Tiffin Box From Tuna Cans

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Introduction: Tiffin Box From Tuna Cans

A tiffin box is a small lunchbox used to carry a tiffin, or light meal.  The lunchbox consists of a stack of steel or ceramic compartments for each food item.  According to wikipedia, the term originated in colonial India, and today in Mumbai there exists a complex network tiffin-boxed lunch deliveries on a massive scale.

I really like the utility and look of these lunchboxes, so I wanted to try making my own.  Tuna cans seemed like the perfect compartment -- the only problem was getting them to nest nicely.  I was really impressed with how well the can-shaping jig worked.  It pulled in the bottom of the can and made a uniform ring just above it.  After that, the cans fit together really well, and all I had to do was add draw catches and sand everything...and eat the tuna.

Step 1: Make the Can-Rolling Jig

The can rolling jig consists of two old door hinge pins and a hose clamp.  The heads of the hinge pins nest with each other.  By applying pressure with the clamp and rolling the can, we can raise a lip on the can's side.  Check out the embedded video in the next step to see it in action.

Building the jig is very easy.  In a piece of scrap 1x1 wood, drill two holes to accomodate the hinge pin shafts.  Space these holes so the pins are roughly parallel when the heads are nested.  Slip the hose clamp over the pins and stick them in their holes.  

The top pin will stick out further than the bottom on account of the heads being nested.  If everything works out, this should be enough so you can clamp the vise grips to the top pin and turn it through a complete revolution.  You may want to trim a bit off the bottom shaft to give yourself more room to work.

Use a vise to clamp the wood and hold the whole thing steady.  You're ready to roll.

Step 2: Prepare the Cans

Open the cans and eat the tuna.  May I suggest tuna salad with curry powder?

Wash out the cans and use the rolling jig on 4 of the 5.  The unrolled one will be the bottom of the tiffin box.  Test each can that you roll to make sure it fits inside the top rim of the others.




 

Step 3: Make the Lid

Mark one of the rolled cans evenly all the way around and cut it with the dremel tool.  Make sure to sand the cut edge smooth on the rolled half.  To make it fit inside the top compartment, crimp the lid using the stovepipe crimper.  Start conservatively and crimp deeper until you get a good fit.

Step 4: Make the Draw Catches

The draw catches will hold the stack together when in transit.  The draws get soldered to the bottom compartment, and the catches are sized to hook over the rim of the lid.

To solder the draws, first shape them to follow the curve of the can.  I hammered the draw on a wooden dowell to get the rough shape.  Once the draw and can fit together well, clean both surfaces and apply flux.  I held them together with vise grips and used a torch to heat them to soldering temperatures.  The inside of the tuna can has a protective coating that will burn off if you heat it too much.  When you're finished it will probably look ugly, but have faith in the power of wire wheels and sandpaper!  

With both draws in place, we need to fashion the catches.  I used welding rod for mine.  Take a long piece and fold it in half (both halves should be taller than the tiffin box).  Using pliers, bend the fold over to form the hook.  On the other side, form a sharp inward bend on each rod.  I used the vise to help with this.  Once the welding rods are shaped, trim them up and hook them into the draws.  

The draw catches should hold the stack together tightly but not pull so tightly that the cans deform.

Step 5: Finishing Touches

At this point, the Tiffin box is operational but probably doesn't look too nice.  I was really happy with how quickly the surfaces shined up after I used the wire wheel on my bench grinder as well as good old sand paper and elbow grease.  As always, start with coarse grit and move towards fine grit.

Last but not least, remember to re-wash the cans really well before use.  I don't make any guarantees about food safety -- tuna cans are certainly food grade, but when you heat them, strange things can happen.  Keep that in mind as you are washing and scrubbing those cans.

Go have a picnic and post pictures!


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    101 Discussions

    You could possibly use pop rivets instead of soldering.

    Way cool and well done! Thanks!

    Great idea except for one thing: you even mentioned the plastic coating inside the cans. That coating is called PBA and it is toxic.

    1 reply

    If it is toxic, how did it got in contact with foodstuff?

    PBA stands for poly butyl acrilate, and is a food grade cover, it might degrade after repeated washes, but in a tuna can is better alternative to tin, which might be contaminated with led.

    food industry (aside from what Chef Sonoma might say) has tight hygiene and safety standards, so don't worry too much about it, (start worrying if you heat the can, let it rust or otherwise compromise the interior, but that tends to be visible)

    Splendid

    0
    user
    gmk855

    2 years ago

    Use JB Weld instead of solder.

    what if you used the cans that came with tuna in oil?

    With the new can opener the toucan it removes the top of the cans and leaves no edges so u then also have the top in which you might be able to creste the seal and closer this needs? Not sure just a idea.

    Love it. Can't help but think of the movie Dabba as I was reading.

    My tuna cans already have rounded bottoms and fit together nicely for stacking. They'd work okay, wouldn't they? Thank you. C

    2 replies

    Yeah, but it won't provide an air tight closure, which is kind of the point of the tiffin pails: one can closes the one below

    The cans might STACK, but they don't close.

    Ahh, now I see. Thank you. I love this project, how it looks, what it was upcycled from and the DIY aspect. It's beyond my skill & tool level.

    I love it though.

    C

    This is one of the best Instructables I've seen, and the first one I've liked enough to comment on. This project really captures the spirit of DIY simplicity. The hinge pin roller is brilliant.

    I'd like to see this improved to have a liquid-tight compartment for soup or a beverage. Do you think a little food-grade silicone on the rolled bottom of one can, and a ring of the same inside the can it fits into would do the trick?

    4 replies

    For a silicon (RTV) seal.

    Use petroleum jelly on the bottom can's top rim inside an out. Apply an even thin coat of food grade RTV to the bottom mating can's under/outer mating surface. Let the can sit and dry/set up till a thick skin forms. Then mate the two together with a little pressure. Enough to move the RTV but not enough to get a metal to metal contact. Let set for 24 hours. Trim excess RTV wash and enjoy water tight seal.

    This is a "Perfect" fit and you will have to put the cans back together in the order and alignment you made them.

    you should do an instructable on that, it would make a great addition to this one

    You could also look into buying a pre-made silicone washer. Medical/ FDA grade are available. It'd be easier to clean/ replace (I run my moka pot's ring through the dishwasher with no significant breakdown after dozens of washes), and wouldn't leave you with any particles in the soup. Just make sure the clamps are quite tight!

    Might be possible to rivet a ring into the bottom of the next tier. Then you wouldn't have to be too cautious about verify the seal each time. Or raise a ring on the next tier inside the circle of the seal. Or soldier a guide ring around the outside....

    Great instructable!

    this is one of those great instructables where everyone can lettheir imaginations run and make upon it, i for one loved it,

    Congratulations!
    Your 'ible was featured in Make magazine online today!
    Here is the link to the article.

    Clipart-Congratulations.jpg

    We use tiffins for our kids' lunches. Love the way you made yours. Kudos!