Paul, The Stereo Lithography system isn't really as you describe. The
system you are describing is
a layer buildup rapid prototyping system. A simpler and more efficient
system than Stereo Lyth. In
the true Stereo system the part is built in a vat. The process uses two
lasers, (hence stereo) and
the point at which the lasers impinge heats a special thermoplastic to
the set point. The idea of
the stereo lithography system came first and then some bright guy
thought of using a system like a
HP inkjet printer which worked well. The major difference between the
two system is the Stereo
Lyth parts are smoother and have fewer "tie threads" to clean up. The
Jet rapid prototyping system
is super for larger parts. There was even a system that used paper
laminates that worked very
well. Again if you are already way ahead of me here I apologize. Bill
Jepson
No problem. thanks for the clarification. I think the term has been
broadened to cover some of the other 3D prototyping techniques. At
least this is what they call it at the college I go too.
Paul Lamar
Monty Roberts wrote:
As far as rapid prototyping goes, I regularly use all of the systems. They
all have good and bad points. Stereo lith (SL) parts are typically very high
resolution, but not necessarily the same mechanical properties as the
plastic parts that I am trying to test so it has limited use. It is
relatively expensive because the resins uses are expensive. It works great
for making patterns for silicone molds. Then you can cast multiple urethane
parts that can have the desired material properties. Use when a smooth
finish and high accuracy is essential.
The plastic layer and paper layer stuff is OK for just holding it in your
hand to get a quick Idea of what the part looks like. For serious use I have
been rather disappointed with the dimensional tolerances of this process.
Cheap, and you get what you pay for. Colleges and Universities typically buy
these because they are cheap, and illustrate the general Idea of the
process, very few serious people in industry use these machines.
FDM (fused deposition modeling) uses a laser sintering process similar to SL
but fuses a powder instead of a liquid. It is good for some things and can
model rubber, plastic, and even metal parts. Some of the material can even
be used to form cores for a process similar to lost wax casting.
Stratysis is the system I use the most. It is capable of producing very
large parts to a .015 in resolution. It builds up layers using what looks
like weed eater line. The ABS thread is fed into what is basically a glue
gun that melts the plastic and deposits it in layers. By far the easiest and
best way to prototype your typical consumer product plastic part. I send the
file in, fed ex delivers the part a couple days later, we assemble the
product and test it. The mechanical properties are typically about 80% of
what an injection molded ABS part would be. This process also can produce
cores for lost wax type investment castings.
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This is what I am using. I think the machine is called "Prodigy".
I wonder if nylon fishing line can or could be used? :-) PL
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The other system that works great is a 4 or better yet 5 axis machining
center and simply cut the part out if it is a fan or something similar. I
would think that this would be the best way to produce wooden core boxes for
a casting.
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The core boxes themselves will be cast aluminum using the plastic
parts made above as simple patterns. These are low cost castings and
all eight core box parts can be cast simultaneously. They can then
be polished if desired to get a very good finish. PL
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All of the prototype shops and most job shops are really hungry right now,
so I'm sure you could get a good price on anything you wanted to have done.
The plastic layer stuff may work, but I would really check the dimensions of
the finished part. They also tend to warp quite a bit.
Monty
I will be picking up my first part today.
Paul Lamar
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