Barrel Oven Build Part 1 - External Metal Parts

So quite some time ago we decided to build a barrel oven, all the better to feed ourselves with whilst building which had become more of a challenge as more people got involved. I found it quite difficult to find anything approaching a detailed account of how to build a barrel oven. Lots of stories, very light on the specifics. I have the barrel ovens book from Firespeaking, which is quite thorough on how to do the brickwork, and found a few blog posts about the interwebs that helped. Most useful is probably this one, but it doesn't mention measurements or anything. There wasn't anywhere that could tell us in detail how to do the metalwork (mostly people just say "give some pictures to your local backyard welder dude" but since that's us we had to work it out), so we just sort of went for it, trying to think it through logically and come up with something that looked like it would work pretty good. We figured we might as well document what we did so that someone else can follow this for some tips and not have to work it out from scratch like we did.

I sketched up the parts based mostly on these two images:

 

Then I worked out the measurements based on a 55 gallon drum we bought at the tip, as everything had to fit around that. The front of the barrel will be flush with the front of the whole oven, and the front of the ash grate will be too, we want the outside of the ash grate to be about the same length as the barrel.

For the width, I figure it's best to judge this from the size of the bricks we're likely to be able to use to build the oven and make that + a mortar gap equivalent to the inside edge of the ash grate so that it can rest on the brickwork. This presents us with a problem as we haven't got them yet but would still like to begin the metalwork. Apparently the length of a standard brick is 22.5mm (again, trusty Wikipedia), and since the consequences of getting this bit wrong are that we'll spend a bit of extra time cutting bricks to size or getting creative with how we lay them it seems fair enough to run with that number.

I put these measurements together with my sketches and produced a cut list for Kyle and Baz (our handy blacksmith friend who's also good with a welder).

We ended up buying new metal as it was a lot quicker than accumulating tip shop offcuts and we had a long weekend we wanted to get it all done in. Cost us about $250 all up, and we had all the welding gear already between the three of us. The metal shop could have done most of the cutting for us, but they were a bit busy so it would have taken them three days and we wanted to get it done over the weekend. And so commenced the Long Weekend Weldathon of 2018.

Starting with the Ash Drawer we added a couple of little bits of angle iron in the corners to stabilise the structure as we were only using 2mm plate. All the welds went on the inside so it would sit flush against the brickwork. The welder was new (well, new to us) so there was a fair bit of trial and error and complaints about dodgy welds before they were happy with it.

  

We left a 10mm lip around the edge of the front of the drawer, and Baz is going to use his Mad Blacksmithy Skillz to make a handle out of offcuts a bit later on. I don't think the boys welded all the way along, just tacked down an inch or so every so at regular intervals along the edges. The drawer took maybe 3 hours all up, including all the setup, cutting and finishing.

Next came the Ash Grate, dimensions of which are based entirely on the drawer (the idea is that ash will drop through the grate into the drawer, but the burning wood stays on top). We had many extensive discussions about how far apart the bars should be and eventually settled on 10mm rod with 20mm between, after consulting many internet images and painstakingly counting how many bars they had. The grate took about 2 hours, and most of that was cutting and getting it all square.

   

Next came the Firebox Door, slightly more complicated but still pretty straight forward. We did an angle iron frame for the door frame, then a smaller angle iron frame around the edge of the door itself, and a strip of flat bar for the latch mechanism. The boys did something fancy (well, they thought it was fancy) with the hinges to get it all to open and close smoothly, but I was out getting insulation at the time they worked that out so I'm not entirely sure how it all worked.

   

Again, handle and latch from random offcuts a bit later on. One thing I noticed in some of the pictures I found was that there's a small piece of metal rod at a diagonal connecting the firebox door and the ash grate, to hold the door frame in place. This seemed like a pretty good idea to us, but for ease of storage in the mean time we'll only add that when we go to actually build the thing. That way we can also adjust bits as needed while we set the bricks around each part.

We tackled the Shelves next. I figured the mesurements after messing around with a tapemeasure up against the end of the barrel for a while and seeing what looked about right. After finding it almost impossible to find steel mesh that wasn't either painted or galvanised we went with the lesser of two evils and then vinegar-washed the galv off. We couldn't find a wash tray big enough so I made one with duct tape and corflute and lined it with a sheet of clear plastic so it wouldn't leak. I think we added a bit of hydrochloric acid at one point too because we got tired of waiting for the vinegar to work and didn't have time to leave it all night.

We strengthened the mesh with 10mm steel rod all around the edges, and another across the middle, so the shelves would stay flat rather than sagging over time.

The Racking for the shelves was the only part where measurements became a bit more important, in the sense that every other part once we cut things to length it just had to all go together, whereas with the racking we had to weld it at a particular spot. This is so that when the oven is eventually built the shelves sit perfectly level and our cakes don't end up wonky or spilling out. This was pretty fiddly, and was achieved mostly through meticulous use of calipers and squares. The distance between each of the uprights was determined by the rippling on the edge of the barrel, so anyone using a slightly different barrel to ours will have very different m

   

Finally, cleaning the barrel out was the topic of many discussions and an awful lot of messiness. We did search high and low for a place that would sell us a fresh new one, but the conclusion was that unless we wanted 1000 of them no one would even talk to us, so we had to clean out a used one we found at the tip. Eventually we cut off the end (with a chisel, a bit like a can opener) and Kyle scrubbed it several times with methylated spirts, then several more times with warm water that had super concentrated detergent in it. Kyle had to kind of climb inside it with each rinse (strongly recommend very good breathing equipment for this part, even the detergent stage). It seemed to work pretty well, but we'll be very careful the first time we fire the whole thing up anyway.

We bolted the racking to the inside of the barrel, which was the other part of the whole operation that really had to be totally meticulously perfect (to achieve level shelves) then done! Levelling the racking was a multiple-person job involving several spirit levels and a lot of swearing. I don't have good tips for this because I'm pretty convinced the way we did it wasn't very effective, though if you're in the mood it did occur to us later on that if we'd sat the barrel up vertically we could have done it off a plumb level rather than tried to hold the whole thing flat.

The last part of welding was the Oven Door, which we did last because we weren't quite sure how it was all going to work. This bit took quite a while to work out, so deserves a post all of its own, in Part 2.

A sink table

So we've been planning the outdoor kitchen for a while, and as part of that we want a barrel oven (eventually) and a place for convenient washing up. Thus, the idea of a sink table was born - a semi-mobile piece of outdoor furniture to make washing up a breeze. At least, more of a breeze than it is now with 5 people stuffed into my parents tiny motor home with one mini-sink.

We bought a sink from the tip ($10) - we wanted one with two sinks and two drainage boards, to make large batches of washing up easy.

With some bits of timber we had already (also from the tip, around $15) Kyle made a frame for the sink to sit in.

You can see the very technical numbering system that kept it all in the right place:

Once we had the frame, and the sink was screwed on (with screws from the tip - $0.50) Kyle started on legs. First he checked that he had them all the right length, so the table would be level and not wobble (apparently harder than it sounds).

Because we want the table to be very sturdy, Kyle did mortice and tenon joints for the cross pieces at the base.

 Once they were attached to the sink frame, he put another bar across the base as well. Notice the cut off corners - to avoid getting hurt by bashing your legs on the corner that would have stuck out.

Slats across the base will give it extra stability, and also provide a nice shelf that we can put some small plastic tubs in. This will be where we store cutlery and crockery between uses.

As a request from me, the ends of the big boards at the front and back of the sink frame were left on, and on one side Kyle added a little basket of slats that we can put bottles of detergent and so on in, and the other end there's extra space for plates to be put. There are also a few pieces of dowel across, as tea towel rails.

The front and back boards were painted, as they're most likely to get water on them. Then the whole thing got 3 or 4 coats of polyurethane.

Finally, the very bottom of the legs were capped with a bit of galvanised steel we had lying around to make them last longer. Kyle did up a template in cardboard first, and you can see that the corners are folded instead of cut so that water can't get in through an open corner.

I think the final thing is quite impressive, especially considering that the only part of it that isn't recycled from rubbish was the paint. Even the screws, nails and brackets were from the tip.

Once we have the outdoor kitchen structure finished this will find a semi-permanent home there, with piping underneath to take draining water away to a grey water mulch pit.

The whole thing cost maybe $30 to build, and perhaps $20 worth of paint to make it last longer (we didn't use a whole tin, which we'd bought for something else originally anyway, so hard to tell exactly how much). It took Kyle around 5 days worth of work to build and paint up, stretched into sessions a few hours long over the course of about a month.

Outdoor Kitchen - part 2

(Part 1 here)

After the posts were concreted in Kyle mostly worked on finishing off the toilet block, while my parents and I worked on the kitchen structure.

Dad and I raised the long beams with the help of some ladders. We did find, though, that Dad's careful measurements were a bit out, necessitating climbing up one of the posts and cutting a bit more off:

We clamped them to the ledges we'd cut out on the posts, then put a bolt through each one.

You can see below that the beam furthest from the camera is still a bit higher at one end compared to the one closest to the camera. We figured it wasn't enough to make a fuss about, and it will all work out close enough.

 

We clamped all of the short beams together, and Dad cut lap joints with a circular saw while I chiselled out all the uneven bits so the rafters would fit flush.

Because the roof is tilted (it has to be so rain will runoff) each beam needs to be angled slightly at the end so it will fit flush. They also needed a little wedge chiselled out so they'll fit into the U-brackets at a nice right angle.

It took 3 of us to raise the beams, though by the 4th one we were a bit more confident on the ladders and could do it with two of us.

You get into a routine after a while - lift the beam on one end, slide it into the U-bracket, lift the beam at the other end and rest it on the long beam. Things got interesting with the final knock into place - because there was a slight flex to the poles, and we were putting weight on from one side with the ladders, if we put the ladder in the middle of the building facing outwards as was most comfortable the long beams ended up too far apart and we couldn't get the short beam to hold. So we moved the ladders to the outside, but then they were too close and the beam didn't fit! So we put it in the bracket at one end, then one of us got down and leant against the poles on that side to give it a few more centimetres at the top so it would all fit.

Once we had all 5 beams in place and secure, Kyle exercised his ex-painter skills to raise some ladders and planks for us to fit the rafters.

Scaffolding like this looks dangerous at first, but it isn't really. It takes Kyle about half an hour to set up, checking that each ladder doesn't rock at all, and that each plank is stable and flat. There's quite an art to it, and I'm glad he has experience with it as more than once I've realised the seemingly hap-hazard placement of planks just happens to be exactly where is comfortable to have somewhere to put my feet given the structure we're working on.

I think Dad was skeptical at first, but he seemed to warm up to it.

We did the middle rafter first, as one of the beams was a little bowed. We measured carefully the distance between each beam at the ends, then marked the rafter in those places so that when we fit it into the lap joint we could use it to adjust the beam to make it straight again. Each lap joint got glued, clamped, and nailed.

When you finish something like this, it necessitates selfies from the top of the scaffolding.

The point where short beams attached to the long beams we put nail plates over the top. This way, any force pulling the beams apart puts the nails under shear instead of just pulling them out of the wood. We also stuck nail plates over the lap joints at the end of each rafter, because we had some left over and why not?

Getting the whole frame up took us the better part of 3 days, spread out over more than that due to weather and other commitments. A day of concreting, a day of beams and cutting, a day of rafters. Don't be fooled into thinking you can do it much quicker than that - at first, with this project, I would get so frustrated at how slow everything went, but I've learned to be more realistic with time.

After this, we put corrugated metal roofing on (second hand from the tip, I think it was originally colourbond fencing). Each row took us a few hours, separated over several days because of the weather and having to move the scaffolding in between.

As I write this we have the second of 3 rows up (though only one is pictured here), but have had to take a break due to rain. While Kyle and I return to Canberra for the working week, my parents have said they'll finish levelling the ground under the structure and fill to the edges of the retaining wall (something we'd left undone until now as we needed more drain pipe).

Finally, after all this hard work, one needs a bit of a rest...

(Dad, tucked in on the couch in the motor home)