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For ti / stainless foils,  I think triangle vents are easier (than holes) to add in.

    For large vents I marked the corners (and centre) with compass
point, drew the vent's outline (fold) lines with ballpoint (on inner side),
then cut from centre to vertices (with a stanley knife, on a slightly opened
work-mate clone), folding the 3 inner triangles in, trimmed, folded the
remaing stem flat (inwards): this means edge of triangle is smooth from
outside (no cut fingers), and perhaps allows stainless steel foil to be
reconsidered (easier
to get/cheaper).

For small square vents (eg input vents) I just  cut between 4 marked compass point corners  with the stanley knife, then used a wood block to try
and smooth/fold the roughness inwards. However, I think it would have been easier if I had also made the lower (input) vents alternating triangles:  <  >  < > etc.

This will tend to stiffen the side of the cone, so it won't form a perfect cone quite as easily; it will create a reinforcing structure.  Whether this is likely to be a problem, I can't guess.

> However, I think it would have been easier if I had also made the lower (input) vents alternating triangles:  <  >  < > etc.

I've got an app for that...

...well, a script, anyway, that I wrote to design a triangulated support for part of my vaned kelly kettle (the Greenalls can, bottom right):

It could be added as an option to the script to allow triangular holes to be used for upper and lower vents...

<fiddles a bit: yes, it's do-able...>

> <fiddles a bit: yes, it's do-able...>

Triangular lattice holes option now added to the script.  Will only generate one row of holes (although there are two rows of alternating up/down triangles in this row).

It brings the code to just over 2000 lines...

I've also re-jigged the conic burner script to allow it to use either fuel volume or height as the basis for the design.  It's a bit more user-friendly, and will draw fill lines to whatever fuel volume is used (in the external jet ring version only; you can't see the lines in the inverted conic design).

>>This will tend to stiffen the side of the cone, so it won't form a perfect cone quite as >>easily; it will create a reinforcing structure.  Whether this is likely to be a problem, I >>can't guess.

The cone wasnt meant to fold, however did'nt notice it preventing ti rollup.

> The cone wasnt meant to fold

Yes, I'm aware of that (not that I've ever suggested folding the cone for storage)...  What I was trying to say is that folded structures (such as the large vents you describe above) act as reinforcement, and these reinforced areas will behave differently to the surrounding metal (in particular, they will be stiffer).  So they are unlikely to adopt the same bend radius as the surrounding metal, resulting in a non-circular cone.  This effect can be seen on the folded tabs, which is why I usually pre-bend the tabs to the radius I want them to adopt when in use.

When rolling up an Al cone tightly, this stiffness means that the foil bends on either side of the tab reinforcement, which has to be sorted out when unrolled & deployed.

If you're using Ti or SS foils, they are very much less ductile than Al, and if you fold them tightly (and then flex or try to unfold), they are likely to fracture along the fold, since they become brittle due to work hardening.

For alu foil, I think just cutting out the triangles would do:

it is harder to avoid sharp burrs on the  (harder) stainless steel and ti foils, folding bits in keeps the burrs/sharp edges on inside/avoids them.

>>> (not that I've ever suggested folding the cone for storage)...

By folding, I meant rolling....I think was there a virtual/implied smiley beside that line...

A while back, a mate brought me back some US aluminium flashing. 

Cones/windshields made from it are robust, but still relatively light.  There is a plastic coating which needs burning/rubbingoff, as it gets a bit smelly as it burns - after a while it goes away.

As a thank you, I made him a clone and redbull open burner to use with a small trangia pan and suitable light ali lid/plate which I had spare. Due to the pan width, a cone fits across inside rolled up plus the burner/fuel measure and pan grab(the latter  fits inside cone).  Plenty room for a J cloth and teabags/cup a soup etc.

The stove performs rather well in the real world - we had an overnighter with a  windy Tor pitch a week or so ago  where he used it for supper and breakfast .

Thanks as usual go to Capt P for providing the script.

Is that a Mini Trangia pan, Mole?  Or the 1l pan?  I've had trouble fitting non-flissure clones into Trangia pans, and needed to use low-profile burners.  Yours looks quite tall; what height and what flame gap?  It certainly seems to fit nicely, and the thicker foil probably means it survives tight rolling better than thinner foils.

It's a nice-looking clone, but the tabs are the wrong way round.  Well, it you rolled it up the other way it would be fine: upper tab should be on the outside.

Always nice to see finsihed clones

I had another script request this morning: now up to 123 users.

That's a 1 litre pan (from a 27 set).  No problem so far with Trangia pan. That's the second cone I've made for one - the first was  the old Heavy Foil last year (when I first posted about the fitting across inside the pan)

 the tabs are the wrong way round.  Well, it you rolled it up the other way it would be fine: upper tab should be on the outside.

Oh - I have always rolled them that way! 

Just seems intuitively easier to assemble this way, the inside 'harder to see/feel' tab being nearer my eyes/fingers.  Is there a structural reason for the other way round?

I don't think the springy flashing would like being reversed again - have to anneal the tab folds to make them not snap  - they end up vaguely curved

(just posted a thread about  my Flissure/modular cookset setup details - which is also inside out!)

> Is there a structural reason for the other way round?

The idea is to keep the tab out of the flame; Flissures have been known to get rather hot at this point (see d3lphi's posts from a while back), as the Flissure joint occurs just where the hot gases hit the side of the clone.  Having a 'thermally isolated' tab at this point may make it vulnerable to melting/softening.

Other than that, no problem.  Since you use fairly low power burners, you probably won't see a problem.

> the inside 'harder to see/feel' tab being nearer my eyes/fingers

erm... there's always one tab inside...

I wonder if it's a left/right-handed thing.

A few posts on a BPL thread resulted in a flurry of activity from the US and other places.  And one respondent had managed to find the Trail Designs Patent.  So I finally get to see what claims they made (and were granted in June this year, five years after the application).

Claims

conic pan support/windshield
- cone joined by some mechanism:
-- magnets
-- ends cooperatively configured to engage
-- engaging ridges (mitre)
- essentially planar
- supports pan under rolled lip of pan
- handle cutout
- intake holes at bottom
-- adjustable option with vent tabs
- exhaust holes at top

split conic windshield
- one or more parts to windshield (upper, lower)
- joined in some way
- split for storage

tabbed top of windshield (cylindrical or conical)
- tabs fold in to close gap between windshield and pan
- tabs may sit under rolled lip
- tabs may touch side of pan

That's about the lot.  There's a lot of background discussion that seems a bit superfluous to me, and a lot of discussion leading up to the claims themselves.  Claim 3 in the patent seems a bit odd, as it seems to be largely a re-wording of Claim 1, and isn't referred to in any of the other claims.  It's interesting that many of the figures in the patent show circular vent holes...  I spotted an obvious typo that seems to have eluded the patent attorney and the patent examiner (a missing comma that changes the meaning quite interestingly...)

I think all features of the clone are covered by this patent, bar one possible loophole that they seem to have missed.  I think the Strata would not be covered.

Of course, the clone script has never been intended for commercial use, so is exempt from the patent anyway...

Oh, and I think it also illustrates just what you can get patented that might seem obvious:

holes at the bottom to let air in

holes at the top to let exhaust out

an opening for a handle

making a cone with a joint of some kind

I think the real cunning bit, worthy of a patent, is the use of a cone engaged under the rolled lip of the pan.  That explicit feature might be an opening for a conical stove sytem with a pan that engages on another pan feature...

Does a US patent have force/effect in the UK? Or would it be a case of registering, and defending, in the UK as well.

Also, I'm pretty sure I've seen lots and lots of people making and selling Caldera Cone type windshields/stove combos? Would that mean a president has been set and the idea widely in use before date of patent registration?

morton moschild wrote (see)

I'm pretty sure I've seen lots and lots of people making and selling Caldera Cone type windshields/stove combos?

> Just because the patent office accepts your money and awards a patent doesn't mean its defendable.

Or that you'd spend a lot of money to defend it.  Lots of dubious 'patent wars' going on in the computing/mobile world at the moment.  Most of which are simply earning a lot of money for lawyers, and acting as 'spoilers': big IP company with a lot of lawyers threatens smaller company on somewhat specious grounds.  Small company can't afford to defend, so have to give in and pay licence fees, or simply stop selling their product.

> has the thread been deleted from bpl?

No, it's the one asking about a stove better than a Super Cat.

> Doesnt the old optimus 91 etc meths stoves count as prior art: the pot edge rests on the (inverted) conic windshield

Possibly; I've never really looked at the prior art, as it hasn't concerned me.  Whoever came up with the idea (the 'first' inventor or subsequent re-inventors), it's a good idea.  Vent holes, a joint and handle cutouts are blatantly obvious, IMO.