Wind screen for Optimus Crux

[Bruce .]

Anybody have any good ideas for a wind screen for an Optimus Crux?
Thanks

[Drowned Lemming]

If you go to “Selecting a Canister Stove for Cold Weather Backpacking
Part II” and look at the photograph directly under the subheading “Titanium Pegs” you will see the sort of arrangement I use.

Closed cell foam base, the same diameter as the pot being used, with Velcro glued to the circumference.
Aluminium foil, with Velcro glued to the bottom edge. For the Crux, the foil is obviously taller than for the Windpro in the photograph, but I use the same base.

Total weight 1.5 oz.

As discussed on other threads here, monitor the heat of the cartridge, but I have never had one get beyond warm (and I cook food, not just boil water).

This setup is effective and has the advantage of slightly warming the cartridge in cold conditions, improving efficiency – but if I know it’s going to be cold I’ll take the Windpro and invert the cartridge.

[Bruce .]

Thanks for the tip. I looked at the photograph, and if I understand you correctly, you wrap the canister & stove in this type wind screen? i’ve read a lot of warnings not to do that, so I want to make sure I understand what you’re doing.

It’s good to hear that you haven’t had any problems overheating. I like to cook on the trail as well, I don’t just boil water. I’m converting from my MSR whisperlite to canisters, so it’s all new to me!

[Drowned Lemming]

Yes, cartridge and stove wrapped around for about 2/3rds of the circumference. This leaves a space for the pot handles and to check the temperature of the gas cartridge.

Stove manufacturers don’t recommend this, because they are worried about the claims if someone eventually achieves a BLEVE (Boiling Liquid Expanding Vapour Explosion). However, in the real world this set up works!

It would be interesting to see the accident statistics by stove type – I have seen a fair few petrol stove dramas, but never one with a gas stove.

[Douglas Frick]

>I have seen a fair few petrol stove dramas, but never one with a gas stove.

I Googled for canister stove explosions and could only find idiots-throwing-canisters-in-bonfires stories.

[Mike Storesund]

I have always been leery of placing a windscreen around a canister stove, in fear of it overheating. I don’t like unwanted KABOOM’s!
What I have done is made a windscreen out of aluminum flashing to enclose the pot with about a ¼ inch space between the pot and screen all the way around. I fold over each end in opposite directions so they can clip into each other. I then suspend the windscreen from the lip of the pot by using 4 paperclips and inserting the opposite end into the 4 holes I made every 90 degrees on the windscreen. I bend the paperclips similar to ‘S’ hooks. I adjust the windscreen so its top is just below the handle of the pot and mark where I need to trim the windscreen so its bottom is just above the stove’s valve.
The windscreen rolls up and fits inside the pot and the paperclips stay in the inside of the pot as well without bending them. I also bring a couple extra paperclips just in case.

[Stephen Eggleston]

I use a simple windscreen made of heavy duty aluminum foil for my Crux stove. Basically I measure a piece of foil tall enough to reach from the ground to the top of the pot(sitting on the stove and canister) and wide enough to leave some ventialtion gap around the pot. I double this measure so that I can fold the piece in half later. I then cut the piece, fold it in half and use a hole punch to put airholes around the bottom edge.

I place the foil around the pot and stove with a vertical opening wide enough to adjust the flame and check the temp. of the canister with my finger. The width of the opening varies with the ambient temperature, wider is warm/hot weather and more narrow in colder weather. I use rocks or the pot handles to keep the edges of the opening from blowing around in the wind.

This is very simple but effective windscreen. And of course, the disclaimer: ‘disregard manufacturer’s warnings only at your own risk and discretion’

[Bruce .]

Thanks for all the tips.
I’ve used white gas stoves for years. Only had a couple of flair up problems, but have never heard of a problem with canister stoves. I can certainly see the danger in overheating a canister, but it would be interesting to see a study on just how far one can go before creating a dangerous situation.

Sounds like the kind described here should work fine – as long as I keep a wary eye on the canister temp!
3pinner

[Bruce .]

Here’s a link to a really interesting option.
has anybody tried this?

http://jwbasecamp.com/Articles/KiteScreen/index.html

Click on the link for Operation in the Wind Then on “Tom Wood’s Kite Screen”

[Marius Bunes]

Hello,
I’v run into the same problems – the Crux is not so easy to build a lightweight, safe, stable and yet simple windscreen. Maybe the simplest, lightest and safest option is to use a modified MSR Windpro stove and a perforated BMW Ti foil windscreen. My solution for the Crux is safe, relatively stable, effective and in my wiew simple. The crux has a spring-loaded sliding aluminum cylinder to lock the burner in upright position. It can be used to support a light aluminum baseplate. I used 0,5mm round aluminium plate slightly larger than my pot. (evernew, 0,9l)I made a cutout slot large enough to fit the inner tubing of the crux stem – very much like the link to Jim Woods windscreen in the last post. The outer edge of the plate is bent upwards, to make a small rim of 1-2 mm height. To provide ventilation and reduce weight, I’ve made lots of perforations. All edges is rounded and polished so I do not ruin lightweight nylon gear. A BMW Ti foil is cut to fit the pot, and is kept in place with a pair of paperclips. Heat from the burner is shielded from the canister. The metal walls shields wind and conserves heat for efficient cooking. During use, especially on full heat output, the foil can sometimes glow red-hot. This seems to be of no significance and it cools off in few seconds after the heat is shut off. It is not “bombproof”, in my opinion, only Trangia cookers has decent bombproof windshielding. They are too heavy for my use. I wish I knew how to post pictures, then I could write a DIY description.
As with all hommade windscreens, the disclaimer should read something like, this works for me, try it yourself at your own risk.
Marius, Norway.

[Marius Bunes]

Sometimes, images speak louder than words.

The aluminum plate could have been circular. Mine happened to be just a bit smaller. I used 0,5mm Al sheet, scissors, 8mm Ø HSS drill, 100-grit sanding paper to remove sharp edges.

The slot must fit exactly on the smallest diameter of the spring-loaded aluminum locking tube. Somewhere betveen 12 and 13 mm should be ok.

BMW unperforated Ti foil and two paperclips goes on top of the baseplate. I needed to cut away some foil to provide space for the pot handles. The windshield is so light that it does not affect the spring-loaded locking tube. The foil is stiff, and rolls small without “memory”. But sharp folds in the foil stays, so take care.

The windshield is kept in place by the weight of the pot with its contents. I have not tested the heat buildup on the canister with thermometer. My field experience is that I cannot feel heat buildup on the canister with my hands. The windscreen has never fallen off during use. I regard it as fragile gear, and treat it as such.
Weight? 23g on my scale. (=0,73oz)
Marius.

[Bill Fornshell]

Crux on Legs:

[Marius Bunes]

Fornshell shows excellent images of what I think may be the most versatile and safe canister setup for the least weight cost. A canister with flexible hose can be used in cold conditions, as described in recent rewiews on BPL. Lowering the overall height lowers the gravity center of the “cooking tower”, and makes the whole setup more stable. In-tent use is thereby made safer. (this will never be reccomended but often done in bad weather anyway) Windscreens is no longer a problem, standard MSR/Primus Al foil types can be used safely. My lightweight choice would be perforated Ti foil. I think the MSR windpro might be a little lighter than Fornshells setup, but it might be more cost-effective to buy this tripod. I got one from VauDe, but have used it little.

[Dale Wambaugh]

“http://jwbasecamp.com/Articles/KiteScreen/index.html

Click on the link for Operation in the Wind Then on “Tom Wood’s Kite Screen” “

I always carry a large garbage sack and my first thought was that you
could make one of these kite wind screens by cutting a cross section from the garbage bag– like making a rubber band from an inner tube. Add a few sticks and you have one. A 4′ length of aluminum foil and paper clamps would make a good quick and dirty version too– certainly easy to tuck away in your pack to use when needed. As I’m writing this it occurs to me that a section of space blanket and some duct tape could be used, which are both items I carry all the time.

[Roger B]

Bill I am continually impressed with your gear making skills. Can you elaborate a little more on your legs, stove legs that is. As a crux owner I am tempted to make a set.

Thanks

[Brian James]

Marius, the Crux won’t work in the cold using the inverted-canister method as described in the review. The problem is that the crux doesn’t have a preheat tube, meaning that you’d be delivering liquid propane to the burner head. Unfortunately :(

Now if someone would just invent a retrofittable preheat mechanism for a remote-canister crux setup…

[Bill Fornshell]

Thanks Roger but I had a little help from some friends on the “legs” attachment device. You can see more about it here.
“New Stove Stuff direct from Japan”

One day I do expect to make a set of legs out of Titanium to reduce some of the current stock weight.

Vaude does have a product that looks like this one but I don’t know where you can buy Vaude stuff in the US. Vaude has a few other things I would like to have. I will do some searching next week and see if I can come up with a place to buy there stuff here.

[Marius Bunes]

My mistake, of course a preheat tube is necessary for cold weather operation. The Crux would probably not work so well.

[Erik Basil]

As a happy owner of a Crux that's been doing me fine, the one issue I've had is the wind issue when I can't set up in a sheltered cooking location — and I've got two burn-damage spots on my HE Weekender's fins to prove it.

My solution for a recent trip was to make a windscreen out of a "chicken pot pie" foil pan. I thought that the inverted cone shape would fit nicely to shield the sides of the burner and then funnel the hot gasses up and through the HE fins while allowing a good draft of intake air from below.

I went to KFC and enjoyed a chicken pot pie (since store-bought pies now have microwave safe paper pans) and then took the nice aluminum pan home instead of to the trash. I cut the bottom out, then slit the resulting "ring" so that I could fold it down smaller to fit inside the Weekender pot. Using an X-acto, I cut three flaps in the foil, to foil inward, on top of the Crux's three pot supports, thereby suspending and securing the screen in a location that only shields the burner head and gives about a 1/4" gap around the edge of the pot –only really covering the fins and another 1/8" of the pot base. Finally, I cut a slit and hole in the former pan base, so that I could put that under the burner head and either reflect heat up off the canister or tamp down any "gusts from below".

In practice over the last week, my impression is that the windscreen works very well, but that the "shield piece" below wasn't effective or necessary. The folded, flat edge at the top of the inverted cone kept the screen structurally stable in a crosswind and the stove cooked notably faster with the screen in place. It's also very light. However, the windscreen burned up, became ragged along its lower edges and it isn't durable enough to last many more boils and foldings to put back inside the kit. Also, to light the stove with the screen in place requires one to hold the mini-bic somewhat over the burner…and I now have less hair on the one hand than I did a week ago.

Back to the drawing board… Looking at the posts above, I am thinking of a tall, highly-vented, screen I could attach to the canister and have extend upward with an un-perforated section around the burner and HE fins. With large, side vents on the lower section, I could feed plenty of combustion air in and reduce a little weight, but I haven't figured out how to flare such a screen out to get around the pot (which is significantly wider than the gas cartridge that rides inside the pot when not in use) in a "lightweight manner". These are the things one ponders while waiting out a rainstorm.

[Mikael Akke]

Here's another real simple way of making an efficient windscreen. Make sure to monitor the temp of the canister.
http://outtherekids.wordpress.com/2012/08/15/on-windscreens-2

[Alex H]

Eirk it is a bit hard to visualize but sounds something like this one Ryan wrote about back in 2001
http://www.backpackinglight.com/cgi-bin/backpackinglight/00041

I use a Crux too and the way the pot supports are you can't make one like Ryans and have it hang on the pot supports and give room around the burner head, at least I couldn't.

Any pictures of yours?

I am using an 8" high Trail Designs Vari-Vent cut down both to diameter to allow about a half an inch around the pot and then with an inverted U opening to allow for more canister ventilation and to access the control knob. Has worked really well for 1.6 oz.

This is the only picture I have of it, doesn't show the opening though. If I get time I will take some shots of it.

[Author]

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