Hi, Sean,
That thought had occurred, but I hardly know enough about molds and
casting to comment.
As with any technology, it's important to know:
1. What it's good for, and
2. What's it's not good for [yet].
It will be interesting to see what develops in 3D machinery,
techniques, and applicable materials over the next few years. I'm
hoping that non-metallic parts become superior to metallic for more
applications (both interior and exterior) because of corrosion
considerations. If durability, reliability, and fabrication can come
together, it would be great.
Jim
In a message dated 2/13/2012 1:19:17 P.M. Central Standard Time,
cast55@telus.net writes:
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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