Woodburning Stove From Sheet Steel

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Posted in WorkshopMetalworking

Introduction: Woodburning Stove From Sheet Steel

About: My mantra has always been: "I'll have a go at that!" and why not? Humans have lost too many practical skills so lets get sharing and revive our former hands-on selves!

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!

Cheers

GarlicCharge

2 People Made This Project!

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48 Comments

Absolutely perfect. I've been looking for my next welding project and this is definitely it! I was going to buy a stove, but this is exactly what I was about to drop £250 for the stove and £250 for the pipe for. I was considering using one of my decommissioned "gas" bottle stoves but I'd not finished it off like this had - it's much neater. Also I might do it in Stainless.

7 replies

Ohhh stainless. didn't think of that. might get a bit pricey though. you could always cheat and use a chrome spray?... I was going to do a gas bottle stove to begin with but started this instead. Thats next I think. Thanks for the comment!

I'll save you a lot of money with this reminder: Heat transfer is not good at all with stainless steel! It would take a long time for the thing to start heating your room and in the mean time your flue and chimney would be getting really hot.

Very pricey. 2m x 1m mild is £83? and Stainless is £400. Fortunately a friend is a stainless steel kitchen fabricator. I'll ask for offcuts. Or I may just out and out ask him to make me one. He likes having a play. Will be a bit ugly with a mild steel pipe coming out the top, but fun nether the less!

Do share if you make one! The steel I used was an off cut so didn't cost me anything either! free stuff is best! :D

Free stuff is indeed the best. I have now sourced a free 2x1m 5mm sheet. We've cut two stoves from it by rejigging your design a bit for the sheet and fortunately my friend has access to a bender and a plasma cutter, so he's bent the sheet for me and is cutting the door out of the flat front bit (no one looks at the back of the stove anyway :)

He had photos, but they're on a potato phone so I'll take a picture of the main body when he drops them round.

I'll weld the rest myself with my stick welder.

The flue (again, free!) is 1.5mm thick 4" pipe which is good. We're doing 500mm section and 1000mm section. I think he's going to weld the joining pieces for me.

So hopefully some pics soon. He's welding the other stove himself on the tig.

this is amazing! well impressed someone has actually made one. hope it goes well for you. do share your pics. good luck and happy stoving!

Just to let you know the first stove is nearing completion. He's built off your design and added to it. We've got a nice stove grate that sits just off the floor allowing the ash to fall down using some angled steel and it comes out of the door hole. Really quite excited to see the finished product now...!

GarlicCharge - check these pics out :)

Also look at the ash grill... so pretty...!

photo 1.JPGphoto 2.JPGphoto 3.JPGphoto 4.JPGphoto 5.JPG
2 replies

woah! this is awesome! I can't actually believe someone is making a stove from my plans!

btw, your cutting is much neater than mine!

watch those corners on the top, they look sharp! - I radiused mine to about a 50mm curve.

I want to build another one now! :P

The advantage of having someone who's an industrial metal worker with all the tools, presses and a CNC machine at my disposal! My cuts and welds would be much worse than yours! Just check them out on my latest instructable (involving bacon)

https://www.instructables.com/id/The-windscreen-wip...

That's my welding and cutting. Very wonky!

Using an uncertified stove will nullify your insurance policy

1 reply

You're absolutely right! Yes, all stoves for use in a UK home need a HETAS registration document and in many areas need to be DEFRA approved. This stove is intended for outdoor use i.e. when camping. When I mentioned a small room, I was thinking more of a workshop scenario where insurance might not be a problem.

Love it! I think every home needs a woodburning stove! Awesome!

Thanks guys, really appreciate it. Hope it inspires others to get building!

this is very nice, great metal working.

Great design! I'm now busy planning a stove based on your design.

Hi there, great instructable! I'm looking to build a bigger version of this fire - 50-75% bigger and am basically wondering if you think I'll run into any problems by simply scaling it up? I guess I'm thinking about efficiency, and draw from the chimney especially. I'd hate to build it bigger and then find I'm not getting enough air circulation or draw from the chimney. Any thoughts appreciated.

Thanks again for putting this up!

1 reply

The sizes I did were down to the size of material I had. I had a little left over but not a lot. The biggest consideration is the folded sides as they determine the width/length of the initial sheet. I hope this makes sense. you could always make each side individually and weld them, therefore you could use any size of material and you may be slightly more economical. GC