Fwd: [AR] freeform metal fabrication
Bryan Bishop
From: Trent Waddington <trent.wa...@gmail.com>
Date: Sun, Feb 14, 2010 at 7:41 PM
Subject: [AR] freeform metal fabrication
To: arocket List <aro...@exrocketry.net>
I was looking at some NASA technology called Electron Beam Freeform
Fabrication (EBF3),
http://www.aeronautics.nasa.gov/electron_beam.htm
http://www.youtube.com/watch?v=WrWHwHuWrzk
To summarize, they're doing electron beam welding on a movable
platform and making stuff out of the wire. And, being NASA, they
wanna do this in space.. yeah.
My initial thought was "ohhh, it's a MIG on a RepRap!"
That's not an accurate description, as they're doing electron beam
welding in a vacuum, not arc welding in a shield gas, but you get the
idea. Must be nice to have room sized vacuum chambers.
But I wonder.. if you did use arc, and a helium tent, it seems all
very off-the-shelf and not expensive at all.
No surprise, the example part on the first link, and in the video, are
rocket nozzles.
Trent
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Bryan Bishop
From: Ben Brockert <wik...@gmail.com>
Date: Sun, Feb 14, 2010 at 10:14 PM
Subject: Re: [AR] freeform metal fabrication
To: Trent Waddington <trent.wa...@gmail.com>
Cc: arocket List <aro...@exrocketry.net>
A friend of a friend makes small art sculptures entirely out of fill
rod, using an oxy-acetylene torch. Basically the same idea, and you
could do it in microgravity too.
Their solution is kind of impressive in how bad the resolution is. It
looked like it wasn't sensing what it was doing, either, see the
divots in the circle. Some FDM machines increase their resolution and
fix issues like that by being blind but cutting off half thickness of
every layer put down, so the base is always where the machine thinks
it is.
Seems like an SLS machine in a weak centrifuge would give vastly
better results, if you really need something that works in
microgravity. Building really large structures with either would take
a very long time.
I used to work with a stud welder, used for sticking threaded studs
onto sheet steel. A similar system could work well for making large
structures; you'd start with a bunch of rods or tubes, and stick them
to each other to create beams, cages, etc.
Ben