|Re: machined housing|
Message #10 Posted by Hugh Evans on 29 Nov 2004, 2:10 p.m.,
in response to message #1 by Jeff Brower
Machining an enclosure from a solid block of material is one of the more expensive ways to go, even if there were no tooling costs to speak of. The real problem is that so much material is wasted in the process. There are benefits to such an approach, such as improved strength properties. Since we're talking about calculators and not engine blocks, I think it would be overkill.
Let's look at some more practical options: Vacuum/pressure forming, die casting, and injection molding. Vacuum/pressure forming is by far the most economical choice for the kind of enclosures we're discussing. Tooling is dirt cheap (only in the thousands) and it works very well for small runs between 1 and 50-100,000 units. At that point injection molding is a better option. Die casting is more or less metal's answer to injection molding.
I've spent a good deal of time looking into manufacturing enclosures for the OpenRPN project. After going through many options and quotes it looks as though we will be going with injection molding (possibly an ABS/PC blend). The dimensions of our machines will be the same as the voyagers and pioneers and all of the holes for keys, LCD, etc. are going to be laser cut. So if the innards of voyagers and pioneers can be retrofitted I see it as a win-win situation.
PPU of the enclosures will be in the neighborhood of $10US. If there is any interest in this idea I can post some renderings of the plain enclosures.
Jeff, feel free to send me an e-mail if you have any other questions about this topic. I'd be happy to help.