The Caldera Clone

On the Trangia, it's 24mm.  I used that as my design target in place of doing my own tests.  However, my experience is leading me to suspect that it's not a simple relationship, and it depends on the burner type and configuration.

Some more experimentation is required...

Thanks Kevin (it's all down to the planner )

I used it a couple of time this w/e and it works well, I haven't measured the meths consumption but it seems to use very little. One day I'll measure it or do a side by side comparison with a trangia.

Storage / protection was in a 1.5 ltr drinks bottle cut down, bulky but very light but it was all I had to hand - I'll look for a smaller bottle that'll do the job.

On the holes I was conscious of only being able to make one size so didn't want to go mad, plus there is a fair gap around the handles on the MSR so didn't want all the heat to escape too easily.

Overall it's ideal for a very light brewkit, the material is perhaps a bit too light for a sustained use. If / when I find some thicker alu sheet I'd like to make a more robust one.

Hope it's not too late to post to this thread.

First, thanks for sharing the PS source Captain. I've been playing around with it and have just about figured out the basics. What I'm hoping to do is construct a 2-piece cone so that the unit can be completely contained in my mug. I was thinking of two conic sections that sit one on top of the other with a slight overlap, using two or three paper fasters to hold them in place if required. Alternatively, I might try finger joints at the mating edges though I'm not yet sure how do modify the post script file to do this (help .

On the subject of materials, there are numerous offerings of sheet aluminium on the infamous auction site at fairly reasonable prices. I'm just not sure what thickness to go for. Is 1mm likely to be sturdy enough or maybe even heavier than required?

> Hope it's not too late to post to this thread

Not at all.  Nice to see it's still generating interest.

If you want the latest PostScript code with improved joints, drop me a message.

As for a Caldera Fissure clone, well, I could think about that; it wouldn't be too hard to add a couple of split/finger lines around the middle.  I'll try to get around to it in a spare moment...

In the meantime, note that the pattern gives you the inner and outer radii.  You could add your own joint lines to the pattern by extending the 'centre line' to the centre point of these arcs, and then adding new joint lines in the middle of the pattern, using a measured strip of paper, a drawing pin, and a pen (i.e. you make an ad-hoc pair of compasses...)

> What I'm hoping to do is construct a 2-piece cone so that the unit can be completely contained in my mug

You have seen the Squeezebox Stove, haven't you?

> Is 1mm likely to be sturdy enough or maybe even heavier than required?

I've used 0.15mm foil, and I'd say that's about right.  1mm foil isn't foil at all; it's sheet, and it won't bend and relax like the foil.

Thanks for coming back to me Captain. I wasn't aware Trail Designs had experimented with a two piece cone and I can sort of understand the issues they had. My hope is to join the two pieces with interlocking fingers (similar to your original cone jointing mechanism) and use paper fastners to ensure against seperation.

I'd be very greatful for a copy of the latest PS code and will PM you my email details. I had hoped to figure out exactly how the code to create the toothed join works but despite finding the Adobe PS help files I am as yet none the wiser. Your code draws the fingers inward whereas I would prefer to have them drawn outward to reduce the need for guesswork / trial and error.

I hadn't heard of the squeezebox stove either and I applaud you on your ingenuity. My main concern at first glance is that I would have thought a great deal of heat would be lost due to the combination of the extra large surface area and the spaces for hot air to escape out the top of the structure. I haven't had the chance to read all your posts on the squeezebox yet though so maybe that's already been discussed.

> I'll try to get around to it in a spare moment...

Done...

The Caldera Flissure is born...

Ian has just pointed out a flaw in my variable descriptions that make it unclear...

% normal user print option settings
/fullSize        0    def % print a fullsize A3 page (0/1)

would be better described as

% normal user print option settings
/fullSize        1    def % print the design full size [0/1]

i.e. if fullSize is 0, it will do a shrink-to-fit on the page.  If fullSize is 1, it prints out the true size pattern.

As before; email me if you want the latest pattern.

I recently got round to my first attempt at a two-piece cone using Captain paranoia's excellent Postscript code. For material I used a couple of foil platters from Tescos that cost something in the region of £2.60 for the pair. They were just large enough to construct a cone for my Alpkit Mytimug but I had to use some of the shaped area of the platters which detracted slightly from the overall asthetics but had no effect on functionality.

Inital tests are very positive. Speed to boil 250ml of water outdoors at 3 deg took 5 mins 20 seconds. Compared to the 6mins 30 seconds it takes me indoors using the same same pot & burner on a trangia stand that's a very good result IMHO. 

I've posted a few pictures for anyone that's interested and cannot thank Captain paranoia enough for his help. I am not naturally gifted when it comes to DIY but found the project quick and easy thanks to the template that CP's code generated. 

Pictures here (note that this is a first attempt so excuse the finish. ATEOTD it works):

 Caldera Flissure

> I am not naturally gifted when it comes to DIY

That certainly didn't come across in our discussions; you understood the issues, and had made good design decisions.  It does highlight that the Clone is simple to make; print the pattern, transfer it to foil, and use a pair of scissors to cut it out...  Hole punching and finding the foil are the hardest things to do...

It's worth pointing out that Ian's Clone is actually a a Caldera Fissure Clone; the cone is split into upper and lower halves so that it will fit into his MyTiMug.  A good effort for a first attempt.

Captain 

I'm not sure if this is of interest to you but I certainly found it so.

I decided to run another few tests on the cone tonight and started by adding a small viewing hole as mentioned previously.

I went with 500ml of cold water and a measured 20ml of fuel. The pot came to full boil in almost exactly 11 mins (from the moment I lit it, not when it came to full bloom) and continued to boil for another 3.5 minutes.

I tried another couple of burns using the same measures and got the same results. With the benefit of the viewing window, however, I didn't feel the burner was performing as well as it had with the combined stand/shield I'd been experimenting with prior to the cone. I don't have a picture as yet but this stand is a simple tube made out of the sidewalls from a couple of beer cans with ventilation holes punched in it. Its diameter is only marginally greater than that of the burner.

I let everything cool down, refilled with fresh fuel and water and set up the cone with the beercan stand inside. The stove performed like a furnace and the water came to a full boil in just under 7 mins. The specific times are not that important as I don't know how my burner performs compared to other models but a reduction in boil time of 36% is, for my money, pretty impressive. The heat generated was actually sufficient to melt the edges of the beercan stand which I have used umpteen times without any signs of melting until now.

I think we touched on the merits of redirecting heat back to the burner in our email exchange and I understand the basic science but to see such marked results is pretty impressive.

Hi Ian

 Sounds like your cone doesn't have enough air holes in it? (bottom and top) -accounts for the long burn time?  plus maybe has a wide flame pattern too?

6-7 minutes is pretty standard for boiling 500ml of water with a well-shielded meths burner.  e.g. Mine will do this with around 20ml of meths, but will have gone out by about 8 minutes