DSR (Double Shoebox Rocket) revisited

So it’s getting pretty cold outside, and when I built the last version of my stove I promised a breakdown analysis after I had used it for a season and had a chance to sort out my experience. Now that I have rebuilt the beast it seems the time is here to write about it.

First I would say that overall it performed pretty well, the weakest part of the thing being the door. The visions cookware lid I started with did work, but I would not plan on using such a thing except in a pinch. Eventually the first one cracked, primarily from physical shocks because it really does get too hot to handle at times leading to bumps and drops, and once hot it will use any excuse to crack.

Over the three to four month life of the stove there were numerous tweaks and while the final product worked, it would never have lasted another four months without many more overhauls.

My building style was primitive, using lots of clay and perlite, which was always sufficient in the original rocket stoves I built, but with the more compact and intricate design of the DSR bricks are really the way to go for all vertical surfaces, not just inside the firebox/batch box. Also bricks give an element of speed to the construction, and the finished product is structurally more stable. With clay walls on much of the old stove, cracks were commonplace, and I often worried about them just falling completely apart. If you do want to use clay, make sure it is a continuous mold type process. Forming one wall one day and then adding to it or building an adjoining wall the next does not give a reliable bond.

The water tank was the next area of interest, primarily because it was an issue I had to revisit many times, especially after one spectacular failure. My theory that pex could withstand temperatures in excess of water boiling was good only to a point . Hot, therefore soft, pex under extra pressure will blow out. Use all metal fittings inside the heat chamber and for a distance outside the chamber, and of course, when heating water, always have the system open so steam can escape safely. Pressure relief valves are a real good extra insurance in case one forgets to depressurize the system.

Soot was present everywhere the exhaust touched , except the parts that got the hottest in the burn chambers. The thought occurred to me that I had basically turned the entire downstream part of the stove where heat was extracted into a creosote trap, and future builds will have to accommodate an easy access for periodic cleaning.

Future builds will also need to be more efficient, and since start up and cool down phases of the burn are the most problematic, shortening those periods compared to overall burn time will be a major concern. Quality dry fuel will become a major goal for operation of the next iteration of the stove.

Recently I read more about the continued development of the DSR II and it has taken some interesting turns. I’m not sure I will be using all the developments, but at some point I will likely be adding a short riser at the back of the firebox. That will likely wait for me to get some ceramic fiber board, so for now I’m just using the old DSR design.

original visions lid, the crack is visible on the left side running under the handle, and I continued to use it till it cracked into several smaller pieces later on
this hodge podge is the water tank enclosure As the winter closed in, my hurry to get the stove functional meant many makeshift connections and very iffy seals. The forced draft kept a negative pressure inside the stove so leaks weren’t really a problem, but it would always be best to have everything tight as a drum

I broke down and bought a 10×10″ piece of neoceram glass–expensive (50$) but a good investment
this is before the old stove was finished being built
taking the stove apart, note the soot in the oven chamber but not the firebox area
getting a start on the base of the next DSR, note the exhaust has been extended and turned toward the left in preparation for the changed position of the water tank and the exhaust exit from the stove

I was a bit remiss taking pictures as I dismantled the old DSR, and obligations elsewhere meant much of the new construction was not overly documented, but look at the next post to see how the new DSR changed.

4 thoughts on “DSR (Double Shoebox Rocket) revisited”

  1. Hello Bob,
    Since several months I am following donkey, wheaton, Peter van den Berg etc. They talk about the double shoebox and there is even made a video of it (Allerton Abbey) and I think it is all beautiful and I would like to make such a thing with an oven and heated thermal mass.
    Peterberg even posted a sketch-updrawing of the double shoebox but it is without oven.

    Before trying to make it I read the Wisner’s-book, just to understand a little bit more.

    And then I discoverd your site with this DSR that you demolished and rebuilt again? And you start talking about the fact that DSR1 was abandonned by Peterberg, but that it didn’t matter for your purpose at that time and then later on you write that you recently read more about the continued development of the DSR II and that you will use some of the changements etc…… and I am curious wich changes you will use and why.
    I tried to find information about DSR2, but I can’t find it.
    Paul Wheaton also publishes some nice foto’s of the making proces in wich I see (I think) an air inlet down at the right etc.

    I am puzzled…

    I thought I’d give it a go to write you and just ask. Because the way you made your DSR seemed to be the most rudimentary/straightforward (I don’t know the word) without to much industrial things. Later you explain why you will change to firebricks and it seems logical to me and your way of building/thinking seems to be close to the way I would like to build things.

    Maybe you are able to answer my questions (above) and maybe you even have some drawings, foto’s of the making proces etc?

    I am so eager to start building, but I also want to make a nice thing that works (A cooktop with oven and eventually a heated bank that is rather efficient).

    Hopefully you are able to answer my questions,

    best regards,


  2. Hello Bob,
    thank you very much for your reply. I was curious to here from you, but I think 4 days isn’t that big of a delay 😉 I am very pleased with you replying!

    I know donkey’s forum (that is how I found you) and for some reason I then didn’t find the thread but 3 days ago I found out about DSR2 being developed and the outcome.

    As a result of this info I got the idea idea to use the DSR2 as a motor for the cooktop that was made in Allerton (and what you made), with DSR1 as a ‘motor’. And I wanted to know if that woud be possible. Therefore I placed this idea (drawing included) at a dutch forum where I hoped Peterberg would read it (Dutch is my language). His answer was that he doubted if the DSR2 would give enough heat to cook on and he advised me to look for a proven design since my experience in stove building is almost none.

    But his answer makes me even more curious. First of all I didn’t understand why it would not heat enough to cook on. What is your experience?

    The DSR2 cooktop, as said before, I want to make with an oven and a bench all separately manageable; when I don’t need the cooktop I would insulate it (like you with a ceramic fiber blanket?) so the heat goes either to the bench or the oven. There will be a lot of ‘tubes’ with valves to direct the heat.

    As a profession I build with clay, lightstraw and wood and I know masonry. Do you think it is a big deal to built this? And most important; do you think it makes sense to try and build this? I want a thing that heats a room while cooking or just after that.

    I understand that your idea is to insulate it from the inside? Why not from the outside? like you already do? ….if I understand it well…..

    Curious to hear from you…take your time 😉

    Best regards,

  3. Hello Bob,
    Because of your advice I dicided to give it a try and -if its true that the price for his plans ánd help (eventually) is 80 dollars- I am going to contact Walker Stoves.
    Since my experience with building this sort of stuff is almost ‘0’ I think I’d better build a thing that has proven to work. Aside I can always experiment.

    I am excited to start.
    Thank you very much for your effort. I already learned a lot only communicating with you. Thank you.


    Maybe you would like to know, but I never receive emails that you posted a reaction (after spam controle). I can only see them when I go to your site.

    1. Hi Bob,
      I bought drawings from walker stoves. Very nice so I don’t have to nvent things myself ;-)…..and the nicest part of it is that Matt (Walker Stoves) has a stove chat every wednesday! Very, very interesting and a lot to learn from. So nice he does this.
      And you know what? There was a question if you could cover the CFGlass-top with some insulation if you would want to bring as much heat as possible to the rest of the things to be heated (bench, watertank…..) Matt couldn’t answer the question because he didn’t know. He would be afraid the glasstop would not be able to handle the heat. Since you have done that (You did didn’t you?) you are the expert on this topic. Can the glas cooktop handle the heat?

      I am going to build the masonry heater of walker stoves. Using the IFB for the core and clay around it. I think it will eventually look like your stove. 😉
      Keep you posted

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