Intro: Woodburning Stove From Sheet Steel
This is a guide for how I made my stove. It is not the only way.
I am not a professional metalworker but a guy with some tools and a workshop .The final outcome was very successful and I have received many positive comments about it.
The flat top gets hot enough to cook on and/or boil a kettle and the output it approximately 4-5kw when it's fully up to temperature. Perfect for heating a small room. I've only ever used it when camping outdoors or in my yard but the plan is to use it when winter camping in a bell tent.
I am making this Instructable to show people how easy it is.
Almost everything was fabricated from the sheet steel for this (apart from the flue pipe which I bought in especially) and the whole process took me about 10 hours in total spread over a few evenings.
Tools and Equipment needed:
- Sheet of mild steel. I recommend at least 3mm (1/8th) steel and no thicker than 6mm (1/4) unless you have industrial machinery.
I used a sheet of 4mm mild steel 1200mm x 625mm that I had lying around so based my design on that but what ever you have access to. I guess you could use thinner but my stove holds its heat really nicely and doesn't deform with heat so I wouldn't want to make it any thinner.
- Angle Grinder is your friend.!
I got quite good with an angle grinder doing this project and its a brilliant tool if used carefully.
- Jigsaw Puzzle!
A good quality jigsaw is a great purchase as it needs a bit of grunt to cut through the steel - and always good quality blades, even if your machine is cheap, spend the money on good blades. Cheap blades are a false economy. I have a Bosch GST 150 230v jigsaw and only ever buy bosch blades.
- File - good quality large flat file for taking off burrs and a round or half round for internal curves are essential.
- Emery paper / Glass paper - get fabric backed for metal as it lasts a million times longer.
- Perseverance! - most important tool - metalwork requires a lot of manual labour. Especially this method as I am not using a plasma cutter or any industrial machinery to cut my steel. When I started I didn't quite realise how much effort it was going to take and how heavy the finished stove would be!
Step 1: Step 1: Design
So I designed my stove on Google SketchUp. I love this software and it is amazingly easy to use, even for a novice. Everybody should have it and best of all, its free!
To start with I drew the whole stove then calculated how big I could make it.
I already had a sheet of 4mm mild steel that was 1200mm x 625mm so I made it as big as I could out of that.
My plan was to make the front, sides and back like a 'net' of a cube and 'fold' them in to create nice smooth corners, rather than weld the plates together and have to spend hours grinding away to get a good finish.
I would then seam weld the top on and fit a baffle inside to improve the burn (see 4th image) and then fit a bottom with bolts so it is removable for cleaning
For the legs I originally planned on using some more sheet steel and making some little angled legs that could bolt on but I ran out of steel and also had an old school-type chair lying around so decided to cut that up and use the steel legs from that.
Step 2: Step 2: Grinding/Cutting
Ok, so actually starting making here!
To enable the sheet steel to bend evenly you need to grind a groove on the inside, kind of like scoring card to fold it.
I cut the strip 1200mm long x 250mm high from the sheet that would be the main body and marked it out.
The box finishes up at 500mm long x 200mm wide x 250mm high
To bend it at the corners I used the angle grinder but I suppose you could use a large hack saw if you needed but its worth getting yourself a grinder for this build as it save alot of time.
firstly I used a fine 2mm cutting disk (sold for cutting stainless steel but great for a fine slot) to cut a groove then used a normal cutting disk (approx 4mm thick) to widen the slot. I cut about 3/4 of the thickness of the steel to weaken it enough to get a good fold.
For the door opening I marked the curved top and used the thin grinder again and a jigsaw to cut right into the corners and finish it off.
Step 3: Step 3: Folding and Welding
Main Box Body: When it came to bending the box I realised it was tougher than I originally thought. I didn't want to cut away too much steel in case it split. It actually did split in one corner but I wasn't too worried as I was planning on welding it all from the inside anyway.
I ended up using a blow torch to heat the area to be bent first to soften the metal then used brute-force and a bit of elbow grease to form the box.
So once the box is formed you just run a bead of weld down the inside of the corners - this doesn't need to be too neat as it is never seen so use this as practice for the more visible bits. I also welded the front together inside and out and ground that flat. most of this joint will be visible so it needed to look nice.
Baffle: Next, I cut the piece I would use as the baffle which went nearly the full length of the box from the back, leaving a small gap at the front of about 30mm for the hot air to be forced around for the secondary burn.
Top: I then cut out the top and welded that in place, from the outside - so these welds had to be solid as well as look nice. so take your time! I rounded the corners so I didn't keep catching myself on them and made the top bigger by about 50mm all round so the top surface was more usable. So the top piece is: 600mm long x 300mm wide.
I cut the hole in the top of the stove by drilling out in a few places around the circle then cutting it out with the jigsaw. This piece I then kept to use as the damper in the flue.
Bottom: I then welded some little tabs inside underneath for the base to fix to and drilled and taped them to accept some nice little countersunk allen-keyed bolts I had. The base sits flush inside the bottom. I didn't take any photos of this at the time but will try and take a few snaps of it finished.
Step 4: Step 4: Door, Hinges and Air Vents
Door: I cut the door from some more 4mm sheet. its 10mm bigger all round to allow for a good seal with the rope. The fire rope was bought from Ebay and it came with the correct glue and its great, it gives a really good seal on the door.
I originally planned to fit a window in the door but decided it was too complicated for this box so I went for a large vent on the front. This hasn't been a problem really as if you want to see the flames you can just leave the door open and it still burns pretty well like that.
Hinges: for the hinges I cut some small tabs of flat bar and drilled them out to accept a piece of 6mm round bar. I used a piece of 6mm threded rod through both the hinges to line them up to weld then removed it and welded the round bar into the bottom ones.So the door can lift of the hinges leaving the pins in place on the box. (See second photo)
Vents: For the Bio-Hazard vent I marked the shape out, drilled out the corners of the shape and then just the jigsaw to cut it out. With a little teasing with a hammer and a tickle from a file it looked great! Sadly I was too busy smashing it to take photos as I went along.
I have since fitted a thin vent cover over it which rotates to reveal the holes and has a wire handle so it doesn't get too hot.
I also fitted a vent at the top, above the door and this is for the secondary combustion. this was very simple to make and I just placed the flat bar on the front and drilled through both pieces to line the holes up. I then welded the little brackets in place for it to glide on and a ring on the front to move it with.
Step 5: Step 5: Flue and Legs
Flue Pipe: I bought a 3m length of 4" mild steel pipe with a wall thickness of about 2mm. It didn't need to be massively thick as a lot of the heat is absorbed into the body of the stove. I got this from a local metal supplier for about £50
for this stove I cut a length of 500mm and 1000mm and made a simple tab mechanism to join them with a pin.
I figured I would only need it to be about 1.5m above the top of the stove (about 2m from the floor), so long as its above head height that's enough.
Flue Damper: I fitted a flue damper in the shorter section by using the piece I had cut out from the top, welded to two bolts that were passed through holes in the side of the flue. This was a bit fiddly as I had to weld the bolts on, inside the flue. I then welded on a little lever to operate the damper from the outside.
I used an old 24" steel ruler that was rather bent and useless to make a collar for the flue to fit too. I was going to do the same pin join with that but its such a tight fit that I didn't bother. I rolled it to make a nice circle then welded it in place around the hole in the top.
Legs: I used the legs of an old school chair (example attached) and welded some nuts to the inside of the stove and then sent a bolt through the side so I can remove them for transportation.
Step 6: Step 6: Spray and Finish
Paint: When I had finished the stove I sprayed it with Plastikote WoodStove Paint from ebay (LINK) which is heat resistant and lasts a good few years - the stove has been outside for the best part of 6 months over the winter and its still fine.
Before spraying make sure you file all the rough edges and lumpy welds and sand the surfaces with some Emery Paper to give a good 'key' for the spray.
The spray I used needed 'cooking' afterwards to cure it so I lit a gentle fire for several hours when I got it home. After that you can have it as hot as you like - I've had the sides glowing straw yellow and the paint still hasn't come off!
Grate: I made a simple grate out of some thick wire mesh but eventually plan on making a better designed one as it tends to bend in the middle and I have to flatten it every time I use the stove.
The finished product is great and have already have offers for it and at least 2 serious request for me to make people their own ones.
The top is large enough to get 2 medium sized pans on the go -cooking at different speeds as its hotter nearer the front. When up to temperature it boils a basic camping kettle in about 5mins - if you had a proper cast iron kettle it would be even better!
Hope you enjoyed my first Instructable and let me know of any questions and I'll try and respond!