SpaceX’s Elon Musk executed an “Ask Me Anything” session this week on Reddit, and revealed something interesting about their 3D printing use.
The session on Reddit proved very popular and is still online for you to review in detail. It is long, however, with many thousands of words involved. Musk participated in the session to answer questions about his proposed “BFR” system that could revolutionize space travel by bringing the costs down to current airline fare levels with similar reliability.
Of course such a dramatic proposal has generated many questions, and that’s what the public asked during the session. One question, however, gathered my interest as it involved 3D printing. The question asked was:
The unprecedentedly high degree of integration between Raptor engine components has created speculation on /r/spacex to what extent the Raptor might be metal- 3D printed. SpaceX's SuperDraco engines are 100% 3D printed, so SpaceX has extensive experience with using 3D printing to build smaller scale rocket engines.
Do the benefits of 3D printing transfer to the Raptor scale as well, for example is it practical to 3D print the Raptor's main combustion chamber, or is casting+machining still the better technique?
Elon Musk replied briefly:
Some parts of Raptor will be printed, but most of it will be machined forgings. We developed a new metal alloy for the oxygen pump that has both high strength at temperature and won't burn. Pretty much anything will burn in high pressure, hot, almost pure oxygen.
There were quite a few responses focused on the new metal alloy, as such a material could be used in countless other applications - including 3D printing, perhaps.
But the message I received was a bit different.
SpaceX has a reputation for doing very advanced projects using similarly advanced tools. As such there was a bit of a feeling that 3D printing would “obviously” form a large part of their build process.
But apparently it isn’t.
And there’s a strong message here: 3D printing is just a tool, not an end unto itself. A project must select the most appropriate tool for each task, and sometimes that is 3D printing, and sometimes (or often) it is not.
Musk correctly suggests that SpaceX is “choosing wisely” when developing the BFR. Traditional approaches may be “boring” or “old”, but they are still very effective and the right choice in many situations.
Let the applications find the solutions, not the solutions find the applications.