Two smaller tins, of the same size one inverted on top of the other, with a strip of tin say 3" wide around the join holding it all together.

A couple of paperclips in holes would be enough to hold the strip in place, the top half would then fit neatly in the sleeve.

Might give that a go ......

Thanks for the idea.

HI.

I made a little modification to the general idea of the large can oven.

I took one large can and one slightly smaller can and put it inside the larger one . I put one layer of aluminum foil around the outside of the smaller can

I then put metal spacers at the bottom of the larger can, between the larger and smaller can which made a space 1 to 1.5 inch high ( your choice) above the bottom of the can.

I then placed (non flamable) fibergalss pink insulation
between the inner and outer can.

The reasons for the spacers is to make certain that the fiberglass insulation does not burn. As the bottom of the cans are in direct contact with the flames.

I also put aluminum foil on the inside of the can lids.
Then adjusted the vent holes to accomodate the new design.

This realy does not add much in weight. However it certianly improves the performence of the oven.

The aluminum foil on the smaller can ( reflective side inwards) is a vapour barrier, and protection for the insulation.

Basicaly this modification turn the oven into the same design as you Home's electric oven/range.

Enjoy.

yt

Northernflame

Hi Stuart,
I'd go for an old paint tin - they tend to be roughly the size you are looking for. Obviously you'll have to take care to clean out the previous contents lest your pizza tastes of matt magnolia emulsion. Personally I'd steer well clear of an old oil-based paint container simply because of the difficulties in removing all traces of paint. If you are prepared to consider using new materials rather than recycling something previously used I'd be tempted to visit a heating and ventilation supplier. They will have available lengths of stainless steel tubing of relatively thin wall and large diameter in lengths up to 4 metres or so. You should be able to get quite a tall loaf in such an oven or several dozen thick crust pizzas! They will have end caps for you to use as base and lid. Should you go for a paint tin please DON'T bake with the lid firmly in position. The seals on paint itns are very effective and you really do need to let the hot (expanding) gas out!

Hope this helps - I'd like to know the outcome before I risk my own health!

Colin.

I did once have a look around a DIY shed (in the UK) and most of the suitably large paint tins were in fact plastic.

I take the point aboutthe tight lids, I have seen a cake storage tin in stainless steel that even had a clear glass top. For it to be effective as a cake storage tin it had a very tight fitting lid. From trying out smaller tins, the lid needs to be removed easily so that you can check whats going on inside.

Interesting comment about the stainless tube, I did not think of that because most of the heating pipes you see in the UK are the corrugated flexible stuff used in big rolls.

Hi Stuart,
I'm in the UK too - in Hertfordshire. The tubing I have in mind is not the flexible type as per kitchen extract but rigid as per central heating 'boiler' flue. I doubt the B&Q-type sheds would stock what I have in mind - you'll need a more specialist supplier. As far as paint tins are concerned it would be a matter of locating one in someones' garage - if ever I get to the back of mine I'm sure I have such an item for you. Our paint suppliers have all changed over to plastic, as you point out.
And I'd still rather you tried it first!
Colin.

Hi folks
Try your local Autopaint for empty metal paint cans with bail handles - may not have very big sizes, but I have bought 2.5 litre ones off them.

Bread baking. In a bread machine, and when you bake bread in an oven in a tin, there is no air circulation at all around the loaf, except for the top surface. Generally, you do need a high temperature, in the region of 200 Celsius or more

Mike

There is a specialist plumbing and heating place not far from me, I will take a walk in the morning and see what I can find. If they aint got it they ought to know where to get it.

I am just off into town to get a thermometer to poke in a tin (which is OK for 9" pizza) so I can see how hot it gets inside on various stoves.

Thanks.

I cut a hole in the bottom of an old chocies tin and fitted a baffle plate inside. A 96L had just the right flame pattern and generated enough heat to drive the tin temp inside the tin up to circa 240C, indoor conditions.

I thus cooked my first kerosene powered chip butty (fries sandwich to some of you), see here;



However the chips, but not the bread, aquired a definite taste from the kerosene fumes, not good.

So I modified the tin to have a solid bottom again. No kero fumes in the oven now but the temp would not rise above 190C, and only about 140C outdoors.

Insulation must help and I have in mind making a internal skin out of another tin and insulating the gap with loft insulation. To test what the effect of insulation would be I made a foil and loft insulation sandwich on the sides. This made a small differance, the oven went up to about 220C. I then added a similar insulator to the top, the effect was dramatic, in 5 mins the temp shot up to about 400C off the scale on my temp gauge.

You dont need an oven anything like that hot of course, but it appears that if you make an insulated tin you could have a bigger oven (if you can find the tin) and use a smaller stove such as a 96L turned down low. And running the oven in the draughty outdoors wont make so much differance.

Your tin appears to be about the same size as the one I used in my "big" oven, though perhaps just a bit shorter.

I had no problem heating mine to over 250 degC (495 degF), on a sub-freezing day with a bit of a wind, on an alcohol burner.

Here's the original thread, the big oven is about 1/2 way down:

http://www.network54.com/Hide/Forum/thread?forumid=81021&messageid=1073513254

Briefly, I adapted my design from one in a camping book, wherein the author insisted that one of the secrets to making a camp oven work is convection. If you look carefully at mine, you'll notice 2 rows of vent holes on the sides, one at the top edge and one at the bottom edge. These serve to supply the necessary convection, which I believe is why I've had such good luck with mine.

I've also discovered that preheating thoroughly is important; if I don't, the introduction of the cold food into the oven makes it devilishly difficult to bring to temperature.

Hope this helps.

I can see that the convection holes will make the oven work better as an oven, more even temperature distribution etc. But I dont see why the convection holes would make the oven temperature higher.

Outdoors, in an air temp of around 12C and using my 96L kerosene burner (which I suspect might be a bit more powerful than an alcohol burner) I could only get the temp of the oven up to 140C.

I had 6 small holes in the lid of my tin, I think I will seal them, put them on the side and see what happens.

Hello,
Great thread with lots of experiments. The reason for the holes on the side (top and bottom) is to create a convection. Holes in the top will just create a hot air exhust. You need the air to circulate rapidly. The heat will build up at the top while being sucked in from the bottom and bled off from the top. In a nut shell, the hot air will keep moving upwards only to hit the top and be vented out the side keeping an even operating temp throughout the oven.
Grant is using one of those Landers, Frary and Clark (spelling?) stoves. From what I have read they are quite powerful. Nut the soda can or trangia type of stove.

Chuck

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=2392042746&category=20632&sspagename=STRK%3AMEBWA%3AIT&rd=1

Rik

Seen something simular before, a double stacking pan set with a glass lid.

I suspect however I would still get the same problem, the heat losses would be too great for a small stove to cope with. And besides the tin oven only weighs about 450g.

The simple tin when insulated is a lot better, and the 96L will drive it. What I need now is to get hold of a second tin and make a simple insulated wall and lid.

I have been trying various options in my quest to make a oven for backpacking powered by a small stove, such as a 96L.

Oven chips (fries) are a good test food, they need a fairly hot oven to go crispy, and you can check for even heat distribution, there cheap as well.

Fuel.
The hole in the bottom tin of stove is more efficient, but kerosene appears to give a taste to some types of foods, particullay chips (fries). BBQ lighter fuel (as sold in the UK) is much better in this respect, undestandable I supose, they remove the smelly bits from BBQ fuel to prevent it tasting BBQ food.

Hole in bottom.
Once the fuel tasting problem is solved, this design allows the internal temp to go far higher for a given stove power. The non-hole in bottom oven is far simpler to make of course.

The hole needs to be fairly big to ensure all the hot air from the burner goes into the oven, I used a 115mm hole for my 96L.

Convection holes.
In a small oven if you put the top convection holes in the sides of the tin, it appears that a cloud of low temp steam forms over the food and is trapped in place. The tops of chips stay soggy. If the convection holes are in the centre of the top of the lid, this draws hot air over the top of the food and the chips in the centre go crispier.

Insulation
Makes a massive differance, a simple foil blanket and roof insulation sandwich will add 50-80c to the temperature. Insulated sides alone make little diferance, but add an insulated top and the temp inside soars.

Baffle.
On the hole in bottom of tin oven, you need a baffle to protect the food inside from the direct flame. The spacing of the baffle from the bottom is important. If the spacing is large, say 3cm, the stove wont burn cleanly when high. Its as if the stove cant pull oxygen in from the surrounding air and you get an incomplete burn and more fumes. If the baffle spacing is 1cm or so this effect is much reduced.

Insulated baffle.
A simple baffle causes a lot of radiated heat into the bottom of the food (the bottom of the chips get burnt). In a tall oven this would be les of a problem. I have experimented with a double baffle, two sheets of tin about 5mm apart and this does reduce burning on the bottom of the food.

I also suspect that a larger baffle, to say within 15mm of the wall of the oven will direct more of the hot air up the sides and over the top of the food.

Using a hole in the bottom type tin oven, I cooked 3 lots of chips (fries). I used 3 fuels, white spirit (UK), BBQ lighter fuel (UK) and paraffin.

In a blind tasting two people both chose the chips cooked with BBQ lighter fuel as having the least 'fuel' taste.

Paraffin was the worst, decribed as 'awfull'

If your prepared to carry a coleman oven, why not get a British Army Mk2 petrol cooker, I have one and they throw out a massive amount of heat, or for more even heat, try a twin burner No3

http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=3671231584&category=16036

Rik

sorry to endlessly prolong this oven thread-but of the two solutions : more output v lagging - your average scout might have something to contribute to the latter. it is perfectly possible to make a working oven out of a cardboard box lined with tin foil and perched carefully over a heat source eg charcoal. Ive done the same over a roarer with excellent results. I too have a coleman which struggles to keep up a reasonable temp. without resorting to my oxyacetyline gear! So I solved it by finding a box minus one side lining it with thick tin foil ( Lakeland Plastics sell the best) and putting over the Coleman-no problems so far( and plenty of well cooked food) mike

Whilst they look powerful, they are a bit big and I aint too keen on using petrol stoves for 'domestic' camping.

Interesting idea, did not think of using a cardboard box. Might give it a go.

I did use the oven when I was camping last week.

With a paraffin burner running on BBQ lighter fuel and a foil hat to the oven it achieved a respectable 240C and cooked my pizza just fine in 15mins.