Anyone have experience with rapid prototyping technology (LOM, SLS, etc.)?

Discussion in 'Home Theater Projects' started by Jeff Meininger, Jul 12, 2003.

  1. Jeff Meininger

    Jeff Meininger Second Unit

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    I think there's demand in the DIY audio crowd for some nice 6" port flares. The Aeroport PNR is too difficult to obtain, and from what I've read has a few drawbacks making it more difficult to work with than it could be.

    First and foremost, finding the right kind of PVC to mate to the flares is difficult. Even if you DO find the right type of PVC and the flares fit onto it, I believe you have to sand the inside of the tube down so that the seam where the flare and tube meet is flush. Yuck.

    Also, there is no "mounting flange" on the Aeroports like there is on the familiar 4" precision ports. The mounting flange gives you a huge amount of flexibility and makes installation easier and more secure.

    I've been toying with the idea of modeling my own, better design for a 6" flared port. One that fits the most commonly available type of 6" ID PVC pipe, has a nice mounting flange, is thick and strong, etc. The idea would be to use rapid-prototyping technology to build the actual flares. I have no desire to invest in injection molding or get into the business of selling flared ports. [​IMG]

    My first question for you folks with RP knowledge: is this possible? For example, would a 1/4-inch thick LOM prototype be strong enough to hold the weight of the PVC pipe? Would humidity make it expand or contract? Would the surface be smooth enough, or could it be made smooth enough by sanding/painting?

    Next question: Would it be cost-effective ($60 or less for a pair of flares) to bring these things into reality?

    What I'd like to do is produce a sliced CAD file, put it on my website for DIY subwoofer hobbyists to download, use, modify for their purposes, etc. Free of charge, of course. I'd also like to find a hobbyist-friendly RP service bureau that can produce them relatively inexpensively for us DIY folks.

    What do you think? Is this a pipe dream (pun intended)?
     
  2. Jeff Meininger

    Jeff Meininger Second Unit

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    There are many different RP technologies... some use resin, some use wax, some use paper, etc. The technology that I think (uneducated guess) would work best for this application is "Laminated Object Modeling" which takes thin sheets of adhesive paper and laminates them together in thousands of layers, resulting in an object that's supposedly similar in look and feel to wood. I think they're supposed to be relatively strong, but not very resistant to moisture.
     
  3. RichardHOS

    RichardHOS Second Unit

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    I'm not current on the latest RP technologies, but my hunch is that you'd never have an economically viable port produced from rapid prototyping. Those machines are very expensive, and if you were to just farm out the work to an RP house to have them make the ports for you, they would charge you an arm and a leg for each one. A couple of hundred a port wouldn't surprise me... perhaps the price could come down a bit if you had them make a run of hundreds - but then again RP isn't about quantity production at all, so they might just have a fixed hourly charge for the RP machine time.

    Also (and again, I'm not current on the very latest RP technologies), I don't think the actual part would be suitable for mass market. I've seen RP used to make engine heads for flow testing, which is sort of a functional part. I've also seen a sand-RP (yeah, it was really odd) used as a mold to actually cast an engine block. I suppose that one was functional. But for a port you're talking about some resin/polymer technology, and though the gears and other such demonstration pieces I've played with were pretty nice, they didn't have quite the strength or uniformity I think you'd want for a marketable product.

    If you're serious about this, you'd have to go with injection molding. It's really not that scary. If you can do the solid CAD modeling for the port, then a molding house that sources small jobs like you're talking about could probably work with you on mold tooling. Producing mold tooling is nothing for a modern CNC machine, and for the quanties you're talking about a single metal mold would probably suffice. After the up-front costs, the molding house could supply the ports to you at a reasonable cost... hopefully reasonable enough to turn a profit on.

    If you go that route, though, it would be wise to seek the assistance of a plastics/injection engineer to advise on how to model the part so that it is suitable for an IM process. Things like draft angles and thin-wall warping have to be considered.
     

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