky detented joint!


ThreeA’s Square^2 is an awesome little design that I have a whole bunch of and love.  It is also made from some very simple shapes and made for the perfect test bed for the detent joints.  Before we go any further, let me make it clear that my imitation Square^2 will never be for sale or distribution in any way and is not meant to infringe on 3A’s design.  It is simply a simple design that I had on hand for inspiration while testing out some ideas.  Call it a tribute.


With that said, let’s talk about the design.  I made the knee joint as a wraparound joint that the peg slides through.  The hip is a fixed peg attached to the pelvis with the rotation in the leg part.


An octagonal peg allows for very positive detents, but that also means it has very few clicks of motion.  I am printing some experiments now using twelve and sixteen sided pegs, trying to find the balance between rugged clickyness and granularity of motion.


The Square^2 does not need to be super posable, though, so after adding a couple of aesthetic caps that also keep the pegs from sliding out, my new little buddy was ready to roll.

detent-square1-03I made the feet a little bigger than on the official toy to help with balance, and came up with a couple little details to help differentiate my imitation Square^2.  For a quick afternoon design to test the joints out, he works perfectly.

detent-square1-02He even has a little butt vent!

Now that I know the joints work, I can start working them into new Prometheus Rising Heavy Industries designs…

More to come!

5 responses to “I Needed A Simple Design to Test Some New 3D Printed Joints so I Made a Square

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  1. Thoroughly enjoying your posts on 3D Printing experiments. Ingenious ‘butt vent’ too!

  2. I’d love to have this model as a starting point for a Square – would you share it with a like-minded 3D Printing nerd?
    Thanks – great work!!

  3. Pingback: PRHI 3D Printed ‘Box’ Mk I and Mk II 1/6 Scale Printable Files | Prometheus Rising Studios

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