Wednesday, 3 June 2009

V2 Wood Burning Stove

I decided to update my Stove design. The last wood burning stove did not allow enough air so the fire meaning that all the fuel and wind was perfect it took a bit too much faffing to light. I also wanted to allow myself to have a duel fuel set up and allow the stove to be a wind screen for a alcohol stove.

Trouser leg bag.





Size when packed, deodorant can for scale. Food can be packed inside billy can.


Grate and coat hanger pegs.


Wood burning mode.

Alcohol burning mode with grill higher.


This show the alcohol stove with the pot stand and tin backing tray wind shield. Useful to take for duel pot cooking if you really need to.


The billy can show holds 1 L easiley with plenty of room for stirring and bubbling

Monday, 6 April 2009

Homemade Stoves

This weekend I compared three stoves I built. One alcohol burning stove, one Hobob stove, and one wood gas stove. I did a sudo-scientific experiment on boil times of 0.5 of water. This is quite a lot of water, enough for two peoples worth of food, hence the seemingly slow boil times. All boil times where with lids off so I could see when a rolling boil was achieved, in real life I'd keep the lids on.

Wood burning stove



Boiled 0.5 L in 08:30 min.

Weight: ???

This used about a handful of wood to bring the water a rolling boil and it kept it there for a while (I did not time it).

The stove is made from a biscuit tin from Wilkinsons. From the photo you can see I had drilled line of holes around the base of the can. In the base of the can I used some mesh from a frying basket to hold the wood above the base to allow better air flow. I started off cutting the main hole with tin snips but ended up having to resort to a angle grinder and hence the hole ended up a bit bigger than I wanted. The billy can is held up with two lengths of coat hanger running across the stove. You can just make the ends poking out a little above the main hole

The stove lit easily and burned hot with limited smoke. I decided to allow the billy can to sit inside the top off the stove. The idea behind this was that it would reduce heat loss from wind and keep the billy securely in place. This did work well however as expected the stove could not draw very well and smoke and flames tend to lap out the front of the stove. This was easily resolved by drilling three holes 10 ish mm along the back of the stove just below the height of the base of the billy can. This meant smoke and flames where drawn out of the rear three holes. This did not work perfectly as the main hole was cut a little too high. If I make a mrk 2 I will make sure the top of the main hole is below the height of the rear exhaust holes.

Overall this stove worked very well. It was stable, reasonable boil time, easy to load fuel, easy to add fuel while cooking, stable. Bad points is weight, it is heavier than the soda can stove but it's still not that heavy, I need to weigh it to get a figure, this is countered by the fact that you don't need to carry fuel. The other down side is the size of it. It's quite bulky but could easily have items packed inside it.

A word of caution though. The work bench ended up quite scorch so in use make sure you use on sand, rocks or stand on some green wood, it may scorch it but it will not set fire to green wood. Placing it on peaty or thick scrub / woodland floor could cause a fire. Use responsibly.


Alcohol stove



Alcohol stove. Boiled 0.5 L in 09:45 min.

Weight: ????g

This stove was just a copy of the better soda can stove design. The pot stand is made from another wire coat hanger. The priming try was just a food can lid. This was the second design I tried. This was a pressurised stove, the first was a normal open one, but I did not like the idea of the fuel swishing around, this one has some loft insulation in it to help stop spillages.

This was fairly easy to make once I had stopped trying to scrounging cans from the curb side. I found Guinness are considerably thicker than other cans and would not stretch. I ended up using some cans from Sainsbury's, these have a nice high ridge like Pepsi cans.

The stove soon starts working and you can drop the penny into the center. I put about 4 cap fulls into the stove the first time and that was not quite enough to reach a rolling boil, 5 cap fulls and a bit was plenty with the boil continuing for some time.

I liked the fact that this stove was small and light. What I did not like as the fact that you could not add fuel during cooking. It would also need to have a windscreen in a real world situation. I think it would be ideal for a short trip and quick brew / noodles but having to judge fuel all the time would become awkward for anything other than noodles, tea e.t.c

Woodgas Stove

Photo to come

I did not actually boil any water with this stove as I had some problems with the pot stand which I did not have time to fix. The stove was constructed with two food cans. The inner can was a standard been can. The stove did burn very cleanly for a wood stove and looking down you could see the jets working burning the wood gas. In time I may go back and get this stove working properly however I am in no real hurry.

Why? Well although it seems like a good idea I am not convinced in that added complexity over the hobo stove. due to it's double wall construction you could not fit much wood in at a time. Also to add more fuel you would have to take your pot off put the wood in then put it back on, you can't judge how much fuel is left without constantly lifting the cooking pot. You also have to make sure you don't over fill the stove as that stops the jets working. I don't care about plack pots so a slightly cleaner burning stove does not bother me. This makes it all a little too much hassle over the hobo stove for me.

Conclusion

It should be clear that my favorite was the hobo stove for my type of cooking as I like to cook quite variable dishes not just noodles and coccus. I expect I will take the alcohol stove on short trips with a light weight windshield but take the hobo stove for anything over a night or two. I would consider taking both as the alcohol stove is so light and only taking a little methylated spirits for emergences or areas where using the hobo stove or fuel availability is difficult (unlikely in the UK). The wood gas stove as mentioned above still needs some works but as I said being as the hobo stove does not need much fuel any added efficiency does not make up for the disadvantages posted above. I need to do some more tests actually out camping and I'll update as more info comes to light.

Sunday, 8 February 2009