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

[Idarubicin]

2. Cushioned innards no?

I was just thinking the same thing. If you drop the plastic case, it deforms slightly on impact (or fails, as it did in this case), protecting the circuit boards and display from at least some of the shock.

The next time our engineer drops his calculator, the milled aluminum case will remain pretty and pristine, just as planned -- but without proper cushioning, the plastic circuit board screwed to it will fracture. (If the innards are free to move a bit, I also wonder if the buttons are all going to get sheared off when they bump up against the aluminum frame.)

Re:ok but

[Desert Raven]

Agreed, I went through a couple of TI calcs before buying an HP. I've never had an HP break. That's not to say I haven't dropped them. My poor HP 11C is now over 25 years old, and has been dropped too many times to count. It's still my favorite calculator. My 48G has likewise seen some rough handling, it is also still running fine.

TIs are decent from a functionality point of view, but they are unable to take any kind of rough handling.

My wife used TIs in college, and went through a couple of them as well.

Re:ok but

[Devout_IPUite]

3. Stop dropping your calculator? I have never damaged a calculator by dropping it.

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.

Re:ok but

[Chris Burke]

Yeah, and according to the comments he left, since he really needed a calculator he ended up buying a new one before finishing this project, so the aluminum TI-89 sits at home instead of traveling with him. So the lack of shock resistance in the new case is probably not a big issue anyway.

Re:ok but

[ross.w]

Didn't you mean

1. Engineers HP Calculators use serious?

Terminator

[Xugumad]

Anyone else disappointed this wasn't an obscure Terminator model?

Re:Terminator

[PotatoFiend]

Uh, like the original? :D

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.

He is no Jedi

[Tumbleweed]

No duct tape fix, not an industrial engineering student worthy of respect. He could make a fine machinist, though. He should go with his true talent.

Re:Why not...

[mysidia]

There's an easier more elegant way than machining a new case to fix a battery cover, that's for sure.

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.

Uh...

[Anonymous Coward]

He DID have a template. He had to remove the innards from the stock body, leaving an easily scanned front case that will produce high contrast hole outlines.

As noted, the new casing is too thick for proper button operation. Also, the imprinted legends have poorer contrast than on the original body. Not a bad hack, but I'd prefer the original case. His reminds me of homebrew projects stuck in featureless Hammond boxes.

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.

Re:cost

[MightyYar]

The casio graphers are speedy, work well and are cheap.

I used Casios for years until I was converted into the RPN religion. Casio had a algebraic entry system that was ALMOST as fast and clear as RPN, and the calculators were much, much cheaper than the TI models.

Of course, now I've gone RPN and I'm spoiled - even have to seek out software RPN calculators for all my computers and devices :)

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.

Now he's in trouble

[Len]

TI's lawyers will be after him for DMCA violation because he's bypassed their physical copyright protection mechanism.

I'm working on an aluminum HP 11

[NixieBunny]

but it will use Nixie tubes for the display, just to make it interesting. It's fun to do the CAD design. Someone else will have to help me with the software, as I'm more of a hardware guy.

Re:Aluminum

[Chris Burke]

Since this project would have been for a machining class, not a case design class, I'd think a higher grade than that would be appropriate.

Re:Slashdot Delay

[Grishnakh]

Slashdot isn't a cutting-edge site for whatever particular niche you're interested in. It's a more general-interest site, with lots of different topics of interest (politics, free software, mathematics, games, etc.), so it's a little slower, but has a wider breadth.

repair rather than replace :D

[ksandom]

I really like stories like this. Where ever feasible, I try to repair rather than replace.

Wait this guy broke a TI 89 -Titanium-...

[SlashDread]

and replaced it with Aluminium? Isnt that a step back? Whats next? Casted iron?

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).