Instructables
Picture of Homebrew Cold Smoke Generator
Control your smoke independently of your temperature! Generate as much or as little smoke as you desire, for as long as you like! Cool and smoky, hot and smoky, anywhere in between, it's up to you!
 
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Step 1: Optionally, Add a Cap

Picture of Optionally, Add a Cap
A cap will allow you to stop the smoke generator at any time and save the remaining wood for the next smoking session.

Step 2: The Players

Picture of The Players
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Main ingredients:

a 12" (more or less) piece of 3" Schedule 40 aluminum pipe (available from Online Metals, Speedy Metals, McMaster-Carr Industrial Supply, etc.)

One (or two, if you decide to make the optional cap) 2 7/8" fence post caps, available from your local fence supply.

A piece of stainless steel screen, from your local hardware store or industrial supply.

A fitting for your air hose, a washer that fits over the threaded part of the fitting, and a brass pipe coupling that acts like a nut to secure your air hose fitting from the back side.

Not shown here:

a short length of 4" metal dryer hose ducting

a sheetmetal 3" to 4" duct adapter

a 4" duct cap

some duct tape (I used Gorilla Tape)

a couple of 4" hose clamps

Optionally, if you decide to make the top cap, a wooden drawer pull knob and a short screw.

Please, be safe and avoid the use of toxic materials, like zinc or cadmium plated steels.

Step 3: Take This Pipe and...

Picture of Take This Pipe and...
...go to your local fence supply. Try to find a loose fitting fence post cap for the optional cap end, and a snug fitting cap for the air end. Bigger is better for the air end - if necessary, you can drill a hole into the cap for a nut and bolt and chuck it up in a drill press or drill motor. A wood rasp or coarse file will make short work of any cap that is too large. Try to file a tapered shape so that the cap will enter the aluminum pipe about halfway, and then use a hammer and a block of wood around the ribbed part of the cap to seat it firmly.
X Shark11 months ago
I looked around and could not find any Stainless Screen around town. But I did have some scrap .060 alum laying around. The first one I cut....I did it with a 3in holesaw not thinking that the slug would be undersize....So I had to redo it and cut it with a 3 1/4in holesaw. It was aprox .020 oversize and a sander cleaned that right up. I also added a 90deg fitting so ash would not fall directly into the venturi. Don't know if that was necessary? I'd been wanting to build one of these for a couple of years now. I laid out a criss cross pattern on 1/2in incerements and drilled holes all in it to Swiss cheese it. I have pix's but it will not let me post them.
bucklipe3 years ago
Very nice design!
How does the pipe stand up in the briquette starter?
Is the small black line on the ground the air supply to the generator?
Since the volume of smoke is low, do you think a coil of 1/4-1/2" copper tubing (say 10' ran through ice water for really cold smoke) could be substituted for the flex ducting? This would simplify the hookup from the pipe to the smoker.
rctys4 years ago
Alot like the Smoke Daddy which sells for $125+. Good design.
danneauxs4 years ago
This has inspired me. I've made several versions but have changed things up since I can't just walk into a store and get fence caps here. I've used a length of pipe "capped" on both ends with a coffee can. The bottom is fixed to the pipe with the air feed into it and the top one is removable to use as a cap. Fit the exhaust hose over that (drill some holes in the top first to let the smoke out) and you just remove the top coffee can to add more chips. I'ts cooler too. This is very cheap to make too. I guess I might post it once I solve a problem. The pipe was something I had laying around and can't find the same size cheaply. My local hardware store has some cheap but it's galvanized so I'm worried about contamination. Does anyone know if you could use galvanized pipe and coat it with something like grill paint? Would that have any effect. Especially, since my new design has a fitting on top (actually a galvanized stove pipe cap) and another air fitting and some copper line. You can then snake it into small side holes in a normal gas grill instead of smoker. Put a bottle over the end of the pipe and you end up with very strong liquid smoke! Oh thanks danneauxs
LVTurner4 years ago
Thanks very much for taking the time to detail this project.  I am going to add one of these to my UDS.  I watched another video and on a similar product and just knew that this was a simple project but what alluded me was what the materials were and the sources. I was searching for more hints and found your instructable.  I did want to know what volume air pump you would recommend. Is around 5,000 cc/min sufficient? Thanks again for sharing this.
lokbot4 years ago
This pretty nifty.  I ordered my pipe today.  I was wondering what kind of fitting would be used for an aquarium pump.
thingy5 years ago
Nice job. I like the portability this creates. Any chance we can get a clip of it in action?
Fast.Eddie (author)  thingy5 years ago
You're in luck! I'm smoking some spares today. I like to smoke thin and wispy over a long period of time, but I'll crank her up for the video and produce some serious smoke for demo purposes. Keep in mind that I don't try to cook with that volume of smoke! Believe me, you will love the immediate control you have over your smoke! Be warned, though, that the aluminum tube and the metal ducting get uncomfortably hot during the smoking process, so you will need oven mitts if you need to add more wood while it is still generating smoke. Let me figure out what to do with the video I just made and I will try to post it later today. Thanks for asking!
Try using double walled exhaust ducts to shield your hands from the heat generated in the smoking process and then vented through the aluminium ducts.  I installed one of those tankless hot water heaters, and the installation directions called for the double walled stainless steel exhaust ducts (I think they call it type "D", I'm not sure about that...anywayssss...) Instead of going out and buying the more expensive double walled ducts (or buying anything at all), I had some left over 3" & 4" ducts that I just put the 4" over the 3" and used spacers(washers) and self taping sheet metal screws to secure the ducts together and bingo double walled ducts at the best price in town, even at twice the price, its still the best price in town....for those who didn't get that joke...the price was FREE b/c it was left over material.....lol  Anywaysss I digress......Use that tip for the smoker or anything.....just  take it light....
--KB
DeadEye Ice5 years ago
I love the idea and most of the design, however i must question you logic on one point. you advise against coated pipes yet use galvanized fence caps whice contains zink / lead in the galvanizing? I would find a different way to cap the ends or wory of slowly giving my familt lead poisining or worse.
Fast.Eddie (author)  DeadEye Ice5 years ago
Umm...these are cast aluminum fence post caps. They also offer steel fence post caps. Use a magnet if you are unsure.
dbreece5 years ago
Great instructable! I'm in the process of building a smoker out of an old filing cabinet, and this looks like the perfect addition.

Just checking on the size of the pipe before I put an order in - is this the right size?

Nominal 3"
OD 3.5"
ID 3.068"
Fast.Eddie (author)  dbreece5 years ago
Yup, that's the one! But being the eternal cheapskate that I am, I saved a couple of bucks and bought the random length (10"-12"), which came in right at 12" on the nose. It will help to take the pipe with you when you go to find a fence post cap, if you can. I bought one cap that was made in China that was too big and had to be filed down, and another cap that was made in India that fit just right. I filed the Chinese-made one down until it fit real tight and then drove it in with a block of wood and a hammer, but then I broke it trying to take it out so I could take pictures! So I think it would be best to use a cap at the bottom that fits snugly enough that it won't fall out but loose enough so you can pry it out with a couple of screwdrivers if you need to for some unforeseen reason. I went to both Lowe's and Home Depot in my area and neither one of them carried fence post caps for 2 7/8" fence posts...they were all for 2 3/8" posts. Make sure that you have a fence post supply near you that you can get the larger caps from, or you might have to downsize the aluminum pipe...
johnboy685 years ago
This is the best instructable I have read yet and the first one I will do. Have a smoker that looks just like yours! I smoke a lot of deer jerky and have tried making my own bacon and have always had a tough time getting constant smoke at low temperatures. I was actually going to start looking for a "better" smoker but now I don't have to! Thanks for all the time you put into making this and sharing with the world (wide web).
Fast.Eddie (author)  johnboy685 years ago
Thanks so much for your kind words! I am so happy with the way this works I'm just looking for things to try...we smoked some sharp cheddar cheese the other day. It didn't noticeably raise the temperature in the smoker, but it was a warm (mid to upper 80s) day, so that might have had an impact. I was going to put some ice in the water pan if the temp went up but it didn't. I also came up with an "upgrade" of sorts...I was using the charcoal chimney to support the CSG and then disconnecting the CSG to use the chimney to start the charcoal for our Weber kettle. The air hose was taking a set and getting hard to disconnect from the air fitting at the bottom with my big clumsy hands, and I was worried that maybe the heat might melt the plastic part of the fitting at some point, so I replaced the fitting with a street elbow and a 3" pipe nipple to extend the air fitting out and away from the bottom of the CSG. The air fitting is now outside the perimeter of the chimney for easy access, and the chimney is now dedicated to supporting the CSG. We bought another chimney for lighting charcoal. BTW, I smoked the cheese for an hour, which turned out to be 'way too long...too smoky for our tastes (using hickory). I love oak wood and I should have used it, but hickory is so cheap and so plentiful in my area...
loppy965 years ago
this is cool
qballcat5 years ago
smokings bad mkay....lolz
Fast.Eddie (author)  qballcat5 years ago
Only if you inhale...
lol good call " I didnt inhale"- bill clinton after being charged with smoking pot...lol
strship475 years ago
Maybe something to try between BBQ's...turn off air suppy,put cherry or apple wood chunks in pipe,and put end cap in place.Fill the chimney starter with scrap wood and ignite.You now have the in-direct heat method of making charcoal.
Fast.Eddie (author)  strship475 years ago
Well, I think the charcoal produced would be minimal...I think it would take several full tubes of wood chunks to produce enough wood for a BBQ. I think you could produce charcoal more efficiently using other methods, primarily because the capacity of this project is too small for that application.
Yes I agree,I'm thinking more in terms of an experiment, since you already have the set-up in place.
pinkeyedjim5 years ago
I will probably try this. I've been trying to come up with a rig that I could use to cold smoke my own pork belly for bacon. This looks like it would do the trick quite nicely.
Fast.Eddie (author)  pinkeyedjim5 years ago
I sincerely do not think you will be disappointed. I don't know what the practical limit would be on how tall the smoke generator could be (taller = longer smoke times without refilling), and I have had no problems whatsoever with the wood chips/small chunks "feeding"...when I dump it out at the end of a smoking session, I usually get a very small amount of charred wood and an even smaller amount of ash powder as residue.
lenny255 years ago
Cool, so what have you smoked?
Fast.Eddie (author)  lenny255 years ago
I made a couple of test runs with no food in the smoker, then we smoked some Country Style ribs, and the following weekend we smoked some spare ribs. I'm still in the process of dialing it in, though. One of the really cool things that I like about this project is that both my wife and myself don't like a heavy smoke flavor...you know, the kind where you think you are belching smoke after eating dinner. I'm sure there is a scientific explanation for this, but we are able to fill the aluminum tube about 3/4 full with maple/apple/hickory and apple/hickory wood chips and chunks and we get a very nice hint of wood smoke. There is a significant amount of resin in the metal duct, so I think that maybe the harsh, volatile high temperature resins are condensing out as the smoke cools before it enters the smoker. Anyway, it definitely consumes more wood than I would ordinarily dare to use, but there is no hint of harshness in the food, just a subtle smoke flavor. And, while I am bending your ear, I decided to build this project after trying to smoke some jerky at 170 deg. I could get the temp down and maintain it, no problem, but trying to get wood to smoke reliably, long and slow, at that temp was next to impossible.
Pretty cool. I wonder if you could use this as a gassifier to run a small engine. You could just run it through a water bubbler (like a hookah) to knock out the smoke particulates but leave the hydrogen and carbon monoxide for the engine to burn up. Or do you think that higher temperatures would be needed for a gassifier. I'm not sure what you would use for the air supply. Maybe the positive crankcase ventilation tube?
Fast.Eddie (author)  discontinuuity5 years ago
It's a smoke generator. Please, don't stand too close to the smoke being generated. It can deprive your brain of the oxygen it needs to function.
btop Fast.Eddie5 years ago
Haha.
Fast.Eddie (author) 5 years ago


Ok, I've uploaded a short video showing the HCSG in operation...
rada1945 years ago
what does it do
Fast.Eddie (author)  rada1945 years ago
Well, you put your wood chips/small chunks in it with a well-lit briquette, turn on the aquarium air pump or other air source, and within about 10 or 15 minutes you will be producing clouds of smoke. You can control the amount of smoke by adjusting the amount of air...a very small amount of air for thin and wispy, more air for big billowing clouds. The smoke is cooled before it enters the smoker so you have the possibility of smoking at very low temperatures ("cold smoking").
It makes smoke, it's really pretty obvious.