7075-T6 Alum vs. Titanium Stakes

So to be clear the aluminum stake is Thicker, Lighter, Stonger and Cheaper then the titanium stake.

If this is true I can't see why anyone would perfer the titanium stake other than that it is titanium. I would definately perfer the aluminum version perferably anodized a fun color.

I suspect it is like the Titanium pots people buy. It is really hard to beat the Stanco Grease Pot with any titanium pot of similar size but people still spend $50 on a ti-pot.

+1 on the aluminum. All my cookware is aluminum or lexan. All my stakes are aluminum. Only my stove is titanium-a Snowpeak gigipower. I've never understo0d the Ti mania except in relation to heat on very thin material .

>> If this is true I can't see why anyone would perfer the titanium steak

My dentist would kill me. ;)

>>>"So to be clear the aluminum stake is Thicker, Lighter, Stonger and Cheaper then the titanium stake."<<<

YES :)

Maybe they want to use them in winter since Ti won't freeze in the ground like Al? I'd prefer the stronger, lighter and cheaper Al. What weight are you expecting for them?

Titanium sounds much cooler, the common perception is that it's stronger for the same weight.

Ryan

Hi Lawson

A good question indeed. I have two answers for you.

The first is as OP mentioned, in frozen ground the aluminium stakes can be the very devil to extract, while Ti ones will come out with not too much effort.

The second is one which also bugs me with the common Y stakes. The larger cross-section makes it MUCH harder to get the stake into the ground. That's the really great thing about the thin Ti wires: they go into very hard soil quite easily, while holding very well. The larger or thicker stakes wreck the palm of my hand when I try to push them in. Yes, the 0.156" Al is only 55% bigger in cross-section, but I don't think the increase in push-force is linear. Thin wires go in much more easily: displacing the soil is non-linear.

OK, my particular hang-up. But I do have this callus on the palm of my right hand …

On a more practical note: putting a hook into 7075-T6 Al alloy may actually be difficult, and may weaken or crack the aluminium. You might like to check how much damage is done to the aluminium first.

Cheers

Lawson,

Do you have some backup data for your calculations?
I just ran a quick and dirty on these two materials, using a simple cantilevered round beam approximation, and my numbers aren't really jiving with what you've presented.

Assuming equal lengths, equal force being applied, and the given diameters, at a given force the aluminum stake at its region of max stress is something like 13% nearer to its yield stress point. Also, the Aluminum, as far as I can tell, would be only something like 1.2% lighter than the Ti, almost negligible at that length.

This all assuming I'm doing my calculations right, I am admittedly NOT a structural engineer (mechanical actually) and am a number of years removed from my last solid mechanics class, so it is equally likely (more?) my numbers are off. I'd be interested to see how you made your calculations.

Regardless of the calcs though, I think if there were stakes that seem by the numbers to be, at worst, of similar strength for half the price, there would be a market for them.

"On a more practical note: putting a hook into 7075-T6 Al alloy may actually be difficult, and may weaken or crack the aluminium. You might like to check how much damage is done to the aluminium first."

Roger makes a very good point that I hadn't considered. Aluminum is VERY picky about bend radius, cracking is frequently a problem, and fatigue is always a factor. Additionally, its much lower hardness could be very detrimental when faced with the abrasion/gouging that stakes face going into rocky ground.

At the end of the day, you now have an excuse to tinker, and then go camping…sounds like a truly unfortunate situation!

I think the formula goes something like yield x diameter x diameter x diameter / yield x diameter x diameter x diameter.

7075-T6 has a yield of 83KSI and the stakes have a diameter of .156"
6AL-4V has a yield of 128KSI and the stakes have a diameter of .125"

So it would be 83 x .156 x .156 x.156 / 128 x .125 x .125 x .125 = 1.26 which would equal 26% more bending resistance for something that weights 7% lighter.

You're not taking into account the moduli of the materials, which really makes a large difference in a calculation such as this, if I'm thinking about it correctly.

Unfortunately my mechanics book is sitting in my desk drawer at work, or I'd dig into this more deeply. Guess it will have to wait til next week (hiking all weekend!).

At the end of the day though, just make a few and test them. Beat them up and see if they're up to snuff. If so, sell 'em!

"I've never understo0d the Ti mania except in relation to heat on very thin material ."

cause you save that extra few grams … and itll make all the difference in the world in yr trip !!!

well really cause it sounds so cool to say ive got "titanium" ;)

i usually just use aluminum …

I'm far from knowledgeable in this area, but one of the things I like about titanium is that it's a wee bit springy. So if you're pushing a stake into the ground and it's not going, you can see it start to bend and then you can ease off before a permanent bend is created. I'm not sure how aluminum is, but this characteristic of Ti saves me a lot of bent stakes and enables me to push/hammer them in right at the limit of their strength without exceeding it.

The Ti stakes that I got from you Lawson have been awesome in this regard. I spent a few days camping in campgrounds with rock hard packed gravel campsites and the slight springy-ness of the ti enabled me to push them in as hard as possible without exceeding their limits. With some stakes I've used (not sure of the material) you don't know the limit, so all of a sudden you've got a nicely bent stake. From what I've heard, aluminum has more of a tendancy to crack than ti and it's not springy, but there are all sorts of variations on these metals so I can't speak to 7075-T6 Aluminum specifically.

7075-T6 is not to be bent, you will have failures at some point in the bend. Other aluminum allows are sometimes formed in the raw, and then heat treated, but this does not go for 7075, its structual, so typically no forming, and no welding.

Anodizing will help greatly with winter removal.

Roger, Use your feet ;-)

Don't get me wrong, I really like titanium tent stakes and I sell alot of them but if there is a better, stronger, cheaper alternative then I am game. I asked a engineer friend to do some calculations for me and these are the numbers he came up with. My friend mentioned Modulus too, but said that since the load/force was parallel to the rod that it really doesn't come into play but I am sure he could be wrong. I think real world performance is the ticket. Look at carbon fiber. On paper it would make a seriously awesome tent stake until you drive it in hard soil and it shatters..

As far as bending 7075 T-6 aluminum. It bends in my bender just fine..

why not make the 7075 like those MSR's one?
no bend require !

I actually thought about buying the material by the sheet and having the hook shape cut on a water jet. The square shape would be kind of cool.

Note: I just saw REI sells a 7075 T-6 Hook. Anyone use those before?

I think water jet would be a good way to do it.

Lawson,

The bigger question I'm wrestling with is whether or not the stakes you are contemplating will sell, regardless of how they compare to ti stakes.

Persnally, I'm satisfied with the stake choices that are currently available. To wet my appetite for a new stake would take some educating/selling.

Daryl

Problem with water jet being material usage, with an oddly shaped object like a shepherd's hook stake, you'd have a difficult time nesting a bunch of these together closely, unless you change the geometry of the stake. Even with good nesting, you'd lose a fair bit of material, which (material cost) was one of your primary "pros" listed for this.

very true.

"You're not taking into account the moduli of the materials, which really makes a large difference in a calculation such as this, if I'm thinking about it correctly."

titanium has a higher modulus than aluminum, so given the same size beam, an aluminum one will bend more than a titanium one under the same load

however, aluminum is lighter than titanium. so, in theory your beam can be made of thicker aluminum. this added thickness will make it bend less under the load and it will be on par with the titanium beam from the first example.

so you have a modulus vs. density comparison for some given beam shape. funny enough, steel, titanium, aluminum, and magnesium are all kind of equal to one another in that comparison.

the trick to the above scenario comes down to volume. a magnesium beam that supports a given weight while only bending a certain amount is significantly larger than a steel beam that weighs the same and bends the same under the load.

here is where carbon fiber is a winner. it has a high modulus and a low density compared to those metals.

of course we are talking about tent stakes here where modulus isn't really important due to the application. the stakes are being axially loaded when driven in. strength of the material will be more critical. strength can be increased for a given material by certain treatments and alloys. 7075 is very strong aluminum. still bends as easily as the other aluminums out there but it takes more force to deform it permanently. titanium is even stronger than that. titanium is harder too so given the same shape the titanium will hold it's point better.

but here come the old weight thing again. more aluminum could be used to change the shape to make it more resistive to deforming

now I'm just babbling on… but usually innmy line of work it comes down to more than just a couple parameters to determine the optimal material for a given application

one thing that titanium has over other materials is that it is very resistive to corrosion and it maintains it's strength better at higher temperatures. neither of these usually comes into play in the backpacking community soni kind of think of it as a gimmicky marketing material in most outdoor sport applications

Lawson

I'm not saying you cant bend it, I'm saying without doing it properly(raw-to-aged), it will fail at the bend at some point. The initial bend will create a "craze" mark/s on/just below the surface. The craze mark will grow with each load cycle, with the craze growing into cresent moon shaped "beach marks", that slowly penetrate into the shaft until it breaks. The break will be spiral/semi spiral, or beach mark through the shaft 90 to the axis, this is text book. Aerospace gear and control boxes utilize allot of 7000 series aluminum because of its strength. While bicycle frames for example tend to be 6000 series or other aluminum alloys because they handle load cycling better than 7000 series aluminum. I have built quite a few of both. The stakes could have some potential, but like was mentioned earlier, go with a nail type head, or go with a reduced diameter, just below the drive end, with a cord attachment.

> Look at carbon fiber. On paper it would make a seriously awesome tent stake until you drive it in hard soil and it shatters.

They apparently don’t shatter

Dustin Snyder was also making these but he’s removed all his posts until later – perhaps so people don’t take his ideas?