May 28, 2012

Making more than meets the eye

I've been looking into 3D printing a lot lately, particularly with a slant toward toys. You know, for my kids. Growing up, I was always frustrated when a small but important piece on a toy would break, and render the whole thing useless. I imagine this will be a problem with my kids' toys as well. I wanted to see if 3D printing can help solve the issue.

Coincidentally, my parents have been cleaning out their house recently, and dropped off a bag of my old toys. Inside was this broken Transformer, Perceptor.

He's a robot that transforms into a microscope. He fights evil with his ability to see really small things. Maybe the Decepticons were getting into germ warfare or something.

Anyway, his lens/cannon broke off pretty early on. The holder piece that broke couldn't really be taped or glued back together, because it had a bit of springiness that kept it in place, and glue just wasn't up to the task.


So, 25 years later, I tried to fix him with a new 3D printed piece.

I measured the remnant broken piece. I only had ⅔rds of it, but luckily, it seemed symmetrical. It's a pretty small piece, so I used a set of calipers, which is really just a ruler for lazy, indecisive people.

Using TinkerCad (a free web-based CAD program), I reconstructed the piece in 3D. This took some learning, and TinkerCad doesn't seem make it particularly easy to get exact dimensions, but I was pretty happy with the result. The final dimensions of the drawing were within a few tenths of millimeters of my measurements. It took hours, but I think I could do my next one in under an hour.


Then I ordered the piece from Shapeways, an online 3D printing service. It was only $3, which is nice, though shipping brought it to $10. I had to get this right on the first try, as this would be expensive if kept ordering iterations. What I did instead, though, was impulsively place the order when I was just planning on pricing out the piece, and I didn't really even double-check my design. So this was likely $10 down the drain.

The piece arrived a week or so later, and came out pretty well.


My measurements were about right, though I pushed the boundaries of Shapeway's printing abilities, so where there should have been a narrow tubular hole was a mostly-filled-in depression. I corrected that easily enough by gently slamming a metal pin through it.


The bigger problem was just an incorrect assumption I made early on: The original piece was not symmetrical after all. When I tried to attach the printed piece to the robot, I found that the one of the holes was much larger than the one on the other side, so my new piece fit very loosely.

To compensate for this, I used ShapeLock, a moldable plastic I've had sitting in my closet for a few years. After warming it up, I was able to wrap it around one of the legs of my piece, and mold it into a shape that fits in the larger hole.



So now he's all fixed up, and the kids are having fun with him.

Bottom line, though: 3D printing is really not an economical way to fix a toy, given that the cheapest home 3D-printer is over $500, and a replacement for most toys would probably be under $20. (an eBay version of this same Transformer is $30). Nor is it faster: even if you design and print at home, it still takes longer than a trip to Toys 'R Us.

But it can keep a toy out of the landfill, and make me proud of my fix-it abilities. And of course, 3D printing has applications other than just fixing toys. Like making robots. You know, for my kids.

Posted by Kevin at May 28, 2012 09:41 PM
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