Machining a TI-89 Out of Aluminum

TangoMargarine writes "Sometimes, expensive calculators hit the floor. It's happened to almost anyone with a graphing calculator from TI or HP. Sadly, they don't always bounce. After this happened to [Howard C.], an Industrial Engineering student from U. of Iowa, he decided to spend $50 on milling his own replacement case out of aluminum rather than trashing the device over a broken battery compartment."

Comments

ok but

[FuckingNickName]

1. Serious engineers use HP calculators;

2. Cushioned innards no?

Re:ok but

[Jeremy Erwin]

Well, he is an engineering student. He'll learn a valuable lesson that he can apply throughout his career.

Re:ok but

[Anonymous Coward]

I know this guy personally. The durability thing was mostly just the spin HackADay put on it. As I recall, he milled this thing out mostly because it was a good way to get more experience milling complex items out of aluminum. And because the final product is seriously cool.

More important: motherboard fittings, construction

[blind biker]

I've seen the drop-test instrumentation used for reliability testing in one of our uni's labs. They sell services to companies such as Nokia, to test the reliability of their gadgets. Anyhow, to make an almost indestructible case is not difficult, but what increases reliability and survivability of electronic equipment is correct fitting and damping of the motherboard to the case (you don't want it to feel the same deceleration as the case hitting the floor) and the components soldered on the motherboard must not break the electric contacts. This latter is very, very challenging, and hundreds if not thousands of engineers and scientists work around the world on improving the reliability of electronic IC packaging and solder.

Re:Why not...

[Bing Tsher E]

If he were to glue the battery cover on, how's he going to change the batteries?

He can throw on a black turtleneck, cop an attitude, and pretend it's an iPod.

Extra bonus points for throwing it away and buying a new one when the batteries wear out.

cost

[donnyspi]

I can't begin to understand why these calculators, which have been around for many years and still have the same features and functions, cost the same as they did when I was in school about 15 years ago. http://xkcd.com/768/

Re:cost

[soupforare]

They're test-legal and a de facto standard in schools. It's ridiculous but it's kept prices high as hell. The casio graphers are speedy, work well and are cheap. Unless you expect to be taking a placement test anytime soon, there's no reason to stick with TI.

Awesome. How do I do that?

[vadim_t]

I'd like to do the same thing. So I'm hoping somebody could give me a few hints on it.

First, how did he manage to come up with a design for the new case matching exactly all of the buttons? Do you just take some calipers and start measuring? The curved layout of the buttons, and the shape of the buttons themselves look tricky. Also I imagine that accurate positioning of screw holes is critical.

And second, how does one get such a thing manufactured? Are there places available to normal people that would take an order for a single piece or a small run, and what file format would they require? Or a place where I could get access to the hardware and operate it myself?

I would be really appreciate some pointers about how to get started.

Re:Awesome. How do I do that?

[aluser]

I haven't used this place, but here's one place that will do small one-off machining jobs for you: http://www.emachineshop.com/ . That's been sitting in my bookmarks for "future reference" for a while now :)

Looks like they want you to use their own cad software, which apparently can estimate the cost while you work on the design. I bet some googling can find other, similar, shops.

Anecdote

[rdnetto]

TIs are the standard amongst students where I live, I always thought that serious engineers use *computers* with MATLAB, Maple, etc.

Actually, this reminds me of a story I heard about a classmate a few years ago. He actually dropped his TI-89 (same one as shown here) out of a 2 story high window. The case was cracked but apart from that the calculator worked fine.

Personally, I think that model is the best one so far. It had full programming capabilities paired with tech. The new NSpires have a higher res screen, but they're not as easy to use because the interface is much more advanced and relies on a cursor. Additionally, programs are limited to BASIC, unlike the 89s which supported programs written in assembly (and TI even provided an IDE to write them in, IIRC).