Filing Cabinet Smoker

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About: A high school engineering student

A smoker is a cooking implement which uses wood smoke to flavor and preserve food. This process usually takes longer than standard cooking but is well worth the wait. The most important properties of any smoker are its abilities to retain smoke and hold food. This all started as a project for our high school engineering class so this is our first attempt at building something like this. There are definitely ways this design could be made better but we are still going to show you what we did so it can hopefully help you with your own projects.

Step 1: Acquire a Filing Cabinet

Choose the base for your smoker based on how much meat you want to smoke and how much work you want to do on it. Remember, bigger isn't always better. Older filing cabinets are usually made of thicker steel which will have better heat retention. Most cabinets will have paint which must be removed either by sandblasting or burning. We used an older cabinet for our smoker and we were more than satisfied with the end product.

Step 2: Remove Paint

This step is especially important in the process of making your smoker. The easiest way to do this is with a sand blaster or power washer which will strip the paint clean off with relative ease. If you don't have access to these materials, burning the paint off is the next best thing. You'll have to start a relatively large fire in the cabinet to get it good and hot but before you do so be sure to remove any essential components that you don't want damaged. After it has cooled some, you can use metal brushes to scrape off any remaining paint.

Step 3: Create Airflow

Smoke from the fire on the bottom must reach the parts of the smoker with food and eventually leave out the top. The best way to do this is to cut holes in the bottom of the drawers. Use an oxyacetylene cutting torch to remove part of the bottom of each drawer. Make sure to wear all proper safety equipment and use common sense. Once this is done you have to create two controlled openings, one for air to enter and one for smoke to leave. A flue at the bottom will be the intake and a chimney at the top will provide an exit. Again, use an oxyacetylene cutting torch to cut a rectangular hole on the bottom of the front face of the cabinet and a circular hole on the top of the cabinet. The flue was made by bending sheet metal into rails and sliding another piece of sheet metal along the rails. The rails were fastened with sheet metal screws to attach them to the cabinet and keep the sliding door from falling out. The chimney was made by rolling the same sheet metal into a tube and tack welding it so it stayed. Then a door that pivots on a screw was added on the top of chimney. The flue and chimney designs allow you to regulate airflow into and out of the smoker.

Step 4: Make Racks

These racks will hold the meat up off of the drawers. You can make these racks out of just about any metal you want but we used 3/4" angle iron. Each rack consisted of two running bars and multiple cross bars. The distance between each cross bar will depend entirely on what you want to smoke. Smaller things like chicken wings will require more crossbars that are closer together while larger items like pork shoulder don't need as many. As they won't be bearing much weight, you only need to tack weld the cross bars to the running bars so they stay together. Before smoking, you'll want to season the racks. This essentially means covering them in vegetable oil and getting them very hot. The oil will become attached to the metal and form a protective coating, this same method is often used with cast iron skillets.

Step 5: Install Heat Source

The most important quality of your heat source is its ability to burn at a very low heat. Depending on your preference you can use a standard fire, a propane burner, or an electric burner. We chose to use a propane burner because it's portable and doesn't have to be checked every half hour. The heat source should be installed as far away from the food as possible because you want to smoke instead of cook.

Step 6: Create Smoke

Now comes one of the most important parts. Your wood chips should be put in a metal tray or box and suspended above the heat source. There is a sweet spot where the chips are close enough that they release enough smoke but don't burn up too quickly. This will take adjustments so don't be frustrated if at first your chips burn up or smoke too little. If you find your wood chips are getting too hot and there isn't room to raise them up higher you can put your chip box in a tray of water. The water has a higher heat capacity than the metal and will only transfer only some of its heat to your wood chips. You can buy metal boxes that are made to hold wood chips or you can make your own which is what we did. We took sheet metal, bent it into the shape of a box and welded the corners. Then we filled the box with chips and set it over the burner.

Step 7: Finishing Touches

After a few tests, you may find there are some things you wish to add or improve upon. We found that smoke tended to leak from the back of our cabinet and we welded over where the smoke was escaping. A thermometer can be useful to monitor the temperature inside the smoker. We found that the drawer handles would get warm so we took metal coils and wrapped them around the handles. The coils remained cool to the touch and made opening and closing the drawers much easier. We decided to add a small prep table on one side to put meat on, which we made with some spare wood. You may also find that you lack appropriate BBQ themed decorations. We had some old bicycle chain laying around so we decided to make a pig which would be our mascot.

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    14 Discussions

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    dix-huit

    7 days ago

    Galvanised steel + smoker = poisonous. Same goes for shopping trolley BBQs/grills, don't do it!

    1 reply
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    nkinzel20dix-huit

    Reply 7 days ago

    None of the galvanized got hot, it was only used on pieces that would stay cool. We also made sure not to weld or heat up the galvy and specifically used screws to fasten any pieces.

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    yeet45

    7 days ago

    Awesome idea! I tried it out at home and it worked great! Very easy to make and very cheap. I steered clear of the Galvanized metal but i agree since the areas you used it in werent heated it shouldnt be a problem. Good work to all the students involved!

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    APMski

    7 days ago

    Great project, I love it. The bike chain pig is awesome. Got my first Time Author vote!
    My only concern is like the previous comment, galvanized steel. This is a zinc coating that is highly corrosion resistant but has a really low melting point. Breathing zinc vapor is very unhealthy, and even used to have a name like "welders disease" (or similar, can't remember). So do not flame cut, grind, weld, forge or generally heat galvanized steel. The good news is that the coating strips off very easily using muriatic acid (actually hydrochloric acid). This is commonly available, sometimes called concrete cleaner or etcher. Read the fine print as these can also be phosphoric acid based. I bought a gallon at my local Home Depot recently and it took galvanizing off a piece of metal that my son wanted to forge. Left a black coating that scrubbed off easily. Follow the safety instructions and do not play with fire as you use it as those bubbles are hydrogen gas.

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    nkinzel20APMski

    Reply 7 days ago

    Thank you for the compliments, they are very much appreciated. We were well aware of the zinc coating and it’s potential hazards. We specifically used screws and didn’t weld or heat up anything galvanized. The only things we used the galvy for don’t get hot, the wood chip box was not made off galvanized steel. Thank you for your concern, no zinc vapors were inhaled.

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    Trainrek7

    Tip 7 days ago

    Please don't use galvanized metal for anything you're going to heat! It gives off very toxic chemicals and fumes when heated! No joke.

    1 reply
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    nkinzel20Trainrek7

    Reply 7 days ago

    We only used screws on the galvy and made sure it was only used on areas that don’t get very hot. The wood chip box isn’t galvanized.

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    ncolaw20

    10 days ago

    what is the ideal temperature to keep the smoker at?

    2 replies
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    kkosharncolaw20

    Reply 7 days ago

    A 225° smoker temp is ideal for just about everything IMO. Monitor the internal temp of your meat to assure the safe and correct time to remove it from heat. There are countless Instructables and internet resources for all the specific meats and cuts. Good luck!

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    nkinzel20ncolaw20

    Reply 8 days ago

    It entirely depends on what you're cooking. Some meats, like chicken or pork, will have a higher done temperature than beef.

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    Makerneer

    10 days ago

    Cool idea, thanks for sharing!

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    ncolaw20

    10 days ago

    This thing looks amazing!!! How long did it take to build?

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    jefff71

    13 days ago

    Thats really nice work, can you set it up to run on charcoal?

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    seamster

    13 days ago

    This is such a clever idea. Thank you! I see used filing cabinets all of the time - some of them quite old, so likely to be made of thicker metal. Great idea!!