Tag Archives: build your own

Schmokin’ (part 3)

[Part 3 of a series about designing and building my own cold smoker. Part 1 is here, part 2 is here.]

4. Ventilation

Fire needs air to burn; and the smoke needs to escape so it doesn’t choke the fire. So you need a hole to let air in, near the burner, and a hole to let smoke out, near the top of the chamber. In my case I just drilled a bunch of small holes. At first I found I hadn’t drilled enough, as the sawdust kept going out. In the end I drilled about 90 5mm holes (no special reason for the size – that’s just the biggest suitable drill bit I have) for each. I based the number on another smoker design I found on the web – which had much larger holes but fewer of them. If you’re going to do it, and you happen to be using a different sized drill bit, or perhaps cutting a single hole, then I’d advise using a little maths to make sure you’re getting a similar overall amount of ventilation, as there’s nothing more frustrating than trying to light your smoker only to find it keeps going out.

When I tried my first smoking run there were about a fifth of the holes there are now. Fire needs air!

When I tried my first smoking run there were about a fifth of the holes there are now. Fire needs air!

It’s nice to be able to control the exact level of ventilation, as this enables you to control temperature and burn speed. I fitted a couple of pieces of spare hardboard which I could use to cover some or all of the holes.

5. Where to store the food

You have a number of options for how to store the food in the smoker. Traditionally you’d hang meat or fish from hooks. I did consider fitting a couple of bars, like you’d get in a wardrobe, and hanging the meat off those with butcher’s string. But in the end that seemed like a comparatively labour-intense option (and not suitable for cheese and other non-meat products) compared to a shelf.

You don’t want one side of your food up against a solid surface, because the smoke won’t reach the food on that side. That’s easily solvable by using a rack. You can either make your shelf out of, say, an old oven shelf (if that happens to fit nicely in your smoker) or you can do what I did and put in a solid shelf and sit the rack on top of that. We had a bunch of roasting and grilling racks lying around, so I just used those.

The shelves in the original unit were a bit too small, and the ridges at the back would have got in the way.

The shelves in the original unit were a bit too small, and the ridges at the back would have got in the way.

I was intending to sit the units upright, and use the shelves originally intended for baked beans and whatnot to sit the food on while it smoked. But (a) the shelves were a bit narrow and the gaps between rather small, and (b) at each level the cupboard had vertical dividers designed to stop things slipping down the back of the cabinet, and to run screws through to fix the unit to the wall, but which in our smoker would just get in the way and prevent larger items from straddling the two wall units. So at Becky’s suggestion, I turned the unit so that one of the doors was facing upward (the other door facing down of course, as the original kitchen units were now back-to-back), and cut some hardboard shelves, which sit on top of the ridge between the two units. I added a couple of stronger bits of wood to act as beams providing extra support to the shelves.

This is a top-down view of the smoking chamber. I used a couple of spare bits of wood as beams to support the hardboard shelf (which is not shown in this picture)

This is a top-down view of the smoking chamber. I used a couple of spare bits of wood as beams to support the hardboard shelf (which is not shown in this picture)

6. Spreading the smoke

To judge by smoker designs I’ve seen in books and online, this is an optional extra. But it seems important enough to mention. Simply put, if you just have your smoking fuel sat under some meat, at any given moment the smoke will be arising from a fairly small area of the burner. It will waft upwards and, most likely, strike a fairly small area of the smoking chamber. You’ll end up with some of your food getting the full force of the smoke, while the rest maybe doesn’t get any smoke at all.

The solution is pretty simple: you put a barrier between the fuel and the smoking chamber, with lots of holes in it through which the smoke can seep. Rather like the way a shower head spreads water which would otherwise come out in a single jet, this spreads out the smoke.

The shelves have dozens of holes drilled so the smoke spreads out.

The shelves have dozens of holes drilled so the smoke spreads out.

For our smoker, I simply drilled a bunch of holes in the shelves. Since the shelves more or less completely covered the gap between the burning chamber and the smoking chamber, this prevented the smoke from just going straight up, and instead spread it around nicely.

7. Thermometers

Getting a thermometer for a smoker is surprisingly difficult. Well, to be fair – not difficult at all, if you know where to look. I’m going to shortcut that process for you.

You can get lots of different kinds of thermometers. Meat thermometers, medical thermometers, oven thermometers, fridge thermometers. All of these have problems with them of one kind or another. Wrong temperature range (cold smoking is about 10 C to 32 C, with the ideal temperature in the mid-20s); not for measuring air temperature; can’t be read without opening the smoker and dispersing the smoke. But as it turns out, there is a thermometer that works perfectly, and is quite cheap.

Surprisingly, the one I ended up getting is a terrarium thermometer, for reptile houses. It has a probe with a longish cable so you can measure the inside of the smoker without opening it up, a digital readout that will do Fahrenheit or Centigrade, and measures a range of temperatures from -20C to 110C. Best of all, it cost less than £10. Here’s a link to the one I bought.

Best. Thermometer. Evar.

Best. Thermometer. Evar.

8. Other stuff

If you’ve done the above, you’ve got a working smoker. But there’s a few little nice-to-have things that you might want to consider.

First, where to put your smoker. It’s going to leak smoke over the course of many hours, so you probably don’t want it in the house. It has holes in the top, so you don’t want anywhere it’ll be exposed to rain. But you want at least a little ventilation so there’s fresh air to keep it burning. I’d also suggest somewhere with a bit of spare room for when you’re juggling trays of meat, gas rings, matches and so forth; and somewhere with a light so you don’t have to add a torch to that list, as you may find yourself refuelling after dark.

Second, consider adding a viewing port, or better yet a door big enough to slide the burning tray in and out. In the early days you’ll find yourself frequently wanting to check if the fuel has gone out, and you don’t want this to be difficult or to lose you a load of smoke. To access ours you have to open the lid, remove one of the two shelves, push aside two beams and then reach right to the bottom of the smoker. The only way to view the burning tray without following a similar process is to attempt to shine a torchlight through the ventilation holes while simultaneously looking through the self-same holes. Needless to say I’m already thinking about how to fit a viewing port to save me all this hassle.

Schmokin’ (Part 2)

[Part 2 of a series about designing and building my own cold smoker. Part 1 is here, part 3 is here.]

3. The smoking chamber

There are designs all over the internet and in various self-sufficiency books for creating your own smoker. I’ve seen designs based on converting an old oil drum, a filing cabinet, or building one out of brick. Our house is full of old odds and sods that might be usable. It has a defunct outdoor toilet which would probably do a great job. But we decided to go a bit smaller this time, and use an old metal kitchen cabinet that we had sitting out in our garage.

The cabinets just before I started drilling holes in them.

The cabinets just before I started drilling holes in them. Still quite dirty from our garage.

The basic requirement is something big enough to hold your burner and your food, air-tight enough that all the smoke doesn’t blow away, and capable of being fitted with ventilation holes and shelves or hooks or whatever you are going to use to support the food. It’s pretty common to divide the smoker into two parts, one where the burning happens and one where the smoking happens, either separated by a divider or perhaps even in two separate units connected by a tube that carries the smoke.

You might be wondering if another requirement is that the chamber not be flammable. Well, no. The burning tray (see part 1) definitely should meet that requirement, but as the fuel is only smouldering there isn’t any flame or sparks that could start a fire. You can buy cold smokers over the internet that are actually made from cardboard. So this is not a particularly important criterion (though probably a nice to have just for peace of mind).

In our case I wanted to keep it simple. We had two halves of a kitchen wall cupboard. The plan was to sit the burner in the bottom, and put the food on the shelves above, though as explained later, in practice I ended up standing it on its back, with one door facing towards the sky, and fitting a shelf in the new orientation. But, same principle.

The back of the cupboard was open (because the designer assumed it would be up against a wall) and one side of each unit also open (because the designer assumed they would be sat side-by-side). I put the cupboard units back to back, eliminating the problem of the open back, and then screwed a piece of hardboard to the open sides to make a completely contained unit.

There is no escape from this smoker. Except, you know, the door.

There is no escape from this smoker. Except, you know, the door.

I used decorator’s caulk to seal the gaps between the two units, to ensure that minimal smoke escaped from the unit (except via the ventilation holes at the top). I later read that a lot of smokers aren’t exactly air-tight and will have smoke leaking out a bit. So maybe that wasn’t necessary. But I can only imagine that it increases the tendency of the smoke to go where you want it, i.e. into the smoking chamber and then out the top, rather than just spreading out in all directions.

With that, the basic shell of the smoker was ready. In the next post I’ll talk about ventilation, where to put the food, spreading the smoke, thermometers, and a few other little things that make life easier.

Schmokin’

[This is part 1 of a series about designing and building my own cold smoker. Part 2 is here, Part 3 is here.]

Becky and I have talked about smoking our own food for some time and I’ve finally got around to making our words into reality and built our own cold smoker. It took a fair bit of research and a modicum of DIY skill but I’m going to attempt to boil it down into easy steps if any of our readers fancy giving it a go.

For the uneducated, the difference between cold smoking and hot smoking is that with cold smoking the fuel is merely smouldering, generating smoke but not (much) heat, so the food just gets smoky but doesn’t cook, while in a hot smoker the food is cooking as well as being smoked. Since we wanted to smoke our own bacon and ham for cooking later on, the cold smoker was the obvious choice for us.

Can you believe we were able to resist the urge to eat this long enough to smoke it?

Can you believe we were able to resist the urge to eat this long enough to smoke it?

The basic requirements for a cold smoker are:

1. Something to burn sawdust in (and of course, some sawdust)

2. Something to light the fuel

3. Something to contain the smoke and the food you’re smoking

4. Ventilation (a way for air to come in and a way for smoke to get out)

5. Something to sit the food on or hang it off

6. Something to spread the smoke evenly around the smoking chamber (though from what I can tell this is an optional nice-to-have)

7. A thermometer, so you can make sure you’re not inadvertantly hot-smoking your food.

1. The burner and the fuel

For cold smoking, you need fairly fine woodchip, so that it can smoulder but not burn. I’m told that you can use shavings from a wood plane, but so far haven’t tried this. At the moment we’re using specially made sawdust, which is very fine indeed – dust and very tiny shreds of wood – which we purchased online. I’ll be trying the wood plane approach in due course and will report back how that goes.

You should give some thought to what kind of wood you want. Different woods work best with different foods. I won’t cover this in detail here as it’s easily available elsewhere, but I understand that oak is a very versatile wood – we used it for our bacon – and applewood goes well with cheese and ham, so that’s what we used for those. But there are dozens of usable wood-types, with subtley different flavours. One thing to avoid if you are producing your own woodchip is resinous wood, like pine – I do not know why, but it is not appropriate for smoking.

I found burning the wood a bit more challenging than I’d hoped. Don’t get me wrong – I succeeded in getting a 24-hour burn without the smoke going out, which is basically good enough to smoke more-or-less anything. But there were various things about it which weren’t quite satisfactory, as I’ll describe below.

My research indicated that you can burn the sawdust in pretty much any metal container. I’d heard of people using tin cans, specially designed shop-bought mesh trays (about £50 for a large one), or a metal tray such as an old roasting tin. This last approach is what I’ve used.

The simplest configuration is to put your sawdust in a heap and set light to it in one corner. The smouldering, burning section of the sawdust will gradually pass through the heap and generate smoke as it goes. However this is obviously a bit less controlled than you ideally want.

I have heard of people using a cylindrical burner, filled with sawdust which is then lit at the top and burns downward, like a candle. That’s one way to control your burn, but obviously not open to those of us using a roasting tin! Instead, I decided to try and copy burners I had seen online which arranged the sawdust into a long thin line, like a fuse, which then zig-zagged back and forth across the burner, separated by little walls to stop the burn spreading out of control.

My attempts to do this met with mixed success. The simplest arrangement, which saw me heap the sawdust against three walls of the roasting tin, forming a U-shaped fuse (no walls) worked well in that it burned steadily, did not tend to go out, and produced temperatures between 15 and 25 C, which is about right. However it was very fuel-hungry, getting through a full kilogram of sawdust to produce 24 hours of smoke.

 

The simple U-shaped fuse.

The simple U-shaped fuse.

The alternative approach, which was to build walls out of tin foil and then use these to create a zig-zag channel, enabled me to put much more sawdust in the tin (because the walls meant I could put the lines of sawdust much closer together without risk of the fire spreading between them). However, I struggled to keep the sawdust alight. I tried several configurations and each time the smoke would stop, sometimes after a few minutes, sometimes a few hours. But never long enough to give me confidence that it would keep burning through the night, which is what I was aiming for.

The zig-zag approach.

The zig-zag approach.

The bottom line is that I think I can do better than 1kg per 24-hour burn; the shop-bought burners manage 16 hours with 300g, so my U-shaped arrangement is terribly inefficient. But my attempts to improve on this have been pretty much unsuccessful. I have ideas involving using a mesh for the walls so air can flow more freely, or perhaps copying the cylindrical design mentioned in the link above. Watch this space.

2. Lighting the fuel

I did quite a bit of research before this project, and found a lot of differing advice on how to light your sawdust. A lot of people were talking about using a tea-light to get it started; that presumably works for shop-bought burners, which are made of a mesh through which the tea-light flame can easily pass, but it didn’t work for me at all. Another approach is to use a blow-torch, which seems to work fine. But in the end I settled on using a camping gas ring. I placed one corner of the burning tray over the gas ring, and after about 5 minutes on a low heat, the sawdust was blackened, smoking and sometimes even aflame (when it’s on fire, that’s definitely the time to stop, but ideally a bit before that). The gas ring has the advantage of being fairly stable and easy to just switch on and off, and it gets the tray nice and hot which I imagine helps to keep it alight at the start.

I saw some people talking about using methylated spirit to start the process off. I’m sure that makes it a bit easier, but I did not find it necessary at all, and as it’s one extra layer of hassle, I wouldn’t bother.

Next up: the smoking chamber.