Jul 9, 2013 at 12:50 pm #1305181
Maia JordanBPL Member
@maiaLocale: Rocky Mountains
Companion forum thread to:Jul 9, 2013 at 1:52 pm #2004183
Thanks for that detailed article.
If I understand well, the final design might be a chinese titanium head (FMS 116 T ?) with custom legs, hose and valves. That sounds good ;) !
I just worry about abandoning the "universal" self stable 3 leg support design.
A central support is great on a flat ground but not that great on a rocky terrain, one foot among the 4 (or 6 according to the last picture) won't touch firmly the ground.
Will the 3 aluminium legs be flexible enough to allow enough freedom of movement ?
SamuelJul 9, 2013 at 2:20 pm #2004194
Michael GillenwaterBPL Member
@mwgillenwaterLocale: Seattle area
Actually, I think it might be a typo.
-184 C should equal -299.2 F
or if you meant -363 F then that equals -219.4 CJul 9, 2013 at 3:05 pm #2004206
> Actually, I think it might be a typo.
> -184 C should equal -299.2 F
Chuckle – yes!
I think BPL added the imperial temps as they were not in my source. +184 C = 363 F. The web guy missed the minus sign.
I will email him and get that fixed.
Cheers/thanksJul 9, 2013 at 3:16 pm #2004213
> I just worry about abandoning the "universal" self stable 3 leg support design.
> A central support is great on a flat ground but not that great on a rocky terrain,
> one foot among the 4 (or 6 according to the last picture) won't touch firmly the
Yes, there is a trade-off here.
Remember that this is a winter stove, so it gets used on snow sometimes. It also gets used on rough bumpy terrain, lumpy snow grass, sloping rock, even sand. The trad 3-legs design does not work well on any of those in my experience. I seem to always use my little 3-ply stove base, first getting it level and solid.
In addition there is the skittering 'UL stove' problem which also needs attention. I don't want too much 'freedom of movement' with my stove – that gets dangerous. I find the micro-stakes very reliable in stabilising the stove. Part 3 has more details and alternatives here.
Summer uprights have a nice heavy canister as a base – lucky them!
CheersJul 9, 2013 at 3:23 pm #2004217
Michael GillenwaterBPL Member
@mwgillenwaterLocale: Seattle area
No worries. Although that does not mean the minimum operating temperature is 184C?
More importantly, I'm at least waiting eagerly for the final installment and where to click purchase. I think you have earned another doctorate in stove design and manufacturing here. Impressive work.Jul 9, 2013 at 3:39 pm #2004222
> Although that does not mean the minimum operating temperature is 184C?
It means the minimum operating temperature for the HOSE is MINUS 184 C. That is down at the boiling point of liquid oxygen (-183 C). You don't want to go there.
CheersJul 10, 2013 at 7:43 am #2004412
Michael FlanaganBPL Member
@mikelawLocale: Long Island
Not sure if you want a design committee comprised of readers but I'll just throw in my two cents: Why not have the "stove stakes" hinged somewhere on each leg? That way there's no chance of losing them and they could be folded into the leg when not needed (if ever). The stove stake could also serve the purpose of acting as a leveler of sorts by varying how much you push the stake into the ground if you're cooking on uneven ground or on a slope.
I don't think you can make the design dependent on their use since the stakes could only be employed into dirt and not rock.
Just a thought.Jul 10, 2013 at 11:59 am #2004488
Doug JohnsonBPL Member
@djohnsonLocale: Washington State
I am loving this series- thank you Roger!Jul 10, 2013 at 2:58 pm #2004539
Hi Michael F
> Why not have the "stove stakes" hinged somewhere on each leg?
Neat idea, but how? Ideas from anyone welcome.
> I don't think you can make the design dependent on their use since the stakes could
> only be employed into dirt and not rock.
I agree, which is why they are separate at present. More on this in Part 3.
CheersJul 10, 2013 at 9:22 pm #2004693
"stake" in the form of a small eyebolt but not threaded; riveted to each leg with plastic washer(s) for friction fit; rotate into downward position for use as stake; rotate into retracted position when on hard surfacesJul 10, 2013 at 9:40 pm #2004699
Hum … I will have to think about that one for a bit. Turning 1.6 mm Ti or Al wire into an eyebolt sounds a bit tricky, and rivets and washers add weight too.
Deep Thought required.
CheersJul 11, 2013 at 4:24 am #2004722
J CBPL Member
My FMS-117t does not have the body touching the ground. Seems to be something they changed.
I am thinking about modifying my 117T, any ideas about how to get the hose out of the base? Does it involve the tiny screw in the base?Jul 11, 2013 at 7:13 am #2004751
Jerry AdamsBPL Member
@retiredjerryLocale: Oregon and Washington
If the body touches the ground, then you now have 4 points touching the ground so it can be wobbly on slightly uneven ground. "Three legged stools" have advantages. But if the 3 legs are springy it wouldn't matter.Jul 11, 2013 at 2:54 pm #2004906
Yep, probably a tad heavier if attached. But you won't lose them, and they would be where you need them when you need them. Could also be laser or waterjet cut out of sheet stock.Jul 11, 2013 at 2:59 pm #2004909
> But if the 3 legs are springy it wouldn't matter.
Yes, it's a trade-off. 3 big solid legs would work fine – but they would be heavier.
I do have a different sort of leg which does not have the centre support. It works, but the springiness seems a bit chancy in comparison. The wobble is definitely obvious.
CheersJul 12, 2013 at 7:23 am #2005138
> I think BPL added the imperial temps as they were not in my source.
I had planned to write a note of thanks. I noticed the article had unit conversions and other articles had not. I think it is a nice addition.
When I make notes, I include conversions. It takes me some time but saves many man-hours of conversion time for the other people.
Maybe the BPL-guy with + in his eyes will read this; it is his thank you.Jul 12, 2013 at 8:00 am #2005145
> I do have a different sort of leg which does not have the centre support. It works, but the springiness seems a bit chancy in comparison. The wobble is definitely obvious.
This might be a little difficult to describe. I am thinking of the cheap type of photographic tripod that has the center supports to stiffen light legs. Well, very expensive video tripods have these supports as well.
Anyway, there are the three legs, of course, and these make it possible to always have good contact with no leg/earth wobble/totter.
About 2/3 way up the leg are cross members to connect the three legs to a central support. These cross members are hinged and fold out of the way when the tripod is collapsed. The central support could be your burner tube.
I suppose little rods could run from each leg to the burner tube/housing. I don't think a hinged rod that remains in place, as with the photo tripod, is practical. The rod may be hinged on one end or come free altogether. On the burner end, there could be a little dimple or receiver for the end of the rod/wire. Securing the leg end of the rod is an exercise. Threaded sleeve magically attached to the side of each burner leg?
I think just running the rod from tripod leg to leg without meeting in the center would add stiffness. This might be easier to implement.
Running around the perimeter allows at least two methods of implementing the idea. Three rods could be used to run between the legs without heading to the center. I wouldn't position them 2/3 up. Maybe halfway up.
The rod could slide through an opening in one leg and into a receiver on the adjacent leg. The opening in the first leg could be a threaded sleeve (attached with any remaining magic) that the rod, threaded at the end, could be screwed into. Attaching the threaded sleeve to you stove leg probably isn't practical. Tapping the leg itself probably wouldn't be enough simpler.
What might work is to make a wire loop pre-bent for the triangular shape of the tripod. The wire could be thin. It just needs to be strong enough to put tension on the legs. Each stove leg could have a little groove for the wire to seat in. The two ends of the wire could be joined and tightened by a couple different ways. Some kind of tiny turnbuckle type arrangement. Whatever.
[the whatever would need to be something that could be finger tightened easily enough to properly tension the hoop. for this reason i don't think a typical turnbuckle that requires a wrench is practical. the user doesn't need a little tool to deal with. I can't imagine a micro turnbuckle has a built-in lever..? maybe little turnbuckles with flattened edges exist. the turnbuckle equivalent to a wing nut.]
If it adds enough stiffness and allows 3 points of contact to be viable, it might be worth the trouble. If the burner housing can be smaller because it doesn't need extend to the ground, that weight saved would offset the connector rods or wire.
It does add to the assembly for the user. Increased fiddle factor. Most stoves just fold open… The hoop wouldn't always need to be used. It could be lost or not used when it should be. It creates a bit of room for user misdecision. Error. Pegs a user must place to secure a stove are also a thing they could lose or fail to use. I guess it depends on the user and the number of warning labels on the packaging :^)
I don't think I would worry with Deep Thought. The answer is 42. If the tripod legs are wobbly, I wouldn't give up on the benefits of tripod design. I would consider stiffening them. If the legs flex in and out, use a wire hoop to pre-flex them in and prevent the out…Jul 12, 2013 at 8:43 am #2005157
> …used on snow sometimes. It also gets used on rough bumpy terrain, lumpy snow grass, sloping rock, even sand. The trad 3-legs design does not work well on any of those …
Three legs always work well for a stable platform. Without independently adjustable legs, the ground needs to be fairly level, of course. So the average slope of any surface can not be great. However three legs will always form a stable connection with surfaces that are not uniformly level. If three legs don't work well on soft surfaces, they need a broader foot. [or the board you use, of course. i agree boader feet on stoves isn't really desirable]
I guess it would be pretty easy to create a firm enough surface with snow. Unless it is very dry. The skitter factor remains. Shifting sand is hard. Is this sand enough to make dunes that are difficult to walk on? I haven't been to any classic 'dune' type deserts where there wasn't some rock reasonably nearby. I have only been around little dunes with safe haven from the spice worms. Dry sand only… I might put a cloth under the stove legs to distribute the load. The fabric would need to be reasonable stiff to be of any use and might not be a good idea if wind could get under it and lift it and the stove. If I worked on soft surfaces often and it really was a trouble, I might try baskets of some sort. They work for skiers. Probably not… A tripod would sit on the top curved surface of a rock. The rock doesn't need to be level. The radius/dome of the top just needs to not exceed the area/arc bound by the tripod legs. Or however it should be described.
I guess I am pro-tripod because I use one regularly with my camera. While it has independently adjustable legs and allows more freedom in site selection, I have set it up on just about every type of surface someone is typically going to find acceptable for cooking. Yeah, I have had to stamp down snow to prevent it sinking.Jul 12, 2013 at 11:16 am #2005240
Thomas RaylBPL Member
@traylLocale: SE Tx
I like the thought but I'm wary of tiny, easily-lost, single-use parts. Personally, I also am not a fan of "shepherd's crook" pins/stakes: I too often find hard ground requiring stakes to be pounded in (room for another whole thread on this one!). My personal favorite is the MSR Groundhog stakes — a three-flute straight stake with a cord loop at the top. Relevance? How about forming the stove legs with a slight nub/bump/spur or something at the TOP of the outer leg ends so a full-size stake (shepherd's crook or straight-with-loop) can hook over it. Take extra stakes of what you're already using and you have inherent back-ups. Granted, not necessarily the lightest, but each can judge the feasibility on their own. And the stove design itself perhaps stays a bit "cleaner".Jul 12, 2013 at 2:37 pm #2005299
> Could also be laser or waterjet cut out of sheet stock.
Yeah, I got a price on that. Was over $5 per leg. Um ….
CheersJul 12, 2013 at 2:42 pm #2005303
Interesting ideas, but please remember the target weight for this stove is UL. If it weighs over 100 g that is clearly far too much. Under 90 g would be nice.
But keep with the ideas, please.
CheersJul 12, 2013 at 9:12 pm #2005433
Thinking about this I have to ask how much of the "skittering" issue is due to fuel line stiffness and how flexible can you get the fuel line to be while retaining sufficient durability and heat resistance? Having never used a stove as light as what you are playing with (few have, only those who make their own), I can only extrapolate from the stoves I have used, which, though significantly heavier, also have significantly stiffer fuel lines, and will move around pretty easily until a full pot is sitting on them. So I can see the issue, but I frankly hate the idea of tiny separate pieces to keep track of, and trying to manipulate them with gloves on on a frosty evening when I want my dinner NOW makes me think a couple ounces more stove is worth it to avoid that.
Putting it another way, if getting it that light requires making it too fiddly then it ain't worth it.
So then I wonder what can you do that keeps the weight low and reduces the fiddle factor. For those who like the stove base idea, I wonder if attaching the stove to the base is enough to counter the wandering urges of the stove, and if so, what method of attachment can be simple, reliable and glove-friendly?
I'm also wondering about the nature of the problem – is it only without a pot that you had issues, or was this still a problem with a pot on the stove? And is leg stiffness a contributing factor? Inveterate designers and tinkerers are dying to know.Jul 13, 2013 at 3:37 am #2005460
> much of the "skittering" issue is due to fuel line stiffness and how flexible can you
> get the fuel line to be while retaining sufficient durability and heat resistance?
The fuel line is pretty flexible. Not 'extremely flexible' – that requires a hose which cannot take the temperatures. I don't really think the hose itself is the problem.
Much of the problem, imho, comes when you turn the canister upside down. If the stove itself weighs 50 g, it is extremely easy to jiggle it a bit by moving the canister around. Or you can just be a bit clumsy and accidentally knock it with something. I am good at that.
> tiny separate pieces to keep track of, and trying to manipulate them with gloves on
> on a frosty evening when I want my dinner NOW
That does not seem to be a problem for us/me. We put the tent up, get settled, and then I start cooking. At this stage I generally do not have any gloves on: a bit dangerous imho when playing with a stove. If my body is warm and i am out of the wind, my hand is OK.
So for me there is no problem 'manipulating' the stakes. It only takes seconds to stick them in. They travel in my cooking pot with the stove anyhow.
> attaching the stove to the base is enough to counter the wandering urges of the stove
Actually, this could be so. There are more details on this in Part 3, which should follow soon. More experimenting might be a good idea here.
> is it only without a pot that you had issues, or was this still a problem with a
> pot on the stove?
I THINK it is only a problem when the pot is not on the stove. Once you have dinner on, things are much more settled – in my experience. This needs testing. :-)
CheersJul 15, 2013 at 9:47 pm #2006534
Kevin ManleyBPL Member
I love the obsessive attention to detail here. Can't wait for the finale!
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