DIY: Trash Can Cold Smoker

cold smokerWhen I announced my idea to build a cold smoker I got a lot of strange looks from family and friends. There is, of course, the logical reaction: “if smoke comes from fire, how can you have cold smoke?” There is also the layperson’s reaction “ why do you need two different kinds of smokers?” And finally (and what may arguably be the most compelling) there is the aesthetic reaction “you are going to put that on our deck?” Agreeably, all of these reactions are valid ones. But if you have ever tasted an amazing Scottish salmon, or a perfect chorizo, then you know all about the magic of cold smoke. I have been reading Charchuterie by Michael Ruhlman and Brian Polcyn . It is a wonderful look at the art of curing and sausage making- something I have been ingregued by for some time. As Ruhlman and Polcyn note, our ancestors figured out early on that meat left over a smoldering fire lasted longer- the smoke cured it. Today we have the luxury of refrigeration, but that does not mean we need to lose a taste for things like bacon, prosciutto or guanchali. If you are interested in the details, click here to read on.

Anyone from the South East will gladly tell you about their favorite BBQ joint – wether its mustard sauces from South Carolina or a vinegary spicy mix from Virginia, everyone has a favorite. BBQ is an example of hot smoking; or basically, cooking with smoke. You bring the chamber up to about 250F and let the smoke impart the heat and flavor. With cold smoking the goal is simply to bring the flavor to the party without the heat. Some cold smoked items are already cooked when smoked, hot dogs fall into this category. Others are cured, often with salt and sugar, then smoked and left to air dry for weeks or longer. Any way you slice it, cold smoking will take most cured items to the higher level of porcine perfection.

hot smokerThat, in a nutshell, is what led me to my Trash Can Cold Smoker. Ruhlman and Polcyn acknowledge that most smokers capable of cold smoking crest the $1,000.00 mark rather quickly and require some what of a professional operation to run. They do recommend a $450.00 model which has modest results. Having already built a $40 hot smoker based on Alton Brown’s terracotta pot design , I was fairly confident that I could apply some kind of McGyver engineering to the cold smoke problem. While we waited for polyurethane to dry (which has the mild advantage over paint of having fumes that will knock you out, but otherwise is of equal interest), my dad and I put our minds to the challenge. What we came up with is either an homage to L. Frank Baum or a wonderful cold smoker- the Trash Can Cold Smoker. With little more than $70 in parts, we were able convert my hot smoker and a galvanized Trash Can into a very functional cold smoker.

Parts Required

parts
1 Terracotta Pot Hot Smoker – there are various sources, but I recommend finding a copy of the original Good Eats episode.
1 large galvanized trash can
1 8 foot long x 4 inch diameter flexible dryer duct
2 4 inch duct take offs – usually in the duct work isle of the hardware
2 worm drive duct collars – also in the duct work section
1 vent cover – again, duct work isle
1 role Nashua tape or other metal duct tape – avoid traditional vinyl duct tape
1 terracotta saucer or dome pot to function as a lid for the smoke chamber
1 19 inch grill grate
1 21 inch grill grate
8 small “L” brackets with hardware or 8 small nuts, bolts and washers
Optional Parts
Computer fan – any low voltage fan, check radio shack or CompUSA
18 gague bell wire – any two wires should work
9 volt battery case
low voltage switch

Tools Required

Sheet metal or tin snips
pliers
drill with masonry bit (hammer drill may be preferable)
Wood/Metal bit for drill (hint: most regular drill bits are made for metal as well as wood)
rubber mallett or hammer
screw driver

Attach the intake to the Trash Can

The first order of business was to attach the dryer hose to the trash can. Since we want the smoke to rise and fill the chamber, we attached it close to the bottom.
1.Use one of the 4” take offs to trace an outline of the hole.
2.Using a regular wood/metal bit, drill a hole just inside the outline you traced
3.work the metal snips through the hole and begin cutting out the hole – when in doubt, err on the side of making your hole too small rather than too large. Try and fit the “tabbed” side of the take off through the hole, if its a little snug remove just enough of the metal to get a good fit.

cut hole
4.Bend the tabs of the take off flush against the inside of the can

tabs
5.using four sections of Nashua tape, make a square pattern around the tabs. Overlap a little of the tap around the inside of the take off, so that it overhangs the hole. Then carefully rip and bend the tape back inside the hole. At this point the tabs should be covered (to avoid sharp edges) and you should have a good seal.

snug fit
6.Using either small (1 ½ inch) pieces, or longer pieces with partial vertical tears, being taping around the outside of the takeoff. Again, the goal is to ensure a proper seal to the trash can.

box tape.

outside tape
7.Loosen the worm drive collar as much as possible and slip it around the take off’s protrusion from the can.
8.Slip about 3 inches of the flexible duct around the take off.
9.Slide the collar over the duct and secure it with a screw driver

collar

With that done, its time to manufacture the lid. This is a little tricky since it involves drilling terracotta, something notoriously prone to cracking. I found that saucers work quite well since they are rather thick. I have successfully drilled two out of two saucers, nevertheless you may want to buy a backup. Alton Brown’s design called for a bowl pot which would function as a dome lid – I love the idea, but I’ve not been able to find one at either Lowes or Home Depot.

1.Again, use the other 4” take off to trace an outline in the middle of the saucer.

trace
2.Working just inside the line, being drilling a series of holes using a masonry bit. It may help to make as few as four holes around the ring, then being filling in the gaps with another four holes, evenly spaced. That helps avoid weakening one area before the other side of the ring is ready to be knocked out

drill

holes
3.after you have established a good ring of holes (more holes than connecting terracotta) being working across the hole by making an X pattern across the inside of the hole.
4.Make another X so that you have a star pattern across the inside of the area to be removed.
5.By now the area should look like swiss cheese, start in the center and with short and deliberate strokes, knock it with a hammer. If done right, small sections should fall out. Work back towards the edge

hammer
6.(Optional) using a grinding disk in the drill or a Dremel tool, you can smooth the edges of the hole
7.confirm a snug fit with the 4” take off
8.Repeating the process from the trash can, bend the tabs inside the lid as much as passable. The thickness of the lid may make a flush fit difficult. A pair of pliers will help you get a better grip.
9.Working with short 1 ½ “ sections of tape, begin taping from inside the take off back to the lid. Work around the hole, overlapping the tape
10.Use for longer sections to tape a box pattern around the short piece. Again, overlap the hole and carefully fold the tape inwards.

tape lid
11.Use short sections or the tearing trick from step #6 above to seal the outside of the take off around the top of the lid
12.slip the second 4” worm drive collar around the protrusion of the take off

Building and attaching the chimney is very similar to attaching the take off to the can. While I worked away with the masonry drill, my dad painstakingly crafted a damper to fit inside the flue to regulate the smoke escaping. This is totally optional, you might also look for the a replacement grill vent and use that.
1.Trace an outline
2.drill inside the outline
3.use metal snips to remove the inside of the outline
4.make 3/4” vertical cuts around the bottom of the chimney, spaced about 3/4” apart. In other words, create tabs similar to the ones found on the take offs
5.bend the tabs back against the inside of the trash can lid

tabs in
6.Secure with box pattern of 4 pieces of tape
7.secure the outside against the top of the lid with more tape

smoke stack

We are almost done, now its time to mount the grates. You’ll want to space these vertically in the can so that you’ll be able to fit both large resting items as well as hanging items. You might even put in extra brackets to make them adjustable. This can be done with brackets, or simply with bolts.
1.For the lower grate, pick a distance off the bottom of the can. We wanted to leave room for some ice in case we wanted to smoke on a warm day. Measure up about 16” from the bottom of the can.
2.Make 4 marks around the can at your desired height (ours was 16”). You can count the ridges in the can to space the marks evenly.
3.Drill a hole that is only large enough for your hardware (either hardware for the “L” brackets or just bolts secured with a nut and washer)
4.If you are using brackets, attach them with the provided hardare. We secured our ½” “L” brackets with small wing nuts and lock washers. If you are using bolts, push the head through so that it is flush with the outside of the can, secure it with a lock washer and nut.
5.Repeat the process for the upper grate.
6.Optional, you may want to even install hooks on the lid for hanging items. We did not since hooks can always be hung from the upper grate.
7.Seal the outside of any holes, screw and/or bolt heads with more tape.

Now for the final assembly. No matter how many terracotta saucers we tried, none were a perfect fit for our hot smoker. That means some smoke leaks out. One options would be to find some weather stripping or oven insulation (avoid things with lose fibers that might become airbone and get into the smoke). We elected to use two damp rags to seal the lid to the hot smoker.
1.Wet two old dish rags and ring out the water
2.role them up and use them to make a seal between your hot smoking chamber and the saucer “lid”
3.place the lid on top of the hot smoker

rags
4.pull the flexible duct away from the body of the trash can
5.attach the lose end of the duct to the take off on the lid, secure with the collar and worm clamp

Thats it, you are ready to smoke! Of course you’ll want to pick a wood and get the hot smoker fired up, but otherwise things are ready to role. You might notice that we have not taped the duct work to either the trash can or the saucer “lid”. That allows us to disassemble the contraption, which can be a bit of an eye sore, and hide the parts inside the trash can. It also allows us to replace the duct work as it wears out.

While the smoker works well as a “passive system”, I have elected to retrofit mine with a small fan. For about $10 you can get everything you’ll need from your local radio shack. I mounted a small computer case fan inside the trash can where the smoke comes in. It draws the smoke from the hot smoker a little more effectively and even helps cool it in the process. I ran a short section of 1 pair bell wire inside the can and covered it with more Nashua tape. I secured a 9 volt battery housing and switch on the outside of the can. Presto, the passive system became an active one!

Ideally you want to maintain a temperature of around 80F inside the smoker- something that may be difficult to do on a warm day. I plan to experiment with ice in the bottom of the trash can or possibly even packed around the can itself.

There you have it, the Trash Can Cold Smoker. final

 

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  • Anthony

    Hello Nick,

    I have a hot smoker and was planning on using it to feed a cold smoke chamber. I was going to start with a cardborad box for that. I live by Cleveland Ohio and I am actually concerned about maintaining 80 deg in 20 or 30 deg weather. What is the coldest wheather you have used your cold smoker? Is low temp ever a problem?

    Thank you,

    Anthony

  • Anthony

    Hello Nick,

    I have a hot smoker and was planning on using it to feed a cold smoke chamber. I was going to start with a cardborad box for that. I live by Cleveland Ohio and I am actually concerned about maintaining 80 deg in 20 or 30 deg weather. What is the coldest wheather you have used your cold smoker? Is low temp ever a problem?

    Thank you,

    Anthony

  • http://www.nickdawson.net Nick

    Anthony – great question!
    In your case, you are in luck – cool temps do not pose a problem at all, in fact they are a blessing in disguise for cold smoking. The “bacterial danger zone” is 40F – 140F, in the case of most cold smoked items you cure them with enough salt that its safe enough to take them up to 80F for a period of 8 hours or so.

    Long story short, there is not really any detrimental effect to being colder than 80F, its actually even safer. The only problem I could foresee is actual freezing temps. In the case of below 32F, you might shorten the distance between your hot smoker and cold chamber to keep things inside from freezing.

    Good luck and please keep me posted!

  • Nick Dawson

    Anthony – great question!
    In your case, you are in luck – cool temps do not pose a problem at all, in fact they are a blessing in disguise for cold smoking. The “bacterial danger zone” is 40F – 140F, in the case of most cold smoked items you cure them with enough salt that its safe enough to take them up to 80F for a period of 8 hours or so.

    Long story short, there is not really any detrimental effect to being colder than 80F, its actually even safer. The only problem I could foresee is actual freezing temps. In the case of below 32F, you might shorten the distance between your hot smoker and cold chamber to keep things inside from freezing.

    Good luck and please keep me posted!

  • http://www.coupontrunk.com Coupons

    Thanks for the inspiration on making my own cold smoker. I can't wait to get started on this.

  • Jeff

    Hey there Nick,

    So, did you ever try with ice? Were you successful? I'm thinking of trying this but I'm a little afraid of the Texas summers… I was thinking of making a separate cooling box in between the two cans that is fitted with ice and electric fans. That way, instead of just leaving ice in the bottom of the metal can I could actually blow in cold air. Not sure if this would be better, but I'm just curious how it worked. Thanks.

  • http://www.nickdawson.net Nick

    Jeff,
    Thanks for asking!
    The good news is that I'm still experimenting and have had some success. The bad news is that its far from perfect and I think we can forget Texas heat…I can't even lick Virginia in the spring.
    You hit the nail on the head – the only way I can think of is to encase the entire trashcan in another chamber…OR find a way to introduce cool air with the smoke.

    I'm thinking of borrowing an idea from those “DIY dorm room Air conditioners” … find a way to pipe cold water around a coil and blow air across it. I think it could be done and I'm thinking of trying this summer…

    The challenge, as you well know, is that cold smoking takes so much time that even 30-60 minutes above 40f is pretty dangerous.

    please keep me posted on what you try!

  • http://www.atomsmokes.com/ Jimmy

    Nick,

    Don't forget that hotair rises, and therefore pushs the cold air down. It would be best to have a shelf of ice on the top of the chamber, than in the bottom.

    Give it a shot.

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    I'll post the same information to my blog, thanks for ideas and great article.

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    I really appreciate your step by step guide. Thanks so much!!!

  • http://twitter.com/Eatapedia Eatapedia

    Hi Nick,

    Thanks for this great article, you have certainly inspired me to try one out! How have you come along as far as temp controls go? I have a Traeger, and the exhaust I have hooked up to some dryer hose, but it’s still rather warm, say 140ish. Did you try the ice shelf?

    Thanks!

  • http://www.nickdawson.net Nick

    Thank you so much for the kind words Etapedia!
    I have done some ice in the bottom on a few occasions – I’m not sure the thermal dynamics are exactly perfect, but it does work to keep the smoke and chamber cool.
    Good luck and keep me posted on what you build!

  • http://eli.lansey.net Eli

    I’m interested in the damper your dad made to regulate the chimney ventilation. How did he make it? I’m looking to do something similar.
    Thanks!
    And great post!

  • Kevin L

    Love the design! Have you considered adding a few holes at the bottom of the trash can, and then placing the trash can on top of a washtub full of ice? You could even add salt to the ice to decrease the temperature. Just a couple of thoughts from a fellow smoker fan.

  • http://www.nickdawson.net Nick

    Wow Kevin, awesome idea about the ice! I’ll have to give that a try and report back.

  • John Rush

    Nick,
    I’ve been looking for a cold smoker for years, but didn’t want to spend $500 + for one, when I saw yours and it looks perfect. I will be making on soon.
    have you had any luck with the colding the smoke?
    I have a few ideas and would like to know what you think.:
    What if you cut the flex vent hose in the middle between the the hot smoker and the garbage can and put a 1 to 2 feet piece of steel pipe (4 inches diam) clamping with the worm clamp. Then cover the stell portion with ice, cooling down the smoke before it gets to the can.
    Another thought was to use a old ice chest running the pipe through the the chest sealing the holes with a water proof sealent, then filling the chest with ice. It would cool the smoke as it passes through.

    John R

  • http://www.nickdawson.net Nick

    John, thanks for the kind words. Good luck building something, I think you’ll find it economical and a fun project! I love your ideas for cooling the smoke, particularly the idea of running it through an ice chest of some kind. Truthfully, I haven’t had the need to really tackle the problem; I’ve been doing most of my cold smoking in the cooler months. Good luck and keep me posted on what you do!

  • Bsmiley

    Hi, I used a plastic dryer deflector that is used to recycle dryer hot air inside the house in one position and outside in other. If you have a right angle before it it will stay where you set it, it was about $7 several years back.

  • http://www.nickdawson.net Nick

    Thanks guys!

    Bsmiley the dryer vent sounds like a great option!

    Eli, my old man is crafty like that. He took a dryer vent sleeve and some scrap metal and fabricated the damper. You could get real close with a premade small chimney capper.

  • Bsmiley

    Hello Nick! Thanks for your work! Like you, I followed Alton’s tips and built his Terra Cotta Smoker years back, just after his show was on Food TV. I used a “Anti Spatter Screen(13 inch dia.)”, a stainless cheepo fine mesh ring after cutting off the handle to support items to be smoked above the smoker bowl on the hot plate. In your reply to John R. I had done the trick using an Ice Chest and duct parts to “cold smoke” duct breasts I over-smoked the breasts as well as over-cured them. Live, do, and learn from my mis-steaks (forgive the pun). I will be happy to post pix via email to anyone who wants. Bill Smiley

  • Brad7chellie

    What about dry ice to keep the chamber cool?

  • http://www.nickdawson.net Nick

    Great idea Brad! We’ve had a nice cool winter so I hadn’t had much of a need to cool things off. I’ll give dry ice a try sometime this summer along with the other great ideas that have been shared here.

  • http://www.nickdawson.net Nick

    Bill, thanks for the great comment. Its neat to find someone else who has followed the alton path; sounds like it was successful for you too. I like your suggestion about using a mesh ring!

    Sadly, thanks to starting a graduate school program (in addition to my full time job) I haven’t had much time to spend in the kitchen (indoors or out)…. so keep the comments coming! I’m living vicariously though ya’ll!

  • http://www.refusecompactors.org.uk refuse compactors

    In the world of charcuturie, cold smoking is applying smoke to meat without much heat in the attempt to get the smoke flavor into the meat without cooking the meat. The most common examples are bacon and smoked salmon, which are both basically uncooked by the smoke.

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  • Dbutz82

    I don’t think galvanized is the best choice. Heat+ Galvanized = Neurological damage  

  • http://www.nickdawson.net Nick

    Dubtz82 – totally appreciate that concern, and, at times, share it. The goal of cold smoking is to stay under 100f – cooler than the inside of the can would reach on a hot summer day. Generally, I only cold smoke in the winter, to avoid bacterial concerns. Still, there is that linger thought about using galvy in food prep at all. I think it merits research for anyone interested in doing lots of smoking. 

  • Padraig

    good  job  brother