Work Update

[Work Update]: Fiji Fuel - Buka Stove 5.0 - July 2018

Fuel II has worked on creating a new prototype of the Buka Stove, currently named as version 5.0. A number of issues were discovered during the first week of the July project, regarding the dependency version 4.0 had on refrigerant tanks that were sourced free from different companies, and how reliable it would be to scale up production of the Buka stoves to fulfill a larger demand. The appearance of the version 4.0’s were also inconsistent, and had poor spot-welding that we would preferably like to eliminate to improve consistency, appearance, reduce labour costs and generally improve efficiency in production and preventing breakages.

We got to work on our first monthly goal, which was to create a new prototype of the Buka stove and test with 10 people. Firstly, Teich (TL) conducted a prototyping workshop where we ideated a range of possible prototypes based on the "10 design principles of a rocket stove" from Dr Larry Winiarski. Feedback from existing customers was also taken into account for the new design, and are further being explored when empathising with prospective and existing customers. The main aim was to remove reliance on refrigerator tanks or any other non-scalable material.

We decided on a hexagonal body, that would most replicate the trusty cylindrical design used in previous Buka stove designs. The new prototype would ideally be laser cut from one or two metal sheets, folded and then be held together by pop rivets where necessary. To minimise labour costs and simplify the manufacturing process, the 5.0’s legs have been designed into the body instead of separately attaching them.

To again reduce materials, it was decided to remove the pegs holding the grate and to also integrate that into the design. Folding the side of the body under to hold the grates will be a simplistic way to hold the metal grate and remove effectively. An ashtray was highly requested by existing and prospective customers, therefore we will be offering an additional ashtray with the stoves.

Finally, to regards to removing welding in the 5.0, the top of the inner chamber will rest on the outside chamber, that slopes upwards instead of downwards like in the 4.0. We hope that this will ensure more weight will be supported where the two chambers meet. Initial weight testing shows that the prototype can easily support 10kgs.

On Wednesday (18/7/18) we finished making the prototype for the Buka 5.0. Over week 2 we obtained materials, deciding on zincalume steel for the entire model as it was the only type that could be sourced locally at the current time. The 5.0 prototype was made from two templates cut from a single sheet of metal, using folds and cuts, riveted in place for stability. In future, we hope to make it with stainless steel as it is more heat resistant, reliable, sturdier and longer lasting. There was discussion of whether or not the inner chamber will remain cylindrical or follow the hexagonal shape the 5.0’s outer chamber resembles, however Fuel team I will be looking further into this with supply and costs in mind.

There were a few issues we have noticed in the prototype. The vents have been made where the inner chamber lip folds over, and is folded back to let the smoke escape. This is an effective but unsightly solution so further testing and ideation will be needed to assess whether we need to create a different ventilation type for a finalised version. Another issue is that the prototype has 6 legs, whereas having 3 points of contact would be ideal for stability. The use of chicken wire in the model is not viable as well, as it is not strong enough to support the wood nor act as a door for the firewood to lean on. The idea is to have the original metal grate used, and extended where the door sits in the 4.0 to act as a ledge for the firewood to lie on.

We now aim to put the first 5.0 prototype to test. We will test  to not only determine the relative efficiency of the stove, but to be as repeatable as possible, such that following teams can redesign the stove and run the same tests to see whether or not improvement have been made. Qualitative tests with potential customers will be conducted next week to gain their feedback and thoughts on usability and design.

edited on 6th September 2018, 00:09 by Justin Hakeem

Alexander Teicher 11 months ago

Would be very interested to get your thoughts on the new design.

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Cris Birzer 11 months ago

1. The cardboard will probably burn!
2. (seriously), be aware that sheet metal can be an issue for manufacturing. If the wall thickness is too thin, the central section will eventually burn through. If the wall thickness is to thick, then folding it is difficult. It is typically easier to roll than fold.
3. You could also look at just importing the Berkeley Dafur Stove (BDS) from India, assemble it in Fiji and sell that under licence.

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Scott Jucius 11 months ago

1. Assuming you will remove the current sharp edges, do you see any other safety issues for customers by using sheet metal? e.g. If an object is dropped on the stove, will the shape of the stove change such that the sharp edges of the metal stick out.
2. With the use of riveted sections and stainless steel in the future, this may instigate crevice corrosion due to the Fiji environment.

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Alexander Teicher 10 months ago

Hi Scott,
Both very valid points! For safety, both a manufacturing and user safety guides are being drafted and we don't see any major risks with the sheet metal. Tim may be able to add more detail here.

For corrosion testing our intention is to have at least one new prototype in the production materials made to be left until summer to assess how well the materials weather. We are also looking into organising case studies with customers that can test durability among other things.

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Tim Tsiflidis 10 months ago

There are some standard health issues when manufacturing the stove ,fumes,sharp edges etc..But for customer usage not really.The prototype looks pretty thin but I have literally jumped on it and no dents were formed.The sharp edges are present due to the fact that we had to manufacture our 1st prototype ourselves.In addition,with further testing we will be able to determine if alterations to the surface will occur after applying lots of stress over time (constantly having large sized pots on it and use of stove for cooking),but based on the properties of the metals that we are using that should not be the case.I hope I have provided some insight,let me know if you have any further questions

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Justin Hakeem 10 months ago

Status label added: Work Update

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