Archive for 2014

Titanium Grades (for your ultralight projects)

Wednesday, October 8th, 2014

Ok, ok, I know, you are saying, who cares? But I was curious about titanium wire grades (for my ultralight titanium pot stands) so I found this chart here.

Element Composition,%
Grade1 Grade2 Grade3 Grade4 Grade5 Grade6 Grade7 Grade9 Grade11 Grade12
N max 0.03 0.03 0.05 0.05 0.05 0.03 0.03 0.03 0.03 0.03
C max 0.08 0.08 0.08 0.08 0.08 0.08 0.08 0.08 0.08 0.08
H max 0.05 0.015 0.015 0.015 0.015 0.015 0.015 0.015 0.015 0.015
Fe max 0.2 0.3 0.3 0.5 0.4 0.3 0.5 0.25 0.2 0.3
O max 0.18 0.25 0.35 0.4 0.2 0.2 0.25 0.15 0.18 0.25
Al 5.5-6.75 4.0-4.6 2.5-3.5
V 3.5-4.5 2.0-3.0

Note that lower grades are really soft, so I wanted to know what grade 5 is. Now I know.

Further, from wikipedia we learn:

Grade 1 is the most ductile and softest titanium alloy. It is a good solution for cold forming and corrosive environments. ASME SB-265 provides the standards for grade 1 titanium sheet and plate.[4]

Grade 2 Unalloyed titanium, standard oxygen.

Grade 2H Unalloyed titanium (Grade 2 with 58 ksi minimum UTS).

Grade 3 Unalloyed titanium, medium oxygen.

Grades 1-4 are unalloyed and considered commercially pure or “CP”. Generally the tensile and yield strength goes up with grade number for these “pure” grades. The difference in their physical properties is primarily due to the quantity of interstitial elements. They are used for corrosion resistance applications where cost, ease of fabrication, and welding are important.
Grade 5, also known as Ti6Al4V, Ti-6Al-4V or Ti 6-4, is the most commonly used alloy. It has a chemical composition of 6% aluminium, 4% vanadium, 0.25% (maximum) iron, 0.2% (maximum) oxygen, and the remainder titanium.[5] It is significantly stronger than commercially pure titanium while having the same stiffness and thermal properties (excluding thermal conductivity, which is about 60% lower in Grade 5 Ti than in CP Ti).[6] Among its many advantages, it is heat treatable. This grade is an excellent combination of strength, corrosion resistance, weld and fabricability.

“This alpha-beta alloy is the workhorse alloy of the titanium industry. The alloy is fully heat treatable in section sizes up to 15mm and is used up to approximately 400°C (750°F). Since it is the most commonly used alloy – over 70% of all alloy grades melted are a sub-grade of Ti6Al4V, its uses span many aerospace airframe and engine component uses and also major non-aerospace applications in the marine, offshore and power generation industries in particular.”[7]

“Applications: Blades, discs, rings, airframes, fasteners, components. Vessels, cases, hubs, forgings. Biomedical implants.”[5]

Now I know, that’s why people use Grade 5, and that’s what I am looking for. Specifically, 0.08″/2mm titanium wire. They call it wire rather than rod when it’s thinner than about 0.125″ I believe, give or take. Anyway, for stuff of about 2mm it’s wire, no matter what the cutoff point.

Note: it’s really hard to find grade 5 2mm titanium online, but you can find it if you google for titanium bike spokes, they run about $2 each, make sure to get longer ones, most are for bmx bikes, and are too short for things like pot stands etc. 14 gauge spokes are 2mm which is about 0.08″. Spokes will be made out of very strong alloys.

Protecting silnylon against misting in heavy driven rains

Tuesday, August 19th, 2014

I came across this very good explanation of how to add a bit more silicone to your silnylon tent/tarp to protect against heavy driven rain, which causes inner misting. I was not completely sure that this actually happens, until my last trip, where it clearly happened. All doubt was removed in my case because I had pitched the tent on a dry spot, relatively, thunder was booming in the distance, then it started to rain, then almost immediately, a heavy hail (3/8 inch or so), I got in my tent, zero time for condensation to form, and the misting started instantly, it’s very clear and defined, nothing to do with condensation, so if you read people trying to pretend this phenomena is just inner condensation getting knocked off by the outer rain, they don’t know what they are talking about, but probably think they do.

In an unrelated heavy rain in Norway discussion thread Eric Blumensaadt gave this excellent short summary on how to treat your silnylon to fix the misting problem, I’ve read several, and this one seems to be about perfect, thanks.

Re-coat the silnylon tent with a 5:1 ratio by volume of 5 parts of odorless mineral spirits to 1 part clear GE Silicone II (or European equivalent). Place in a suitably sized jar with a tight lid. Shake well to mix and shake every 5 minutes while using.

Apply in sections with a very short nap, narrow paint roller – pour small amounts in a roller pan. You can also use a fine bristle brush. Spreading the tent sections on a smooth top table is far better than using the floor.

BE SURE to wipe the excess off each section immediately with a heavy duty paper towel (“shop towel”). Rolling on the mix is faster and gives a more even coat than brushing. Wiping immediately after leaves only the necessary amount on the silnylon, thus reducing weight AND GREATLY REDUCES DRYING TIME by days. Silnylon floors or ground cloths (“footprints”) can be coated twice using this method for a heavier coating.

BTW, this procedure will seal the tent exterior seams but I would recommend also coating the interior seams as well. If seams ever leak after this treatment (doubtful) use a 3:1 ratio of mineral spirits to clear silicone caulk for re-sealing. Do NOT wipe this seam seal treatment. Just let it dry in the hot sun. The Netherlands does have hot days, right? My experience with Dutch weather was in late October when it was cold and rainy.

I didn’t want this little gem to just vanish in the never ending churn of gear talk etc on, so I am saving it here so it doesn’t get lost.

Technically, I believe you can use Coleman white gas type fuel instead of the mineral spirits, and I believe silicone cures better in humid climate, though I’m not positive about that. Also of course, it’s hard to use rollers if you don’t have a big work space.