Doug Miller schreef
Yes, in general, density is an indicator for both hardness and strength, but a general trend is not a natural law. PvR
PVR notes:
Yes, density, strength and hardness are different things Yes, hard maple (there is only one species) is appr. 50% harder than soft maple (at least two species).
He does _not_ say that hardness is directly proportional to density, only that there is a relationship.
Yes, in general denser woods will be harder than lighter woods, but that does not mean that a wood that is twice as dense as another will automatically be twice as hard.
Yes, there are. Sort of. A. nigrum is often sold as "hard maple" and it is in fact a whole lot harder than silver maple (A. saccharinum), sold as "soft maple", but it's nowhere near as hard as A. saccharum, and isn't all that much harder than red maple (A. rubrum) which is also sold as "soft maple".
Specifics: (side hardness in lf-ft) saccharum 1450 nigrum 1180 rubrum 950 saccharinum 700
-- Regards, Doug Miller (alphageek at milmac dot com)
Nobody ever left footprints in the sands of time by sitting on his butt. And who wants to leave buttprints in the sands of time?
Sugar maple (Acer saccharum) is about 50% harder than red maple (A. rubrum), but it's *twice* as hard as silver maple (A. saccharinum).
Black maple (A. nigrum) is also sold commercially as "hard maple". Its hardness is almost exactly midway between rubrum and saccharum.
-- Regards, Doug Miller (alphageek at milmac dot com)
Nobody ever left footprints in the sands of time by sitting on his butt. And who wants to leave buttprints in the sands of time?
(with minor editing by FF)
Also:
(Bigleaf) macrophyllum 833 (Boxelder) negundo 720
There are other species like striped maple (pennsylvaticum) but those above are about all the commercial species found in the US.
I have a guitar with a hard maple body. It has tremendous "punch" to the sound, easily louder than most guitars, with a very bright, clear tone. Wish I could find the time to learn to really play it.
-- "We need to make a sacrifice to the gods, find me a young virgin... oh, and bring something to kill"
Tim Douglass
in fact a whole lot harder than silver maple (A. saccharinum), sold as "soft maple", but it's nowhere near as hard as A. saccharum, and isn't all that much harder than red maple (A. rubrum) which is also sold as "soft maple".
*** Yes, "sort of" is rather precise. Black maple is a maple that drifts into and out of /Acer saccharum/, as either a subspecies or variety. If you go and look for them, you will find supporters for all three positions (/Acer nigrum/, /Acer saccharum/ subsp /nigrum/ and /Acer saccharum/ var /nigrum/). I called it one species to 1) make the point that they are not entirely separate maples and 2) the latest big monograph to deal with all the maples of the world (i.e. "Maples of the World", 1994) regards the Black Maple as a subspecies. So, it is on good authority.And yes, the four biggest units (sugar, black, silver and red maple) are listed as being of different hardness, so it depends on the way you calculate how close the "appr. 50% harder" is true. Close enough, I'd say? The figures given are all averages anyway, not absolute figures that are very likely to exactly fit the wood one will have at hand (not to mention that hardness of any given piece of wood will vary with moisture content), so anything one would care to say is only approximately ...
Yes, "sort of", indeed. PvR
Oops, typo, sorry. Meant to type "lb-ft". Thought I had. Thanks.
My source shows 850, FWIW.
-- Regards, Doug Miller (alphageek at milmac dot com)
Nobody ever left footprints in the sands of time by sitting on his butt. And who wants to leave buttprints in the sands of time?
But "lb-ft" are the wrong units. Pound-feet or foot-pounds, are units of energy or moment or vice versa, there is a convention for the ordering of the factors, evidently preferred by professors of engineering who are weak on the concept of the communitive property of multiplication. Sometimes you will also see lbf-ft or ft-lbf. In civil engineering "Geodesics" may be defined as lines of constant energy. I _think_ that means that the moment supported by a structure along those lines is constant, implying constant potential energy. R. Buckminster Fuller could no doubt have explained it far better.
IMHO "lbf" is silly anyhow as "lb" should be understood to be force unless otherwise specified since pounds-mass is an obnoxious unit, slugs are far easier to work with when you need to use honest-to-god ACU mass units.
(Watch out, a linguist might pop up any minute and start a discussion of how words used to refer to mass and weight have evolved over the millenia. It is actually quite interesting.)
I found some that say that too. Few sources give any sort of range but I expect that there is considerable natural variation in the material properties of wood, +/- 10% for most species would not surprise me.
Mutt schreef in
*** No, on average it is over twice as hard. If you really look, you can likely find pieces that show a difference of three times.*** So that he can explain again what the past fifty years of explaining has failed to get across? I don't know Hoadley's temper but probably he will regret having written the book, as the readers don't understand what it says? PvR
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