Brake Drum Potbelly Heater

Intro: Brake Drum Potbelly Heater

I was sick of working in a cold workshop and wanted a heater that will last forever without costing the world. Reusing old truck brake drums is a fun, easy and cost effective way to make a potbelly heater that will stand the test of time and perform great giving you heat in the coldest of conditions for years to come. I don’t like wasting anything so by reusing old scrap metal to make a heater proved a great way to repurpose it into something useful.

So this is how to make a potbelly heater from old truck brake drums. No welding to cast necessary.

Note: You can weld to the cast iron drums if you wish but I’ve found keeping it in seperate pieces makes it easier to move if/when needed, as the drums weigh 40kg each.

Tools Needed:

. Grinder/Cutting & Grinding Discs

. Welder

. Press or Roller

. Oxy Torch (Not necessary but makes life easier)

Materials Needed:

. 130x10mm Flat Bar

. Heavy Walled Pipe

. 3x Truck Brake Drums

. 3x Chipping Hammers

. 12mm Round Bar

. 5-10mm Plate

. 7x 3/4” Nut and Bolts

. Exhaust Paint

Safety:

Be sure to wear all Personal Protective Equipment necessary to complete the job safely. Also keep in mind while grinding the cast iron if it gets too hot the grinder tends to grab so be sure to use extra caution.

STEP 1: Finding Brake Drums

Get 3 truck brake drums from your local truck depot or metal recyclers. If you can get them for free awesome, otherwise they should cost between $15-$20 AUD each.

STEP 2: Cut Out Ash Door

Cut a hole out of the base drum this is so you will be able to remove the ash and charcoal from your heater. Keep in mind this will also act as the air intake for your heater so don’t make it too small. The opening pictured here is 120mm x 250mm.

Note: Cast iron cuts very poorly with an oxy so it’s best to use a grinder or plasma cutter. While cutting with a grinder may take longer initially it will save you a lot of work in the long run.

STEP 3: Weld Grate and Bolt Drums

Bolt the two bottom drums together (four 3/4” or so bolts will be plenty) and weld up a grate. I used some scrap square bar I had lying around.

STEP 4: Bend Up Bar for Mid Section Ring

Bend some flat bar for the mid section of the heater. I cut it into three pieces because it was easier to bend short pieces with the shop press (if you have a heavy duty roller it would be perfect as you could roll it in one piece). Follow the curve of the lip on the brake drum. Then weld the 3 pieces back together to make a ring. The flat bar size used here was 130x10mm. The ring should sit nicely over the lip of the bottom brake drum and the top brake drum lip should sit inside it. See pictures for clarification.

Note: You can use any size flat bar depending on the height you want between the drums. I recommend however, going at least 10mm thick as this needs to support a lot of weight while under heat.

STEP 5: Ash Drawer

Weld together a drawer to catch the ash. I used some 5mm scrap checker plate and a chipping hammer handle for the handle. Make the drawer as long as possible as this will also act as your air intake for the heater. When pulled out slightly you’ll still want the length in order to catch the falling coals.

STEP 6: Cut Out Openings

Now cut out the opening for door and flue. Grinder worked fine just takes a bit of finessing and patience to get it how you want. Also drill a 20mm hole for the door to bolt to.

Note: Keep in mind cast iron cuts very poorly with an oxy torch. Use a grinder or plasma cutter if you have one.

STEP 7: Cut Top Plate & Mark Out Flue

Cut top plate using an oxy works best. Cut in half depending on the size you want for your door/flue. I used 10mm scrap plate. Mark out your flue, this will help you see how it will look. I’ve used 6 1/4” heavy walled pipe for the base of the flue but anything 5” and up will be fine.

STEP 8: Attach Door

Cut the top off a 3/4” bolt and weld it underneath plate to be bolted to drum. Alternatively you could just use a nut and bolt. Round off the edge near where the bolt is to allow the lid to swivel open.

STEP 9: Attach Flue and Door Handle

Weld the flue to the top plate be sure to weld the top and bottom for strength. I used some scrap 6-1/4” heavy walled pipe for the base of the flue. Make sure the hole cut for the flue isn’t restricted in anyway as this will effect performance. Again use a chipping hammer handle for the door.

STEP 10: Flue Damper

Weld in a flue damper. I used scrap 5mm checker plate. Run a 12mm round bar with a flanged end through to weld disc to. Also added a spring on the other side to help keep tension when the flue is under draft. Welded chipping hammer handle on also.

Note: The flue damper is the most important part for the heaters operation, this damper controls the temperature as well as aiding shutdown. However, do not stress about tolerances. You’re better to have a bit of play to allow for the heat, soot and rust over the years that may begin to clog it up if you make everything fit too tight.

STEP 11: Final Assembly

Assemble everything together make sure your happy with it. Check all parts that they function correctly. If any changes are to be made now is the time.

STEP 12: Optional: Prep and Paint

Run over and remove all/any rust with a wire wheel. Wipe down with metho. I used VHT Flameproof Black says it’s good for 704-1093°C. Apply paint and allow to dry for 7 days.

1. Heat to 121°C (250°F) for 30 minutes. Cool for 30 minutes

2. Heat to 204°C (400°F) for 30 minutes. Cool for 30 minutes

3. Heat to 343°C (650°F ) for 30 minutes.

As far as possible try to follow instructions closely for best outcome.

Caution: The first time running the heater there will be fumes while the paint cures. Please be aware of this and run the heater in a well ventilated area.

STEP 13: The Performance

Here are some temperature stats that might be of interest. If there’s anything else you’d like to know that you would like covered please comment below.

At normal running the temperatures are as follows:

Flue: 210°C - 320°C (410°F - 608°F)

Top Side of Heater: 365°C - 450°C (689°F - 842°F)

Bottom Side of Heater: 550°C+ (1022°F+)

Size of Shed: 6.5m x 7.5m (21.3’ x 24.6’)

Outside Temperature: 3°C (37°F)

Inside Temperature of Shed: 42°C (108°F)

STEP 14: 2 Years On

So it’s been 2 years since I made the Instructable and the heater is still going strong as ever. The paint is coming off in places as was expected being a heater I wasn’t confident it would last forever. There’s not much I’d change except making the steel grate at the bottom from something more solid than square tube as I burnt through it (granted it did take 2 years). I’ve had it glowing red a couple of times which is crazy especially considering the drum is at least 18mm thick in most places. If you have made it or have anything that you have done that’s different let me know I love to see what people make it give me further inspiration.

Comments

[Mack253]

Hi Lachie, just got a few questions mate is there a way I can contact you before I try take this project on

[lachies_restorations]

Just sent you a message

[HalconGT]

Que bonito e interesante ya que trae todos los datos. Iré a buscar los tambores y poco a poco espero hacerlo. Gracias

[TreeTreeTreeee]

For the air intake(s) drill and pipe-thread holes. Thread in short lengths of black iron pipe and control air flow with pipe caps.
I envision cutting short slots in the pipe lengths so complete removal of the caps would not be necessary. Multiple openings would likely be needed.
No concerns about alignment of the ash drawer.

[James8]

Can you tell me if anyone has reached a temperature that would vitrify ceramics melting glazes.

[lachies_restorations]

Not with this heater, hottest I’ve got it naturally is around 660 C°

[Daeras]

Have you considered to install a sleeve unside the firebox to try and get a secondary combustion cycle going.

If you find a steel pipe that will fit inside with a small gap between the drums and the pipe and you weld it closed at the top and bottom. You would probably need a double skin baffle with small holes at the tip on the inside and some holes on the outside at the bottom you might just accomplish secondary combustion.

The air in the gap would heat up and if it gets hot enough, it will combust the smoke as well and would become much more wood efficient.

[lachies_restorations]

No haven’t thought of that but it sounds interesting, secondary combustion would be awesome. I’ll look into it. Thanks

[Norm1958]

What would happen if you slipped a pipe around the stove, holes to the outside at the bottom and holes into the brake drum at the top?

[Ricardo Furioso]

Thank you for sharing your work.
This is spectacular. And inspiring. And additionally great considering you had to constantly work against that peculiar Sideways Gravity you must be suffering from there in Australia.

[lachies_restorations]

Haha thanks glad to help. Don’t know what happened to the pictures they used to be the right way up...

[Stewie81]

Hi Mate,
Fantastic instructions, at this stage all seems easy to follow. Only question I do have is if you could please provide more info/detail/pictures about the spring setup in the damper

Thanks in advance

[lachies_restorations]

G’day I’ve added a close up of what I did with a couple of instructions. I used a spring from an old lawnmower valve and washer from my cars old shocks. Lightly compress the spring against the flue wall then weld the washer on (I tack welded the spring to the flue but it’s not necessary). It doesn’t need to be crazy tension. I then welded the handle off the end of the rod. Hope this helps let me know if you need anything clarified.

[Stewie81]

Thanks fella. I think it makes sense. Where about are you roughly located? Just in case I need to come see for myself. Only of course if you are willing

[Stewie81]

Thanks fella. I think it makes sense. Where about are you roughly located? Just in case I need to come see for myself. Only of course if you are willing

[CaraD15]

I was wondering what size the drums are?

[lachies_restorations]

They are for 16.5” brakes. The outside dimensions are roughly 460mm for the wide opening, 340mm for the narrow side and 280mm high. Hope this helps.

[Ssnatsy]

Ive build kinda the same heater but its also different but he burns like hell

[lachies_restorations]

Thanks for the pics. They go hard! How do you find the middle door? I’ve considered doing that but opted for the top.

[Ssnatsy]

Only the hinges keep bending because of the heat i geus.
I couldent make the door on the top because there wassent enough room haha.
And i also have let the holes in the rims so now the top acts like some kind of
afterburner