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[Uristocrat]

They're definitely not a major construction material, but some of the local natives did use poles made out of saguaro rib to harvest the cactus fruit from the top of other saguaros.  I think I've also seen it used to make fences.

The wood is reported to be very light and very strong.  The downside is that it's a bunch of long, not-too-thick poles arranged in a ring (this is why they're called "ribs").  This actually helps it withstand wind (and I ended up reading a research paper to that effect in a vain attempt at finding the wood's density) as people have proved by putting models in wind tunnels.

That said, it *can* be used to build things, it's just not easy or particularly economical.  I guess it's pretty trendy, though, among those who like southwest-style stuff.  After all, the guy helping me makes random bits of artwork out of them.  And there's a newspaper article from long ago about someone who made clocks out of mesquite and saguaro wood.  Yes, I read a *lot* of random stuff about saguaros when trying to look up a simple density value....

[Uristocrat]

I now have Saguaro wood!  Rick was very, very generous and supplied me with more Saguaro wood than I know what to do with.

The hard part now is experiment design to measure the material properties.  I have a few ideas of my own, but suggestions are always welcome.  I have a few dozen foot-long pieces of rib as well as a few other odds and ends.  I'm also open to the idea of shipping some of it out to anyone else who wants to do experiments.  My first estimate will use the cubes for me, which are roughly one cubic inch.  My micrometer is at work, and they're not 100% square, though they're awfully close, but can still measure them reasonably well with a ruler.

The better one has a mass of 6 grams (the scale only has an accuracy of +/- 1 gram, sorry).  The measurements I get on each face are:

A:  2.49 - 2.43 cm
B:  2.30 - 2.29 cm
C:  2.45 - 2.50 cm

Those ranges are the width of that dimension at the top and bottom.  Like I said, it's not quite square, though this cube has fairly sharp edges.  That gives us a volume of about 14 cm^3.  Converting that to Dwarf Fortress terms means that Saguaro wood has a density of approximately 430 kg/m^3.  There's a fair amount of uncertainty in that number, however.

This seems like a reasonable number based on my other research.  I had a guesstimate of 300 in the V2 raws, but it wouldn't surprise me to learn that it was too low.

If anyone has suggestions for how to test other material properties, I'm all ears.  And I have a *lot* of bits of Saguaro wood for anyone who wants to do experiments on it.

[Rose]

probably a better way to test the volume would be to jab a long and thin needle into the end, and dunk it into a measuring cup. One that you know is accurate.

[Uristocrat]

probably a better way to test the volume would be to jab a long and thin needle into the end, and dunk it into a measuring cup. One that you know is accurate.

I don't have any good glassware for that, unfortunately.  I'm not opposed to shipping samples to anyone who wants to do their own tests, though, especially if someone does have better equipment or they can test other material properties.

I have more little rib pieces than I know what to do with.  Also, I fear that the accuracy of my scale is really the limiting factor here.  It only goes to the nearest gram   I mostly use it to weigh stuff like flour for cooking, so....

[Rose]

You could try visiting your local high school and ask if you could use their labs. they might oblige.

[Uristocrat]

You could try visiting your local high school and ask if you could use their labs. they might oblige.

I honestly don't know where any of the local high schools are, nor do I know anyone there, because I didn't grow up in this city.

[Spitfire]

You could try visiting your local high school and ask if you could use their labs. they might oblige.

I honestly don't know where any of the local high schools are, nor do I know anyone there, because I didn't grow up in this city.

Oh come on do it! =D Good teachers are glad about everyone who wants to !!SCIENCE!!, ehm no actually they only value science, no matter if they are related to the school or not.

[Uristocrat]

You could try visiting your local high school and ask if you could use their labs. they might oblige.

I honestly don't know where any of the local high schools are, nor do I know anyone there, because I didn't grow up in this city.

Oh come on do it! =D Good teachers are glad about everyone who wants to !!SCIENCE!!, ehm no actually they only value science, no matter if they are related to the school or not.

Well, if I could go back to my old chemistry teacher, we used to have a lot of fun.  Some of it actually was !!SCIENCE!! ... though we were careful to make sure no one got hurt.

[Uristocrat]

I was asking Dr. Luuvalo whether density values for metal alloys could be calculated with a weighted average (e.g. if you have an alloy of 70% X and 30% Y, then (0.7*density_X) + (0.3*density_Y) would be a good approximation of the alloy's density) when he replied with this PM.  I'm reproducing it here because I think it will be helpful to anyone else trying to understand the material system and calculate material values.

Yes, that is how I would calculate density for alloys. It probably produces sufficiently accurate values for the game's scope.

Raw values for yield and fracture apparently represent yield strength and ultimate strength (UTS, UCS etc.) in kPa for respective load types. Values for torsion, shear and bending are somewhat redundant, as you can get proper result by using compressive and tensile strengths alone, and Toady has simply used tensile for these. I have no idea what the values for impact mean. Perhaps I should ask Toady about them, though I hesitate to bother him.

The something_STRAIN_AT_YIELD tells us how much the material deforms before yielding, for example iron deforms 0.073% in under tensile load before yielding. It is simply the yield strength in question divided by respective elastic modulus in GPa (Young's for tension, bulk for compression and shear for shear), and then again divided by 10.

I'd guess the MAX_EDGE is just some abstract value used to represent the fact that metals make better blades than say wood.

[Uristocrat]

I finally got around to uploading the V3 RAWs.  They're just a couple of minor corrections based on improved research, but it's better than leaving people to download the old numbers.  Maybe one of these days, I'll figure out what to do with my box of Saguaro wood....

[NTJedi]

Impressive... (according to the most recent update this will be in the next version)... Most Impressive

[Jon-Ace]

Congrats on the inclusion in DF!

[Taffer]

Good job. Exciting stuff, I'm looking forward to the update.

[Reudh]

I don't know whether anyone has mentioned monoclinic sulphur since you mentioned it; but as an allotrope of sulfur that only exists above 95.6 C / 368 K it would be more or less useless unless we can make rocks shift between allotropes at certain temperatures.

[Uristocrat]

I don't know whether anyone has mentioned monoclinic sulphur since you mentioned it; but as an allotrope of sulfur that only exists above 95.6 C / 368 K it would be more or less useless unless we can make rocks shift between allotropes at certain temperatures.

I don't remember if it came up or not, but I didn't use its density value, anyhow.  DF's simulation isn't quite that crazy, though there are liquid densities for some things that I never really looked up.  Actually, I did find that some of the template values were a little bit off (e.g. soil should likely be ~1600-1700, if I compare it to the average soil), but those all get overridden in the raws, so I don't think it makes any real difference.

Anyhow, I would like to thank Toady for including this research!  I'm glad it proved useful.

Nobody else has probably noticed, but we now rank as the #1 Google result for "Saguaro wood density" and this appears to be the only place on the entire internet that contains that data.  And yes, that is how I refer back to this thread