Cadalyst - February 2008 - (Page 38)

mcadmodeling Low-Cost Rapid Prototyping These affordable machines can make whatever you want. By Mike Hudspeth, IDSA twentieth century! Think of an early stage of Star Trek’s replicator device. It’s a machine that makes whatever you want it to — without the need for expensive tooling. Y ou’ve been designing your heart out, and now you think you’ve got everything to the point where you feel physical prototypes are necessary. You have several choices to make. In the good ol’ days, you would need to make fully detailed drawings and send them out to a machine shop to produce models. It took weeks to get them back only to find that changes needed to be made. It would take several iterations before you could gain enough confidence to sign off on the design and begin preliminary tooling. Then you had to have enough prototypes for testing. The tooling would give you that ability, but by then if changes needed to be made, it was both hideously expensive and time consuming. Funny how those days don’t sound so good anymore. But nowadays things are different — and better. We can do it. We have the technology. We can make prototyping better than it was — and it won’t cost six million dollars, either. Nowadays, we can opt for a rapid prototype. What is that? Well, where have you been? Rapid prototyping (RP) is only one of the most exciting technologies to roll out of the The Technology Within To be sure, different machines use different technologies. Most of them start out with the venerable stereolithography (STL) file. This is a file that allows the RP machine to slice your computer model into thin layers — some thinner than .005 inches — and enables the machine to build and stack each layer one upon another until the whole part is finished. This process is known as an additive process. It adds material to make the parts. Another technology is stereolithography, which relies on photocuring resins with lasers. Some machines use powders that are sintered together with light or electricity. Others use fine plastic strands that feed through a heated head. Others are available as well, but I’ll confine my discussion to these for the time being. One thing that has been common among all RP machines is their high cost (some have been several hundred thousand dollars). Other common traits are expensive materials and controlled working environments. Historically, these things have made RP the niche business of specialist vendors, but times are a-changing. Prices are coming down. During the past few years, a quiet revolution has been taking place that is sure to have wide-ranging effects for everybody. Desktop 3D printers now are in the $30,000 and below range. What’s the difference between these and regular RP machines? The 3D printers generally don’t need controlled environments. The materials aren’t as expensive — although I might get some argument there. Unfortunately, the parts Figure 1. By tracing each layer of your computer model, you can create marvelous physical models that you can hold in your hand. they produce haven’t been as high resolution as those made by higher-priced machines, and the surface finish hasn’t been quite as good. But for a fraction of what you’d pay for a full-fledged RP machine, you can get physical models of your designs. And if you do a lot of RP, it doesn’t take long to justify buying your own machine. Let’s look at a few of these machines. The Players Obviously, I can’t cover all of the lowcost RP machines that are available, but I will hit on the highlights. First up, and probably most expensive, is Stratasys. Stratasys ($30,000, figure 1) is continually lowering the price for professional RP. Although several technologies are available, the one Stratasys uses is fused-deposition modeling (FDM). It uses filaments of engineering plastics that pass through a heated head to draw each layer. The resolution is usually limited to ±.005, so if you design with smooth curves, you’ll end up with the infamous stairstepping you find in most RP technologies. The model also will have a fairly porous texture because of the fusing of the filaments, but you can seal it with a solvent. In this article Desktop Factory www.desktopfactory.com Evil Mad Scientist Laboratories www.evilmadscientist.com Fab@Home www.fabathome.org Roland DGA www.rolanddga.com Stratasys www.stratasys.com Z Corp. www.zcorp.com 38 February 2008 | cadalyst | www.cadalyst.com http://www.desktopfactory.com http://www.evilmadscientist.com http://www.fabathome.org http://www.rolanddga.com http://www.stratasys.com http://www.zcorp.com http://www.cadalyst.com

Table of Contents Feed for the Digital Edition of Cadalyst - February 2008

Cadalyst - February 2008 Contents Editor's Window CAD Central Tech Trends More than Meets the Eye — A Look at Today's CAD Viewers IronCAD v10 — 3D Modeling Software AcceliArch with AcceliCAD — Add-In Architectural Drawing and Modeling Software CAD Manager MCAD Modeling AEC Insight CAD Cartoon Issue Indexes Hot Tip Harry

Cadalyst - February 2008

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