Extruding Aluminum Shapes

[Keith Mc]

Rick-o-matic (Rick Chownyk) has shown that it is very possible
and easy to do aluminum castings at a hobby level.

But I'm curious to know if anyone here has ever attempted,
know of people, or seen links to DIY aluminum EXTRUSIONS?

In addition to basic 8020/Bosch/IPS structural extrusions, I've been
seeing LOTS of "sliced extrusion" products out there these days.
Ex: the Servo City "Servo Blocks", and servo mounts:
... http://servocity.com/html/vertical_aluminum_mount.html
... http://www.servocity.com/html/standard_hitec_servoblocks.html

You basically start with a small custom profile shape extrusion,
drill and tap it as desired along its length, slice it apart like a
loaf of bread, and deburr the pieces (the easiest is probably
doing an abrasive tumble polish, like polishing rocks).
Given the right extrusion shape, it makes creating tons of
identical parts very easy.

Now I doubt this would be worth attempting this for 1" or larger
structural extrusions. The scale and required melt volume quickly
exceeds hobby levels.
But this may not hold true for SMALL extrusions, like hobby robot parts.

So I'm curious to know if it would be possible to make a bit of
custom extrusion for SMALL scale items, like the above servo mounts?
I think this could be a huge boon to running a bunch of "cast"
parts for robotics, that require lots and lots of copies of the same
part. Ex: modular robots, tentacles, snakes, spines, millipedes, etc.

Sure, you can always CNC the end of a butter stick block of aluminum,
slice it off, recycle melt all of your swarf, cast them back into more
raw blocks, and repeat. But that's an awfully high energy cost every
time you recast the swarf. IMO extruding a short stick of the
desired shape ONCE from a single initial cast melt of scrap aluminum,
then slicing it up like a loaf of bread to quickly make your parts
would be a lot more energy efficient.

But ordering custom extrusions entail high setup charges, so it's
not worth it for hobby purposes. You'd have to find a way to make
money on it, to attempt it. (IOW, this is not home fab tech, YET.)

So... What would it take, to make a simple device to produce
a short length of a custom extrusion profile, supplied with melted
aluminum from a perhaps a slightly scaled up Rick-o-matic
aluminum melt forge?

I'm imagining something along the lines of a steel Play-Doh Fun Factory.
You CNC a replaceable die, and it is driven by a gravity pressure head
and/or assisted via pressure from a hydraulic bottle jack.

But, heating the extruder assembly and holding the metal right
at that magic plastic point to do a proper extrusion (without running,
sagging, or locking up the gadget) may NOT be a simple thing to do.
In fact, it might even require more energy to make a little stick
of something than simply doing the above "CNC & recycle the
swarf" process.

Any thoughts? Has anyone done this already?

Would such a DIY gadget even be reasonable to ATTEMPT?
Or, does the energy economy and complexity of doing this in
small scale advise against it?

Would having "free energy" change the situation? (eg using a solar dish
furnace to melt the aluminum, and/or preheat the extrusion widget).

If aluminum is still too tough for hobbyists, would attempting shaped
extrusions in a THERMOPLASTIC (like ABS) be achievable?

- Keith Mc.

[Andrew Meyer]

On Thu, May 31, 2012 at 11:26 AM, Keith Mc <ac...@provide.net> wrote:
> If aluminum is still too tough for hobbyists, would attempting shaped
> extrusions in a THERMOPLASTIC (like ABS) be achievable?

Given the current incredible difficulty in making the simplest
thermoplastic extruder (AKA filament recycler) indicated by the
current $40000 prize for such offered up by Inventables, I suspect
that aluminum is above the hobbyist reach at the moment.

Inventables prize offer:
http://inventables.blogspot.com/2012/05/40k-desktop-factory-competition-to-make.html

--
Andrew G. Meyer
agm...@gmail.com
"Both optimists and pessimists contribute to our society. The optimist
invents the airplane and the pessimist the parachute."--Gil Stern

[Stephen Hermann]

temp above 900f and verry high (8000psi) or more is beyond me.

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