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3D Printed Support: Armed and Dangerous

3D printers, in tandem with slicing software, have grown ever more sophisticated as the additive manufacturing industry has evolved. A virtuous cycle emerged, where advances in one led to advances in the other.


But there’s a dark side to this increasing sophistication: we’ve come to rely ever more on 3D printed support material.



If the print doesn't fail, support removal will

Whether your printed supports have literally drawn blood during removal, or you’ve been fortunate enough to never touch the stuff, we submit for your consideration a list of pros and cons.



Our conclusion is that support material should be avoided.


The best way to do that is by using a 3D-printing-first approach.


To that end, here are five 3D-printing-first techniques that will enable you to design support-free parts.


Rule 1

Choose orientation first


Design the part for a specific print orientation.



The bottom of the finished part does not have to be the bottom of the print. Rotating the part by 180° may obviate support. Alternatively, rotation of ~45° may also facilitate clean printing.


Rule 2

Avoid steep overhangs


When extruding along an overhang, new plastic has little support below to keep it in place. As a result, overhangs can sag or fail outright.


Overhangs can often be avoided, if not by simply decreasing the angle in CAD, then by using horizontal bridges instead of angled faces. Horizontal bridges tend to print more cleanly.




Rule 3

Use smart overhangs


If an overhang cannot be avoided, use these techniques to facilitate clean printing.


Support the angled face with vertical masses on either end. The face then becomes a bridge rather than a cantilevered overhang.


If there's no flexibility regarding part geometry, the last resort - albeit a powerful one - is your slicer. Fine-tuned slicer settings can be the difference between a high resolution print and spaghetti. Here are some of the most important adjustments.


Slicer settings that prevent sag

While optimizing slicer settings for overhangs does increase print time, it's a tradeoff worth making if you value quality over speed.


Rule 4

Divide the part


Some parts can be split into sections, each of which is optimized for a specific print orientation. However, the obvious solution - splitting the part in CAD and gluing together the printed pieces - often leads to glue scarring and misalignment. Instead, we encourage you to consider these joining methods.


Snaps

Pros: instant joining of parts; no glue needed

Cons: probably not strong; potential for rattling


Hexagonal pegs

Pros: sections cannot rotate relative to each other; high strength

Cons: requires glue; requires precise clearances


NB: consider adding a small chamfer along the base perimeter (footprint) of your parts. This counteracts the tendency of base layers to mushroom out during printing, ensuring that all pieces are flush when interlocking.


Rule 5

Design smart supports


Sadly, the above techniques will at times not suffice to get around the need for support. Should that be the case, rather than surrendering your fate to the whim of your slicer, build the part to rely on a smart support of your own design.


Smart support checklist:

  1. Identify the location where a support is unavoidable

  2. Design this place to rely on a simple support of your choosing, such as a pillar or thin wall

  3. Give your chosen support the biggest possible bed footprint (for adhesion)

  4. Give it the smallest possible intersection with the part (for ease of removal)

  5. Place it near the outermost perimeter, or inflection points, of the part

  6. Consider adding a handle to facilitate removal



Try to keep in mind these techniques as you begin designing your part. While it may be tempting to simply CAD the simplest solution and outsource the heavy lifting to your slicer’s support algorithm, we believe that, in the end, a 3D-printing-first approach will yield better results.


Printing without support yields better surface quality, eliminates post-processing effort, reduces print time, and, crucially, improves printability for others in the maker community.


Happy CADing!