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Comment by mikevm | Hacker News Reader

I was wondering, are 3D-printed objects more fragile compared to similar objects being created with classical methods? For example, some metallic parts, or say, the foundations of a house.

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The answer is 'it depends'. There are a variety of processes and materials that are called 3D printing. For plastic fused deposition modeling (like the Makerbot), objects can be comparable to say, injection molded parts, which is a more common plastic production method. For metal, selective laser sintering is the most common method, and the parts it produces have different (and probably inferior in most cases) properties than cast/forged/machined parts. There's way too much variety on either side of the coin to say which is more fragile.

I know that reinforced concrete is often used in construction, so I figured that printing a huge house would make it more fragile, say, during an earthquake.

From what I've anecdotally heard, SLS parts are actually stronger than a cast part of the same shape.

Makerbot parts can be considerably weaker than injection molded parts because of issues with delamination between layers.

NASA have put a 3d printed exhaust port on a rocket engine and test fired it successfully. - http://www.nasa.gov/exploration/systems/sls/j2x/3d_print.htm...

Besides, as long as you know what you are doing it is just another material to select from and you just calculate critical dimensions based on measured properties.

Solid Concepts built a 1911 pistol with a 3D printer. The barrel has to withstand 23,000 psi pressure (to comply with SAAMI specs), so it's a stressed part, for sure.

http://www.cnn.com/2013/11/08/tech/innovation/3d-printed-met...

No. 3D printers enable feats of engineering that would be impossible without their availability.

You don't need to make the plastic part in two pieces so that a screw can fit into one of them, for example.

House foundations are 3d printed in a sense... The dots of plastic are just larger and take longer to dry ;)

You're not addressing the strength or fragility of the artifacts though.

Some 3D printed objects are actually superior for strength, for example plastic with a honeycomb interior can have an amazing strength/weight/cost.

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