Funky Portable(ish) Pizza Oven

There is nothing finer than a perfectly cooked wood fired pizza, I love the stuff!

This pizza oven was a bit of a trial based around two previous ovens and turned out amazing, it cooks superb pizzas. It all started when I was fed up with tripping over some helium party cylinders that were used for some of my daughters birthday parties. Once I found out they were 12” I decided to turn them into a pizza oven.

I had a problem with my two previous ovens, either the top or bottom of the pizza would cook before the other, this was due to the way the respective ovens were built. This pizza oven is designed to cook the pizza from above and below at the same rate. This is achieved by a heat shield below the pizza stone and also an adjustable inlet for fire in the base of the oven. I also wanted the pizza oven to be small enough so I could take it camping with me, assuming I had the car to take it in.

Some tools are needed for this project but if you’re a pizza loving tinkerer, like me, then this will be perfect for you.

Tools

Angle grinder

Drill (with drill bits and screwdriver bits)

1mm metal slitting disc

120 Grit Sanding disc

Pipe bender for 22mm pipe

25mm metal hole cutter

Ceramic/masonry slitting disc

Materials

Domed cylinder preferably 12” in dia

Bolts (M2 x 6mm and M4 x 10mm)

Stainless steel sheet metal (600mm x 1000mm x 1200mm)

Pizza stone to fit cylinder (12” diameter)

Wire rack (12” diameter)

Angle iron (20mm x 20mm, 3mm thick, 300mm long)

Copper pipe 22mm diameter

6 x 90° copper elbow (plumbers couplings)

Hinges

Handle/latch

High temperature paint (good for >600°C but the higher the better)

The key point when working with any cylinders is safety and the details below are for the specific cylinder I used. I would investigate the cylinder you are using to ensure that you are working safely with it.

1. Ensure that the cylinder is empty of any gas.
2. Drill a small hole in the safety release valve (blow out valve).
3. Using the angle grinder to remove the handles and valve (you might want to do this later in the build if the handles help with stability throughout the build). If the handles will make good feet these can be left on.
4. Mark out the position of two doors, one will be used to get the pizza in and out and the other will be used to tend to the fire.
   1. The door for the pizza wants to be 1/3 of the way down the cylinder and approximately 50mm wide. This needs to run all the way around the side of the cylinder to its widest point. This will be half of the circumference (I’ve made that sound way more complicated than it needs to be… the door needs to extend halfway around the cylinder), in my oven it extends for 500mm.
   2. The door for the fire wants to sit directly below the door for the pizza and extend down to just before the curve at the bottom of the cylinder (the dimensions of mine were 210mm x 150mm)
5. Carefully cut the two doors our using the angle grinder and use the sanding disc to remove any swarf or sharp edges.

The inlet at the bottom of the oven will allow us to control the temperature of the oven (and mainly the heat above the pizza, sounds counterintuitive but a heat shield will control the temperature of the pizza stone) by adjusting the amount of oxygen getting to the fire. It consists of holes in both the cylinder and in a sheet of stainless steel running around the inner diameter.

1. The first job is to make the holes in the cylinder. Measure the distance around the back of the pizza oven between the edge of the doors i.e. the distance in which the holes will fit.
2. 20mm above the curve of the dome in the base of the cylinder, draw a horizontal line all the way around the circumference.
3. Draw a second line around the circumference 50mm above this.
4. Now divide the distance measured in 1. by 50mm (width of the holes) then divide this by 2 this will allow for a 50mm gap in between the holes. On my oven I have 7 50mm x 50mm holes
5. Use the angle grinder to carefully cut out the squares marked.
6. Use the sanding disc to remove any sharp edges.

The second job for the fire inlet is to make the inner sheet that runs around the cylinder.

1. Use the length measured in step 1. of preparing the inlet for the fire - cylinder.
2. Mark the length from 1. x 75mm wide onto a sheet on stainless steel (make sure the inner sheet is 25mm wider than the holes in the cylinder).
3. Mark a handle (65mm x 60mm) an 1/8th of the way down the rectangle, round rectangle edges, this to be used to open and close the holes on the inlet.
4. Cut this out using the angle grinder.
5. Use the sanding disc to remove any sharp edges.
6. Bend the sheet over a rounded object until to matched the radius of the cylinder.
7. Bend the handle at approximately 50-60° outward /away from the inner diameter.
8. Fit this up against the inside of the cylinder and mark where the handle will stick out. For my oven this is 15mm down from the holes and 130mm long. This may need to be adjusted once the holes have been cut into the inner sheet.
9. Use the angle grinder to cut the a slit for the handle.
10. Place the sheet on the inside of the diameter with the handle fitting through the hole.
11. Make sure the handle is pushed all the way to one side of the slit (make sure you have enough room on the opposite side of the slit so you can extend it so you can close off the holes fully) and mark the holes by drawing around the holes in the cylinder onto the sheet underneath. Also mark any excess material that hangs over the door. Push the handle to the other side of the slit and make sure the slit for the handle is long enough so that the holes you have marked can’t be seen, if it is not extend the slit. Also mark any excess that now hangs over the other side of the door.
12. Use the angle grinder to cut out the hole and cut off any excess material from the ends.
13. Use the sanding disk to remove any sharp edges and round the ends.
14. Cut 5 off 10mm lengths of the angle iron, this is to support the inner sheet.
15. Drill a hole in one face of the angle iron.
16. Fit the inner sheet to the cylinder/pizza oven.
17. Position the angle iron in the correct place to support the bottom of the inner sheet and mark the position of the holes.
18. Drill the holes and use a bolt to fasten the angle iron so the ‘non-drilled’ face is upward to support the inner sheet.

The heat shield is designed to work similar to the air inlet by having a disk on top of each other and these will have two sets of over lapping holes sitting just below the pizza stone. This will allow us to adjust how much heat gets from the fire up to the pizza stone. The heat shield will be at an angle and will have gap at the side to ensure the majority of the heat can get into the dome.

First we need to produce a carboard template of the heat shield, this way we can ensure we have an accurate dimension before we then trace it onto the stainless steel sheets.

1. On a piece of cardboard draw a circle the same diameter at the pizza oven/cylinder, extend the edge of these by around 2.5mm making an oval to account for the angle of the heat shield.
2. Fit this up against the pizza oven to see how accurate it fits and make any adjustments necessary. Make sure there is an angle, the exact angle is not critical but I used an angle of approximate 20°
3. Make sure it is approximately 5mm (at its closest) below where the pizza stone will sit (20mm below the bottom of the door), the pizza stone will fit just above the bottom of the door designed to get your pizzas in and out.
4. Cut one end of the oval off by 50mm to allow heat up to the dome of the pizza oven.
5. Mark this out twice on the stainless steel sheet.
6. Add tags onto the bottom plate of the heat shield, this is so it can be fastened directly to the pizza oven/cylinder. These want to be approximately 25mm x 25mm
7. Add a handle to the top sheet so that you can open and close the holes on the heat shield, this wants to be 65mm x 60mm.
8. Use the angle grinder to cut out these circles remembering NOT to cut off the tags or handles.
9. Use the sanding disk to remove any sharp edges.
10. Mark equilateral triangles on one of the sheets approximately 90mm x 130mm (this wants to be cut short by 20mm-30mm to make a trapezium), leaving a gap of the same size in between.
11. Use the angle grinder to cut out the triangles.
12. Use the sanding disk to remove any sharp edges.
13. Place the second circle over the first and mark the triangles through the holes.
14. Use the angle grinder to cut out the triangles.
15. Use the sanding disk to remove any sharp edges.
16. Drill a hole right in the centre and fasten a bolt though this, apply two nuts to the bolt so they can be tightened against each other while ensuring the plates can still spin on top of each other. The best way to do this is to tighten the first bolt finger tight and loosen ever so slightly, then tighten the second bolt up to the first.
17. Drill a hole in the centre of each tag and then bend each one down at a right angle.
18. Mark and cut a slit for the handle of the heat shield in the cylinder.
19. Place the heat shield on the inside of the diameter with the handle fitting through the hole. Making sure it is at the correct angle.
20. Mark the position of the holes from the tags onto the inside of the cylinder.
21. Drill these through from the inside of the cylinder, you can make this easier by doing a pilot hole then a larger hole (to suit your bolts) from the outsize of the pizza oven/cylinder.
22. Fasten the heat shield in place with the bolts.
23. Make sure your handle will fully open and close the holes of the heat shield and make any adjustments as necessary.

The support for the pizza stone consists of angle iron mounts to hold a wire mesh that the pizza stone rests upon.

1. 15mm below the door draw a line around the circumference of your pizza oven/cylinder.
2. Mark the position of the bolts for the 5 angle iron supports and drill these.
3. Cut 5 off 10mm lengths of the angle iron, this is to wire mesh for the pizza stone.
4. Drill a hole on one face of the angle iron.
5. Fasten the angle iron so the ‘non-drilled’ face is turned upwards to support the inner wire mesh for the pizza stone.

The aim of the pizza oven is to cook the pizza from underneath and above equally, the position of the chimney is designed so that the heat remains in the dome of the oven for longer to increase the temperature. We will need 6 chimneys for this size oven.

1. Draw a straight line around half of the circumference opposite side from the pizza door 40mm higher than the where the pizza stone will sit.
2. Find the centre of this line and mark a hole 25mm either side of the centre line. Mark 2 more (4 extra) holes either side of this with an 50mm distance between the centres of the holes.
3. Just check that the hole cutter is the correct size for the 90° plumbing elbows by doing a test drill on either some spare wood or metal and checking the threads will fit snuggly, with only the tiniest bit of play
4. Using the hole cutter to cut the extra 4 holes marked.
5. Get your 90° elbows and slit one of each nut in half through the circumference. This is so that we can trap the wall of the pizza oven/cylinder between the two halves.
6. Fasten each of the elbows to the pizza oven working from left to right in order to tighten them one by one.
7. Take the length of copper pipe and cut this into 6 off 530mm lengths, using the angle grinder with slitting disc.
8. Use a pipe bender to bend the pipe to follow the contour of the pizza oven roof, once the first one is done this can be used as a guide for the others.
9. Fasten these to the 90° angle, position to be even and tighten the nuts on the angle.

You need to buy a decent pizza stone in order to cook the pizzas on, I bought one made from Cordierite and it has been great with no issues.

1. Measure the internal diameter of the pizza oven.
2. Buy a pizza stone… of the correct size.
3. Wait for it to arrive…
4. Mark a straight line 50mm in from one edge (to match the gap at the side of the heat shield).
5. Cut the edge of the pizza stone off using a ceramic/masonry slitting disc.
6. Smooth the corners off the cut edge off.

We need some fixtures in order to ensure our doors will open and close, and stay closed.

Hinges

1. Position the hinges in place one by one on each door and mark holes for drilling, I recommend 2 for the fire door and 1-2 for the pizza oven door (obviously this depends on how big the hinges are).
2. Drill the holes for each hinge and repeat on steps 1 and 2 for the cylinder/pizza oven wall.
3. Use bolts to fasten the doors on to the pizza oven.

Latch

1. Using the same process as the hinges position a latch on each door.
2. Position the latch in place one by one on each door and mark holes for drilling.
3. Drill the holes for each latch and repeat on steps 1 and 2 for the cylinder/pizza oven wall.
4. Use bolts to fasten the latch on to the pizza oven.

The thermometers are used to monitor the temperature above and below the pizza. Position one in the roof and one between the top of the heat shield and base of the pizza stone. I used BBQ/Smoker/Grill thermometers.

Roof

1. Mark a line vertically between the chimney and the centre of the door.
2. Mark half way along this line.
3. Drill a hole suitable to fit the probe of the thermometer through and fasten in place.

Door

1. Find a suitable position between the top of the heat shield and base of the pizza stone.
2. Position the thermometer on the outside of the oven to ensure it doesn't interfere with any parts of the oven, mainly the handle to adjust the heat shield.
3. Mark this position.
4. Drill a hole suitable to fit the probe of the thermometer through and fasten in place.

If you cannot use the handles of the cylinder as legs, you will need to make some. First we need to make a cardboard template:

1. On a bit of card mark out the size of the leg (mine were 210mm x 65mm face and 170mm x 45mm sides)
2. On the sides of the legs mark the curve of the base of the cylinder.
3. Use the template to mark 4 legs onto the stainless steel sheet.
4. Use the angle grinder to cut out the legs.
5. Use the sanding disk to remove any sharp edges.
6. Drill two holes at the top of the legs to fasten to the pizza oven.
7. Bend the legs to form the side and the front.
8. Fasten to the pizza oven using bolts.

Now the fun part, adding some colour to everything. Sorry to say it… but it is worth taking everything apart at this point to get the best finish possible on the surface. I recommend not using too light a colour, as there will be some soot residue from the fire that will leak out of the doors. I went for a nice forest green colour.

1. Use the sanding disc to remove all of the old paint.
2. Spray paint in light, even coats as per the instructions for the specific paint.

Leave to dry and fasten everything back together.

I love pizza and have spent a while trying to master the perfect pizza, this pizza oven has been great for that. When I’m using the oven I use a base heat from charcoal and 3-5 bits of kindling to increase the temperature while cooking each pizza.

After using my pizza oven for a while, I always have the settings of my heat shield and fire air inlet the same. The heat shield is always closed and the air inlet is always open. I have not tried it, but I expect you could build the oven with no inner sheet on the inside of the cylinder for the fire air inlet and you could just have the holes in the cylinder, and you could have a solid heat shield to sit below the pizza stone. The heat shield will still need a gap at the side to ensure the majority of the heat can get into the dome.

If you try this simplified build, let me know how it goes, I would love to know the outcome.