Gas Bottle Hot Smoker

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Introduction: Gas Bottle Hot Smoker

Metal Contest 2017

Runner Up in the
Metal Contest 2017

For several years I have wanted a large (by British standards) hot smoker. High prices put me off but and in the end I decided the only way I was going to afford one was to make my own. I opted to make mine out of a couple of old gas bottles.

Neither myself or my friends who helped are professional welders but with a little time we managed to come up with some thing pretty solid.

Edit: I have since been informed that using gas bottles may not be legal in some countries, as they remain the property of the gas supplier. If you are in such a location another option would be to use the air receiver off an old compressor or some other suitable tank.

Step 1: Removing the Valve

By far the hardest part of building the smoker is getting the valve out of the gas bottle. Before attempting to remove the valve, I made sure all the gas had been used up and then left the valve open outside for a couple of days. You may be lucky and be able to getaway with a pipe wrench, this did not work for me and ended up rounding off the valve nut. Some definitely come out easier than others, in this casein the end I had to resort to building a large box spanner with a 6 foot cheater bar to unscrew it whilst it was attached to a work bench with ratchet straps to stop it spinning.

Step 2: Ensuring There Is No Gas Left in the Bottle

Once you have the valve removed, fill the cylinder with water to displace any remaining gas. To ensure all the gas is displaced and no bubbles were remaining I emptied and re filled the tank three times. As the tank full of water is very heavy I syphoned the water out between fills to make life easier.

Step 3: Cutting Opening for Flue

The next stage is to cut the necessary opening for the flue and two join the two bottles together. I used a holesaw. To keep it centred with valve holes I turned a bushing to guide the pilot bit. Drilling the hole was really tough going as a holesaw that large has a tendency to snatch. If I was to make another I would most likely cut it with a plasma cutter or if one was not available a jigsaw.

Step 4: Cutting the Door Openings

As I have a plasma cutter I used it to cut the door openings. For the cuts along the length I used angle iron as a guide for the ends a strip of steel, held in place by a ratchet strap. If you don't have access to a plasma cutter you could cut the opening with an angle grinder or maybe a jigsaw with a suitable blade.

Step 5: Creating the Flue Regulator

We need a way of regulating the air / smoke flow through the smoker. We came up with the idea of a pair of plates with triangular holes. One welded to the chimney and one to a short pipe attached to the top of the main smoke chamber. They rotate around a bolt which causes the holes to either align or not. We added a cowl from a narrow boat fire but unless you intend to smoke in the rain this is just for appearance.

As I was having some laser cutting done for another project I opted to have these laser cut at the same time, along with the grills, which can also be seen in the picture. These could of course of been fabricated from bar stock instead.

We also created a similar regulator mounted to the smoke box door to control the amount of air getting to the fire.

Step 6: Welding the Smoke Box & Firebox Together

I added a small length of 125mm steel pipe between the fire box and the smoker main chamber. This along with a raise baffle help stop flames reaching the smoke box but my main reason was to give enough space to fit my Mig torch.

Step 7: Hanging the Doors

We welded a 35mm steel strip around the edge of each door so that when closed it overlaps the edge providing a sealing surface. We had intended to add a gasket to help seal the smoke box but this proved unnecessary, although as I had already purchased it I may add it in the future.

The hinges were simply fabricated from steel bar drilled to accept a bolt as the hinge pin. They were welded to the steel strip and the body of the smoker. The door latches were fabricated and of a simple leaver design once again made of bits and pieces from the scrap bin.

One improvement I will probably make in the in the future would be some form of insulation on the handle as it gets rather hot in use. Perhaps using the handle of a spring handled welders chipping hammer.

Step 8: Removal of Old Paint

As I intend the smoker to live outside year round it required painting. Due to the heat produced during operation the existing paint all had to be removed prior. I did this with a combination of an angle grinder fitted with a flap disc and a random orbit sander.

Step 9: Finishing Touches

I welded small pieces of angle iron 120 degrees apart to support the grills. I added enough to support up to four grills in the smoke box and one in the firebox to act as a grate. Prior to painting I lightly sanded and degreased the smoker with paint thinner. If you are going to paint your smoke you will need to use a high temperature paint. I chose to only paint the exterior and used one formulated for BBQ's and its seems to of held up well.

Step 10: It in Use

So far I have only had chance to us it a few times, but I am calling it a successful project. It only takes a very small fire and it seems to last for ages which is good. A few lessons I learnt early on are as follows

  1. Put a tray in the bottom raise up, to stop fat dripping onto the fire.
  2. As you would expect its hotter at the bottom than the top, so you need to take it into account when cooking many of the same thing.
  3. The handle get really hot!
  4. It might be worth making a wider base to improve stability, although I am yet to have any issues.

All in all very happy with it and I am looking forward to the summer so I can use it again!

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    28 Comments

    nice work with the bottles, and you got 6 birds in there! wow!

    So did you rotate them? I see the upper level flock is still a bit rare there.

    how did they make out? anyway great action shots! but I'm most impressed with all the views you generated already, how do you do that?

    check out my smoker build on Instructables called The Dragon Unifire Smoker

    20161202_172126_LLS.jpg

    Actually there are three per shelf, although its a tight fit. I swapped them around a couple of time during the cooking. Everything I have cooked in it so far has worked really good. Not really sure how it got so may views, luck of the draw I guess.

    Your project is really good, excellent instrucable!

    Thanks, good luck in the contest

    Excellent looking smoker! I agree with others about doing something to widen the base, though - it looks tippy to me, like a stiff breeze could knock it over. Three pieces of rebar welded 120 degrees apart on the bottom would work great; if you "L" shaped them (pointing down), they could anchor into the ground.

    Regarding personal protection: I once learned the hard way about not wearing proper equipment while using a right-angle grinder once. I didn't lose any fingers or eyes, but that was only luck. As it was, I have some gnarly scarring on one knuckle to show for it.

    Gloves and eye-protection - always - from now on! Ideally, goggles and a face shield, plus closed toe shoes.

    For the plasma cutter - you're alright there; some simple leather gloves might be called for, mainly for when you forget that what you're doing is hot, and you go to pick up that piece you just cut (ask me how I know). I typically like to wear a single glove on my non-torch/stinger/gun hand, because a bare hand on the other gives better control of the trigger (though sparks can sting of course).

    The black shirt is perfect (never wear white when using a plasma torch or arc welder - the UV from the arc can reflect up and under your helmet - welder's eye ain't fun!).

    Finally - I'm curious: When I think "British Cooking" - bbq/smoker isn't at the top of the list. I know that smoking is an old meat preservation and cooking technique, but is it become more popular over there? I mean, here in the States, it's crazy popular among a lot of people.

    Can you get a good pork shoulder or a nice brisket over there for a long smoke? Have you done any ribs?

    Also - if you like it - try a smoked pork belly. Get an uncured one, and just season it up and smoke it for a few hours (usually a full belly will only take 3 hours or so). Or - if you like "American" bacon, use some curing salt and do a cure on it (this takes a long while in your fridge), then pull it, smoke it, then cut it up and enjoy some really crazy nice bacon.

    Dang - I'm makin' myself hungry over here, and I've already had dinner!

    Thanks for your response, I think you put as much effort into writing it as I did the Instructable. A good shoulder barge and it just rocks slightly, I think I might however make a cart for it to improve portability with will as a by product improve the stability.

    All the safety advice is duly noted, I am normally much better at remembering to use PPE and of course not wearing it in the pictures does set a bad example.

    BBQ and smoking has become pretty popular of recent years, although I do go to further lengths than most people I know. We are lucky in the UK that there are plenty of proper butchers shops around so getting any cut of meat is not a problem. Although we ofter have different names for them.

    I have done smoked pork belly a couple of time, one of my farvoites but not good for the waist line! I'm keen to have a go at some salt cures, so might have a go at making my own bacon some time soon.

    Cheers

    If you do pursue curing pork belly for bacon, you have to use "pink curing salt". It's not normal salt - it's a special nitrate-loaded salt specifically for curing meat (it's what ultimately makes cured meat products "pink"):

    https://en.wikipedia.org/wiki/Curing_salt

    You're lucky to have butcher shops. Here where I live (Phoenix, Arizona), if you want something "slightly different" than what you can get at the grocery story, you have to either hit up one of the very few specialty butcher shops that are around (my go-to is a place called "Hobe Meats"), or you have to visit an ethnic market shop (we have quite a few Asian and Mexican grocery stores around). Another option is to hit up a "carniceria", which is essentially a Mexican butcher shop.

    While we typically have a great selection of meat cuts to choose from at grocery stores, certain things are more difficult to get (like pork bellies, as well as old-time well-marbled pork chops). I've found for pork bellies, though, can be easily purchased at Costco - and they also carry larger cuts as well (full tenderloins, full briskets, etc), that are typically harder to find at most grocery stores.

    I am surprised that your smoker is as stable as you note - it certainly doesn't look that way from the pictures, so I'll take your word!

    Even if you remove the painted cylinder photo it should probably be enough

    I have to point out that what you did is ILLEGAL in the UK and by publishing this you have incriminated yourself.

    https://www.calor.co.uk/news/illegal-handlingscrapping-of-calor-gas-cylinders/

    I was unaware of this, and have amend the listing to suggest other alternatives.

    I thought you should know as I have posted this to other people who wanted to do the same or similar. Not many people know about it and I only found out when I contacted a gas cylinder company about obtaining one.