One thing that nobody has mentioned yet is to look beyond using the
available plastic materials to simply produce finished parts. 3D
printed plastic solids actually make ideal positive molds for
sand-cast aluminum or steel parts, and can save you a significant
amount of money on castings when you avoid having to involve a
skilled pattern maker - particularly for complicated geometries,
compound curves, etc. Designing for casting is not difficult - just
a few key considerations such as adding draft (slight taper to
facilitate removal from mold), avoiding cooling / shrinkage problems
by avoiding abrupt thermal mass changes in geometry, and maintaining
reasonable minimum wall thicknesses. After casting, you can either
finish mechanically, or as a colleague of mine does regularly, trim
the worst by hand, sandblast to even out the rest, then spray with
polyurethane or "tool dip".
As far as suggestions for finished plastic 3D printed parts, I might
look at things in non-critical service, such as fairings, aesthetic
trims, console bezels, etc.
-Sean
On 2012-02-12 18:10, JimToddPsub@aol.com wrote:
Hi, Alec,
I checked Wikipedia for the different types of 3D printers
and learned more than I have the capacity to absorb at this
point. ABS might be a good alternative to metal for actuator
housings. I'm sure I'll be considering the question for a
number of components.
By the way, last week I went through your Snoopy250 and
Snoopy Updates postings on the Psubs website. Picked up some
good ideas and suggestions. Thanks for taking the time to
take all those pics and post your comments.
Take care,
Jim
Hi Jim,
There are a variety of materials available, but the
two most common are ABS and PLA. For kids toys and such
I'm using PLA because it's biodegradable. If you're
going to be melting plastic inside the house for hours
on end, it strikes me as preferable to use something
that is derived from plants and doesn't smell bad. For
sub parts, though, I'd use ABS because it's stronger. I
don't have specs handy, but it's the same material Legos
are made of, so should be relatively tough.
There is no manufacturer for the machine, I made it
from parts that I collected from a variety of sources -
mainly eBay. As for accuracy, it's highly variable and
depends, from what I've seen, much more on the
experience of the person calibrating than the inherent
capabilities of the machine. I'm a rank beginner, so I
don't expect to make anything superb, but the quality
I'm getting at this point is sufficient that I would not
feel bad putting parts on the sub, presentation-wise.
I'd say it's functional and not embarrasing, but
certainly not yet the finish you'd expect from a mass
produced, molded item.
If you want to read a little about this stuff, do an
online search for "reprap", which is a collaborative,
online project to develop these machines, or for "Prusa
Mendel", which is the particular sort of printer I
built, a model developed by the Reprap project. More
generally, common terms for this topic are "additive
manufacturing" and "desktop manufacturing".
Best,
Hi, Alec,
I don't have any need at the moment, however
I'd like to hear more about the material's
properties and characteristics such as torsion
strength, etc. Are there different formulations
of plastic material for use with your 3D printer
at this time?
How precisely can it produce an item? Is
there general info available online at the
manufacturer's website?
Thanks for the offer. I'll need to take a
closer look at 3D printing in general versus
machine work when I get to that point.
Best regards,
Jim T.
Hi everyone,
I’d
mentioned a few weeks ago I was
working on a 3D
printer. It
is now
calibrated and working
really nicely. I have
to say, it’s a
neat concept to just hit a
button and watch things
materialize without
further intervention.
Now the
question is what to print.
There are
two main limitations:
- Parts must fit on a
build area measuring 6.75” x
6.75”
and 4”
tall, or they
have to be assembled from parts that
fit into that
space.
- Overhangs
have to be gradual. To
illustrate, consider printing a model
of a
house. You
would
have to print the
roof as a separate part and then
attach it to the walls, otherwise
when the nozzle reached the height of
the eaves it could not print them
because they would
be unsupported.
I know there are some
terrific CAD artists in the house, and
I’d like
to invite you to undertake the
design of printable sub
components on an “open
source” basis. I’d be
quite happy to print
those parts
for just the cost of the plastic, if we
can come up with some common sub
components. We could make
parts as simple as handles
for Kittredge style hatch dogs, or maybe attempt
an UW
light or a scrubber. Maybe
we can even start a repository for the
files.
Any takers?
Thanks,
Alec
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