<instructions>Your goal is to analyze the following comment and estimate how highly it will be upvoted by the Hacker News community.</instructions><comment><author>NortySpock</author><text>To steelman the argument, maybe they meant &amp;quot;the monitoring system is good enough at catching defects that if none are reported, the engine will probably pass an all-up hotfire test of the engine&amp;quot;.&lt;p&gt;Of course you could do a water or air-pressure leak test on the plumbing pretty easily, and you would likely do that on the first 30 engines...&lt;p&gt;But if you have confidence in your build process, maybe the juice isn&amp;#x27;t worth the squeeze on (say) a direct contact ultrasound void check on every square millimeter of the part.&lt;p&gt;It&amp;#x27;s all about &amp;quot;how expensive is it to run the test&amp;quot; vs &amp;quot;what is the likelihood the test catches an issue&amp;quot; vs &amp;quot;what&amp;#x27;s the cost of failing while everyone is watching?&amp;quot;&lt;p&gt;Same reason SpaceX went from dry-dress-rehersals to wet-dress-rehearsals to separate-static-fire-before-launch to hold-down-for-three-seconds-before-launch... The hold-down -before-launch is an integration test that covers everything the previous tests do, so eventually you can start removing redundant tests.</text><parent_chain><item><author>Etheryte</author><text>&amp;gt; The machine also automatically outputs a report that details any deviations during printing, removing the need for postfabrication qualification.&lt;p&gt;Anyone who&amp;#x27;s previously worked with 3D printing knows that this simply does not pass any kind of a sniff test. Both preventing and detecting internal defects is one of the, if not the hardest problem in 3D printing. There are many large companies trying to find ways to reliably solve just this problem alone. Saying that this method doesn&amp;#x27;t require any checks after production is simply false.</text></item></parent_chain></comment><story><title>Indian startup 3D prints rocket engine in 72 hours</title><url>https://spectrum.ieee.org/3d-printed-rocket</url></story>
<instructions>Your goal is to analyze the following comment and estimate how highly it will be upvoted by the Hacker News community.</instructions><comment><author>surfingdino</author><text>I too am doubtful. The market is littered with failed 3d printed products, all failed because the designers know nothing about real-life product design or because their deigns are too brittle or melt too easily in heat.</text><parent_chain><item><author>Etheryte</author><text>&amp;gt; The machine also automatically outputs a report that details any deviations during printing, removing the need for postfabrication qualification.&lt;p&gt;Anyone who&amp;#x27;s previously worked with 3D printing knows that this simply does not pass any kind of a sniff test. Both preventing and detecting internal defects is one of the, if not the hardest problem in 3D printing. There are many large companies trying to find ways to reliably solve just this problem alone. Saying that this method doesn&amp;#x27;t require any checks after production is simply false.</text></item></parent_chain></comment><story><title>Indian startup 3D prints rocket engine in 72 hours</title><url>https://spectrum.ieee.org/3d-printed-rocket</url></story>