3d Printing: The New Hotness

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I was first exposed to stereolithography (SLA) back in 2008. This was before the term 3d printing was in common use. It was on a job involving the recreation of a full-scale Terminator robot for the Sarah Connor Chronicles television series. Certainly, a lot of man hours were saved in sculpting but the parts were of a pretty low resolution and required extensive cleanup and body shopping (sanding and bondo). The resin was also very brittle. It was interesting but I didn't think too much of it at the time.

A couple of years later, I started hearing rumors about 3d printers. “Oh great,” I thought, “more brittle plastic parts eating countless hours of bondo and sanding time.” It was a  different technology, however, similar to a computer controlled hot glue gun, called fused deposition modeling (FDM). Promising, but still not ready for primetime.

Then in 2012, Make Magazine came out with a special edition featuring 3d printer reviews. In 2013, based upon these reviews, I bought a Type A Series 1 3d printer. Then in 2014, I actually pulled it out of its box, taught myself to use a CAD program and started printing. Can you say no longer under warranty?

Woody the 3d printer

Woody the 3d printer

Old School Machining: a Few Thoughts

 

Machining has been the mainstay of animatronics fabrication for a long time. Aluminum, brass, and steel were some of the materials of choice in the creation of animatronic mechanisms, and for many applications still are. However the machining process can be labor-intensive and milling machines and lathes are big, heavy, and pricey. The introduction of 3d printing technology has changed the situation.

Pros and Cons of 3d Printing (FDM):

 

Pros:

  • Robot time versus man hours: Complexity not an issue. An intricate part and a simple part of the same size require the same amount of time to make.

  • Only requires occasional supervision.

  • Rapid prototyping/quick iterations: different ideas can be tried out in rapid succession.

  • The equipment is more affordable, accessible, and mobile than metal working equipment.

  • A wide variety of materials are available, each with their own potential specific applications.

  • Makes for a lighter finished product.



Cons:

  • Plastic is weaker than metal.

  • Plastic is less stiff than metal.

  • The layers of weakness inherent in the printing process.

  • Parts need a flat side to attach to the print bed.

  • Plastics generally don't machine and thread well.

  • The equipment can be finicky and lacks the longevity and durability of milling machines and lathes.

  • Susceptibility to failures:

  1. wrong settings

  2. clogs resulting from contaminated filaments ( dust, moisture, etc.)

  3. sensitivity to variations in temperature

  4. and don't bump the machine when it's working, for God’s sake!

  • Does not scale: there no advantages to making a run of multiples. Its all about the prototypes.

  • Maintenance of equipment. You will become an expert in troubleshooting these things if you stick with it for any length of time. Hope you enjoy tinkering and talking to tech support. You will be doing a lot of it.

Materials For 3d Printing:

Here is a run down of the materials I have used in my 3d printing and what I can say about them.

ABS

  • Body shops great (bondo, sanding, filing)

  • Gluing and welding excellent

  • Prone to warping during printing

  • Cheap

  • Needs a heated bed to work best


PLA

  • Biodegradability not a selling point when going for durability and longevity

  • Texture is glossy and waxy. Not conducive to body shopping

  • Not as prone to warpage as ABS

  • Does not need a heated bed. Probably it's best feature


Carbon Fiber PLA

  • Save the wear and tear on your machine and don't use it

  • Has improved stiffness characteristics

  • I like the matte black carbon fiber color


Ninjaflex

  • Tough

  • Very flexible

  • Great for special applications:

  1. small joints

  2. user interface pads ( hand grips, wrist pads, headbands, etc)


Taulman Alloy 910

Has all the desirable qualities of nylon but it is easier to work with.

  • Tough

  • Somewhat flexible

  • Holds a memory/ snaps back into shape when flexed

  • Slick surface = less friction (makes a good bearing surface)

  • Threads well

  • Good wear characteristics


Polycarbonate

  • Strong

  • Machines and threads well

  • Slightly gummy texture does not body shop as well as ABS

  • Needs high temperatures and a heated bed to print

  • Stinky and fumey during the printing process

Book Recommendations:

 

Functional Design for 3d printing by Clifford Smyth

 

The Zombie Apocalypse Guide to 3d printing  by Clifford Smyth

 

These books are full of great information and practical tips for anyone interested 3d printing functional components for animatronics. The the first book is concerned primarily with aspects of the design, as you may have figured out from the title. The Zombie Apocalypse book is more about getting optimal results from your 3d printer. There is some overlap between the two books but both are worth having. The author also maintains they very informative blog at Threedsy.com .

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