[HN Gopher] Testing the strength of different wood species
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Testing the strength of different wood species
Author : Ivoah
Score : 108 points
Date : 2021-12-17 17:23 UTC (1 days ago)
(HTM) web link (woodgears.ca)
(TXT) w3m dump (woodgears.ca)
| n-e-w wrote:
| I respect all wood
|
| https://youtu.be/NTL30rkRYPo
| wforfang wrote:
| For anyone who found this video satisfying, you may enjoy
| "Structures : Or Why Things Don't Fall Down" by Gordon.
| ggm wrote:
| This plus one thousand. Great book. "The new science of strong
| materials" is also good.
| dalke wrote:
| There's an interesting connection between this and edge-notched
| punched cards (a special interest of mine), via a 1936 article in
| Nature (See https://www.nature.com/articles/137535a0 .)
|
| Quoting Kilgour's "Origins of Coordinate Searching" at
| https://books.google.se/books?hl=sv&lr=&id=4crkFsx73msC&oi=f... .
|
| > In 1936, S. H. Clarke, of Britain's Forest Products Research
| Laboratory at Princes Risborough, published a brief note in
| Nature reporting on an unexpected observation: Detection of
| relations of ''recorded features'' on edge notched punched cards
| with a particular feature already sorted.
|
| > He had sorted a file of several hundred cards each listing a
| specimen of timber, by increases in specific gravity, and noticed
| ''by glancing at the arrangement of the other notches . . . a
| distinct tendency for strength to increase with specific
| gravity'' (Clarke, 1936, p. 535). He added that it was easy to
| recognize unusual correlations among notches.
|
| The spreadsheet plot in this video is essentially the same as the
| image in the 1936 Nature publication!
| Gravityloss wrote:
| For weight constrained beam applications, both bending and
| compression failures are bending related (tension isn't).
|
| Since bending strength is proportional to the cube of thickness
| of a beam, wouldn't less dense materials in practice always win
| out since you can make the beam thicker?
|
| Ie the characteristic metric for beams would be stiffness /
| density^3
| ggm wrote:
| That qualification of weight constraint. Brick pillars have
| sufficient compressive strength to hold fantastic weight, steel
| or stone as much if not more so (the structural rigidity of the
| bricks will largely depend on the mortar and skill of laying
| the courses) so I think this is a peculiar niche to be in.
| Church roofs use heavy trusses, the compression load is a big
| part of building strength in flying buttresses and arches.
| MatthiasWandel wrote:
| Typically the beam has to fit where it needs to go. A lighter
| beam doesn't mean you have room for a bigger one.
| zokier wrote:
| One thing that saddens me in the region I live is the lack of
| diversity in forests and therefore also in lumber selection.
| Quickly googling up some stats, 65% of forests are pine and 24%
| spruce. Only major hardwood would be birch (9% of forests), and
| its usually not available as lumber afaik.
|
| One of my dreams (in the category "if I were a billionaire")
| would be to buy some large piece of land and plant all sort of
| interesting trees to create a sort of fantasy forest.
| gotorazor wrote:
| Not true. I used to work at a lumber company. If you're in
| North America, you can usually buy some kind of hardwood. For
| utility lumber, they probably can't tell you what kind of
| hardwood it is, but it will be hardwood.
| zokier wrote:
| > If you're in North America, you can usually buy some kind
| of hardwood
|
| That's the thing, I'm not in NA, so pretty much any hardwoods
| available here are "exotic" imports.
| ilamont wrote:
| There's an episode of Grand Designs (season 10 or 11 IIRC) where
| the couple building the home chose Japanese larch for the
| cladding for their home in Wales. The specialist lumberyard used
| some sort of handheld tool to measure the density of the trees
| (harvested in Wales) and it was extremely strong ... but the show
| also noted the strength could vary widely from batch to batch,
| depending on variables such as age, soils, etc.
|
| Some details: http://www.cilfiegansawmill.com/forestry-wales/
| irrational wrote:
| I'm not surprised by Osage Orange. There is a reason it is prized
| by bow (as in archery) makers.
|
| Too bad they couldn't do Yew too. That is another top bow wood.
| silisili wrote:
| For anyone who doesn't know or look this up, Osage Oranges are
| what we in the Midwest called 'hedge apples', those creepy
| alien looking green balls you'd see littered in yards.
| tapvt wrote:
| Relevant article from Texas Monthly regarding the history of
| Osage Orange:
|
| https://www.texasmonthly.com/being-texan/osage-orange-histor...
| billti wrote:
| If you watch the linked video, six mins in he has a "bow score"
| based on strength and flex. Osage Orange was 2nd, after
| Dogwood.
| jimmyrocks wrote:
| After watching this, I made the connection that the French
| "Bois d'arc" for Osage Orange refers to its use in bows. It
| turns out that Osage Orange really is one of the best woods for
| bows.
| esotericsean wrote:
| So cool to see Matthias here on HN. He has a ton of other
| articles and videos where he tests different things like this. I
| encourage you guys to check him out if you haven't.
| slig wrote:
| Matthias is such an inspiration. A true hacker, I'd say.
| stcredzero wrote:
| I remember that he was recently trying to get hired at a tech
| company. (He was doing something like an Arduino auto-
| targeting Nerf gun as a portfolio piece.) Did someone nab
| him?
|
| I remember the days when YouTube videos were automatically
| flagged as "shallow" by the HN code!
| walrus01 wrote:
| I wonder how the "wood" 3D filament which is particles embedded
| in a brown PLA would compare. PLA is generally quite weak, this
| filament is only suitable for ornamental things.
|
| https://all3dp.com/2/wood-filament-for-a-3d-printer-explaine...
|
| For the actual woods, I am not suprised by the ironwood. I once
| had a coffee table with an ironwood top and it was ridiculously
| dense and strong.
|
| also, did you know there's an ironwood smuggling problem
| internationally?
|
| https://www.google.com/search?client=firefox-b-d&q=ironwood+...
| almog wrote:
| I would guess that much like MDF, PLA wood's strength is
| determined by the binding agent. My understanding of this
| product is that it's basically sawdust + PLA, whereas a wood's
| strength is stemmed (sorry!!) from its grain.
| l33tbro wrote:
| This is really fun - but isn't information about the janka of
| most species already fairly accessible online? [1].
|
| I always assumed there was a slight degree of strength variance
| due to age, humidity of growth region, etc - but maybe having
| your own tester might come in handy for certain structural
| engineering cases where accuracy is crucial.
|
| [1] https://www.wood-database.com/wood-articles/janka-hardness/
| thethirdone wrote:
| I haven't checked, but I would assume the janka hardness of
| wood is not super tightly correlated with yield strength. I
| would expect a variation of 2x for a the janka hardness :
| strength ratio; some wood would be twice as strong or half as
| strong as you might expect from the hardness.
| scns wrote:
| Without reading the article (gotta be honest), Ipe should rate
| highly if they test it. It is very dense. Heavier than water, it
| sinks.
| swayvil wrote:
| Hey I was thinking about ipe too. Bugproof, toxic dust and
| smoke. Heavy as heck. So hard you break bits, dull blades.
| Beautiful color and grain. Looks like walnut. Got a piece in my
| lap right now.
| lostlogin wrote:
| Australian hardwoods are a bit like this. Jarrah looks
| amazing, is crazy heavy and sinks. New Zealand power poles
| are still sometimes Jarrah.
|
| Another odd one is old olive. I've had sections that when hit
| with an axe won't split and bounce the axe. And seemingly
| remain unmarked. Splitting gnarled olive is miserable.
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