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Hardware Hacking Handhelds Math Hardware

Machining a TI-89 Out of Aluminum 148

Posted by timothy
from the fully-weaponized dept.
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."
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Machining a TI-89 Out of Aluminum

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  • ok but (Score:5, Informative)

    by FuckingNickName (1362625) on Saturday August 28, 2010 @04:14PM (#33405030) Journal

    1. Serious engineers use HP calculators;

    2. Cushioned innards no?

    • Re:ok but (Score:4, Insightful)

      by Idarubicin (579475) <allsquiet@hotmail3.14.com minus pi> on Saturday August 28, 2010 @04:20PM (#33405060) Journal

      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.)

      • Definitely something to consider.

      • by ildon (413912)

        This was my very first thought when reading the summary, too.

      • Re:ok but (Score:5, Informative)

        by Anonymous Coward on Saturday August 28, 2010 @05:24PM (#33405348)

        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 (Score:4, Interesting)

          by Chris Burke (6130) on Saturday August 28, 2010 @06:16PM (#33405634) Homepage

          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.

        • by rwa2 (4391) *

          Awesome case mod, in that case.

          I hate to admit that I was that lazy, but when it happened to me, I ended up just memorizing the key locations and operating it without the case entirely :P

      • I heard this in the 1970s about a guy who had a timber seat on his hang glider. He crashed the glider and broke the seat. Rather than replace it he reinforced the seat with a strip of steel so it wouldn't break in future hard landings...

    • just use 5 cents worth of epoxy to put the broken piece back in place?

      -Rick

      • by bsDaemon (87307)

        If he were to glue the battery cover on, how's he going to change the batteries? I used to break the snaps off the battery covers all the time... started just using electrical tape. Fixed a TI-85, TI-86 and 3 TI-83s that way. I've had my TI-89 since 2000 or 2001 (got it some time in 11th grade, forget which half), but so far have avoided breaking anything on it. I might replace it with an HP50G soon just on general principles though.

        • by Splab (574204)

          Was thinking, what's wrong with plain old gaffa?

        • Re: (Score:2, Informative)

          by mysidia (191772)

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

          • Yeah, but you have to wait for bids to close, shipping, etc. I have an even simpler solution [wiringproducts.com] that I've used successfully for many household devices. Granted, the TI calculator presents some interesting challenges for engineering this solution, but I think a smart engineering student should be able to figure it out.
        • by Bing Tsher E (943915) on Saturday August 28, 2010 @04:55PM (#33405244) Journal

          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.

          • by exomondo (1725132)

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

            He doesn't have to go that far, he could just do what the Cupertino folks do to solve a major design flaw...whack a rubber band around it.

      • by evilviper (135110)

        just use 5 cents worth of epoxy to put the broken piece back in place?

        That was my thought exactly... BUT THEN I RTFA, took a look at the first picture of the old busted plastic case, and understood. Good thing, too. I'd hate to have posted a "why didn't he just..." comment on /. that makes me look like an idiot. Close call there...

        • by RingDev (879105)

          Did I miss something in the picture? It looked like the only broken part was the corner of the battery case. epoxy the broken piece back in, glue the spring back in place, and run a small lead from it back to the power line.

          Or does this guy have access to a 5 axis milling machine, but not a soldering iron?

          -Rick

    • Re: (Score:3, Interesting)

      by Desert Raven (52125)

      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.

      • by Chris Burke (6130)

        That's odd. When I was in school, TI calculators were preferred precisely for being designed to withstand drops from table height. Since the school was loaning them to students who didn't have one, this was a real concern. They were dropped onto the hard floor all the time, but breakage was really rare (and usually came from something like dropping them down a flight of stairs). I owned one for years that had been dropped I don't know how many times without a problem. Then it got swiped. Oh well it wa

        • by toddestan (632714)

          I've found that the screens on the HP-48 series calculators are kind of fragile. It's due to the LCD being snug against the front of the case and unprotected. If the calculator is dropped, the case can flex, and if the screen doesn't have room to move then it will break. The old TI's like the 81 and 85 have the screen inside the calculator, which is protected by a clear plastic lens. This makes it harder to see the LCD, but the screen kind of sits loose inside, it's nearly immune to breaking when the ca

          • by Chris Burke (6130)

            The old TI's like the 81 and 85 have the screen inside the calculator, which is protected by a clear plastic lens. This makes it harder to see the LCD, but the screen kind of sits loose inside, it's nearly immune to breaking when the calculator is dropped (my TI-85 has withstood an amazing amount of abuse and still works flawlessly). Note that the newer TI's (83+, 89) have the screen mounted like the HP's and thus seem more prone to breaking in the same manner.

            That makes a lot of sense. Like I said I don't

      • I agree. My TI-89 Titanium's lithium battery cover broke. Not only have I not dropped this calculator but I haven't ever replaced the lithium battery. The lithium battery cover apparently serves no purpose so I could just take it out and use only the main battery cover. I think they just put it in there so it could break.
      • by mlts (1038732) *

        The problem is that TIs are "good enough" (IMHO, of course), and have always been at best par for the course. The HP calculators are made to a much higher standard, and even though they are more expensive, for someone who relies on a calculator often it is worth it.

        One example is the engineering of the venerable HP-48SX. The memory card didn't just use a card edge connector, it had a well made shutter to protect the contacts when removed from the device. One doesn't see this type of engineering much anym

      • by YoungHack (36385)

        HP calcs are my favorite as well. But I will say that the 28S was not a durable calculator. I think I've broken at least 3. But I loved that calculator model. If they would have just done something to improve the battery door, they could still be selling them.

        • by pipingguy (566974)
          I agree completely. The 28s had a terrible battery door (now looking sadly at my dead 28s).
      • HP Forever! Not just a slogan, a reality.

        My HP-45 calculator is still going strong!

        http://img.skitch.com/20100830-3s3d9tu936f4wim7neihyej3f.jpg [skitch.com]

        It's faster to use the real calculator that it is to call up a calculator app on the Mac.

    • Re: (Score:3, Funny)

      3. Stop dropping your calculator? I have never damaged a calculator by dropping it.
    • by ukemike (956477)

      1. Serious engineers use HP calculators;

      Unfortunately HP no longer makes serious calculators. sigh.

    • Anecdote (Score:5, Informative)

      by rdnetto (955205) on Sunday August 29, 2010 @12:13AM (#33407104)

      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 [wordpress.com]) 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).

      • by walshy007 (906710)

        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

        I have an n-spire, and find the interface rather nice. You don't use the cursor at all after a short while, while it's there it's not really meant to be used for fast operation. And while true that you only have basic unless you hack the calculator, for actual math uses you really don't need anything more. Considering the extensive api it supports.

        For games it's limiting, but if I want to play games I'll pull out my laptop or DS.

      • by afidel (530433)
        The TI-89 is essentially embedded Maple.
        • by rdnetto (955205)

          But without the full size keyboard+screen and processing power of a desktop. Good for some applications (e.g. students, maybe if you need to do some math on the go), but for most a laptop/desktop with Maple would be a better solution.

    • Re: (Score:3, Funny)

      by ross.w (87751)

      Didn't you mean

      1. Engineers HP Calculators use serious?

  • Terminator (Score:4, Funny)

    by Xugumad (39311) on Saturday August 28, 2010 @04:16PM (#33405036)

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

  • by blind biker (1066130) on Saturday August 28, 2010 @04:38PM (#33405178) Journal

    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.

  • by Tumbleweed (3706) * on Saturday August 28, 2010 @04:39PM (#33405182)

    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.

  • I wonder how he measured the holes for the keys. That's the tough part. Once you have a good model, it's a simple enough CNC machining job. Although the front panel is thicker than the original, and the keys don't project as much as they should.

    It might work to simply put an undamaged calculator in a flatbed scanner, get a good image of the front, clean it up so it just has the hole outlines for the keys, vectorize, then clean up the vectorized form.

    Front Panel Express [frontpanelexpress.com] specializes in making panels w

    • Uh... (Score:2, Insightful)

      by 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.

    • by vlm (69642)

      I wonder how he measured the holes for the keys. That's the tough part. Once you have a good model, it's a simple enough CNC machining job.

      Not sure how you figure the machining is simple... Nothing funny at all about square cornered holes, or using extremely small endmills to simulate a square (radiused) courner. Yes I know the "+" sign is oval so no problemo, but look at the 2, 5, 8

      Also machining it thin enough to be usable/light will make clamping it to the table/fixture quite challenging. Make multiple positive and negative "molds" and machine small sections at a time to minimize bending? Its going to be a lot more complicated than "bolt

  • cost (Score:5, Interesting)

    by donnyspi (701349) <junk5&donnyspi,com> on Saturday August 28, 2010 @05:16PM (#33405336) Homepage
    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/ [xkcd.com]
    • by omglolbah (731566)

      Because they are required by most schools.

      The 'demand' is 'forced' so why should the price drop? The same group of people buy them every year regardless of the cost ;)

    • by hedwards (940851)
      Technically speaking that's not quite true, the newer ones have a bit more processing power and memory and use a USB cable instead of the old serial one, and they include it in some models. Additionally the resolution is a bit higher than on the older ones. But it's not really enough of an improvement to justify the lack of price drops over the intervening years.
    • Re:cost (Score:5, Interesting)

      by soupforare (542403) on Saturday August 28, 2010 @07:24PM (#33406034)
      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: (Score:3, Interesting)

        by MightyYar (622222)

        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 :)

        • Preaching to the choir. The drop in quality for the new HP calcs is disheartening though. I haven't played with 50 yet but the 49G/+es I've had were dogs. :(

    • by AdamHaun (43173)

      Do you want your calculator to have the battery life of a cell phone? Go ahead and put a fast CPU and a fancy backlit display on and see what happens.

  • by vadim_t (324782) on Saturday August 28, 2010 @05:36PM (#33405414) Homepage

    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.

    • by aluser (771756) on Saturday August 28, 2010 @06:12PM (#33405596)
      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/ [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.

    • by Grishnakh (216268)

      I'll take a couple of guesses.

      1) for the buttons, he used a scanner, and generated a pattern from the old case, and used that to generate a CAD file and then a G-code file for the milling machine.

      2) he's an engineering student, he probably had access to a CNC machine at school. There's tons of cheap CNC machines out there these days (even under $1k).

    • by DaveGod (703167)

      Look up CNC [wikimedia.org]. Probably quite expensive unless you have one at work or know someone using one at college - they'll be quite expensive capital equipment so while the incremental cost to actually use it is probably quite small, anywhere doing it as a business is looking to recoup the cost of the machine.

      (I'd be more helpful but I'd only be looking it up myself.)

    • As an engineer you'll draw the model in CAD using software like Solidworks. Then you'll use other software tools that let you program code to tell a CNC machine HOW to make your model from a solid block of aluminum. Then you feed the code into a CNC machine and let it go to work on the block. If you did everything correctly you have a new calculator case if you botched it, you have to start over.

      A local machine shop will be able to help you with this. CAD software is expensive but if you're interested in le

    • by SheeEttin (899897)

      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?

      Well, many of the buttons are in a regular pattern and of the same shape and size, just warped, so using calipers would be a little easier than you'd think at first. (Photo of original TI-89 Titanium and milled case here [wordpress.com].)
      After viewing all the pictures, though, it seems the holes are approximations of the buttons. Dunno how that'd affect debris entry.

  • by Len (89493) on Saturday August 28, 2010 @05:41PM (#33405440)

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

    • by rdnetto (955205)

      You jest, but he probably won't be able to use it for exams anymore, since it's clearly been modified.

  • He'd have gotten away with it if he didn't post the picture [wordpress.com]
    .
    It doesn't make sense to replace titanium with aluminum. Busted, mofo.

    • by MightyYar (622222)

      He says that the Titanium model is the replacement that he bought while he was fabricating the aluminum case for the broken unit.

  • by NixieBunny (859050) on Saturday August 28, 2010 @05:58PM (#33405522) Homepage
    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.
  • I really like stories like this. Where ever feasible, I try to repair rather than replace.
  • by SlashDread (38969) on Saturday August 28, 2010 @07:34PM (#33406074)

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

  • Coming soon: how to mill new floorboards out of titanium, after the old floor was shattered by a falling calculator.
  • Carbon fiber would have been cooler, thinner (what's with that raised edge and the fact that the buttons don't protrude at all from the face, that'd drive me nuts!) and a lot lighter weight, not to mention being easier to construct.

  • We had a bunch of TI-82s in high school. Our Algebra teacher helpfully explained that they had been engineered to withstand a waist high drop. Whenever one would inevitably slide off someone's desk, we would exclaim, "waist high!"

    I was the nerd who bought his own TI-83 and the Graph-Link cable to plug in to the COM port of his home computer.

  • Why not make the ground soft ? :)

    I mean, semi-seriously, all our shiny expensive toys are very fragile. If the greatest danger is having them hit the floor, then let's make the floor mushy and soft instead of these steel-and-concrete gear crushers.

    I'm sure I'd have gone through a dozen smartphones this year, if my apartment weren't covered in nice fluffy carpet.

    • by IorDMUX (870522)

      Why not make the ground soft ? :) I mean, semi-seriously, all our shiny expensive toys are very fragile. If the greatest danger is having them hit the floor, then let's make the floor mushy and soft instead of these steel-and-concrete gear crushers.

      ...

      Because some of us go outside?

  • Those engraved labels look kind of fuzzy...
  • Am I the only one who thought this guy was building a terminator ?
  • $10 bucks at hardware store... aluminum, only protective as deodorant for your sweaty palm... not so much for graphing calculator with screwed down pcb.

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